# Glossary of Terms

#### Click here to return to the title

###

> Select the first letter of the word from the list above to jump to appropriate section of the glossary.

> ## - A -

> Back to Top
> AAL
> ATM Adaptation Layer: Provides for reliable segmentation and reassembly of user traffic into 48 octet payloads.
> ABR
> Available Bit Rate: A quality of service designed to support data, including a flow control mechanism to support congestion problems in the network.
> access control
> Software, hardware, and administrative policies and procedures that monitor host or network operation, identify users, verify security codes or password(s), and record access.
> Access Control List (ACL)
> The list of the services available on a network or host and users permitted to use each service. This is the usual way that access to services (or denial of access) is controlled in most networks and multi-user host security systems.
> ack
> See Acknowledgment.
> acknowledgment (ack)
> A type of message sent to show that another previous message arrived at its destination without error.
> ACL
> Acronym for Access Control List.
> active hub
> A device used to amplify transmission signals in certain network topologies. An active hub can be used to either add additional workstations to a network or to lengthen the cable distance between nodes, workstations, and/or file servers on a network.
> active monitor
> Token ring software that removes data packets that have not been picked up from the ring by its target station.
> active star
> A hub-based networking topology that regenerates signals in active hubs.
> activity daemon
> A process that keeps a list of active agent requests sent from the host (where the daemon is running). The daemon periodically queries the agents to make sure they are still servicing their requests.
> AD
> Acronym for Administrative Domain.
> address
> An identified name for a logical or physical item that can be used to connect to that item.
> address mask
> A bit mask used to identify which bits in an address (usually an IP address) are network significant, subnet significant, and host significant portions of the complete address. This mask is also known as the subnet mask because the subnetwork portion of the address can be determined by comparing the binary version of the mask to an IP address in that subnet. The mask will hold the same number of bits as the protocol address it references.
> address resolution
> A means for mapping logical addresses to media-specific physical addresses when both pertain to the same device. See also: ARP.
> Address Resolution Protocol (ARP)
> A protocol used to dynamically discover the low level physical network hardware address that corresponds to the higher level protocol address for a given host. ARP is limited to physical network systems that support broadcast packets that can be heard by all hosts on the network.
> address space
> A collection of addresses that form a unified collection (such as an internetwork) or the portion of a protocol header that contains an address.
> address translation
> The process of converting an external address into a useable standardized internal address and vice versa.
> addressing authority
> The group responsible for assigning addresses within a domain.
> Administrative Domain (AD)
> A group of hosts, routers, gateways and interconnecting networks, if more than one, managed by a single organization or administrative authority. Routing within an administrative domain is based on a consistent plan.
> agent
> (1) A network management term for the portion of an entity that responds to management requests and/or preprogrammed traps. (2) In the client-server model, the part of the system that prepares information and exchanges it for a client or server application.
> Aggregated Purchasing
> Online purchasing that aggregates demand and provides discounts through group buying power.
> Agility Factor
> Refers to a phenomenon known as "Internet time" where one month of elapsed time is equal to an entire year in the bricks-and-mortar world.
> alias
> A name, usually easy to remember, that is translated into (or is a translation of) another name that is usually difficult to remember.
> allocation
> A concept used in the transport layer protocols. It is the amount of traffic that may be outstanding, without acknowledgments, at one time; also called window, as in sliding window.
> alternate route
> A secondary communications path used to reach a destination if the primary path is unavailable.
> alternate routing
> A way of completing connections that uses another path when the previous circuit is unavailable, busy, or out of service.
> alternate use
> The ability to switch communications facilities from one type to another, i.e., voice to data, etc.
> AME
> ATM Management Entity
> American National Standards Institute (ANSI)
> A private organization that coordinates some U.S. standards setting. It also approves some U.S. standards that are often called ANSI standards. ANSI represents the United States to the International Standards Organization (ISO). See also: International Standards Organization.
> American Standard Code for Information Interchange (ASCII)
> A standard character set that typically assigns an 7-bit sequence to each letter, number, and selected control character. It is erroneously used now to refer to 8-bit, extended ASCII. The other major encoding standard is EBCDIC.
> anonymous FTP
> Anonymous File Transfer Protocol lets users retrieve documents, files, programs, and other data from other TCP/IP connected hosts without having to establish a user ID and password. The special user ID of "anonymous" and password of "guest" or the user's E-mail address lets that user bypass local security checks and have access to selected files on the remote host. See also: File Transfer Protocol.
> ANSI
> Acronym for American National Standards Institute.
> Apple
> Maker of AppleTalk and the Macintosh.
> AppleShare
> Program that lets different types of computers offer or use AppleTalk resources, like printing.
> Applet
> A computer program designed to be executed from within another application.
> application
> A program that performs a user function; synonymous with program.
> application environment specification
> A goal of the Open Software Foundation.
> application layer
> The top-most layer (Layer 7) in the OSI Reference Model providing such communication services as electronic mail and file transfer. It is generically defined as the top layer of a network protocol stack.
> application process
> A part of a distributed application running on a single host; synonymous with process.
> application terminal
> An object accessed by an application on a slave node. For example, a printer attached to a terminal server would be the application terminal for the print spooler.
> architecture
> The relationship of the physical parts of a computer or network that is typically labeled by that relationship. For example, the Motorola 68000 architecture.
> area
> A term used, particularly in OSPF, in the routing layer to describe a group of networked devices; it is similar to a subnet.
> ARP
> Acronym for Address Resolution Protocol. Address Resolution Protocol is used to determine an IP host?s layer 2 MAC address.
> ARPA
> Acronym for Advanced Research Projects Agency.
> ARPANET
> Acronym for Advanced Research Projects Agency Network.
> AS
> Acronym for Autonomous System.
> ASCII
> Acronym for American Standard Code for Information Interchange.
> ASCII terminal
> A terminal that uses ASCII. The name frequently given to asynchronous terminals; synonymous with dumb terminal or glass tube.
> ASIC
> Application Specific Integrated Circuit. A chip that is custom designed for a particular application.
> assigned numbers
> The codes (numbers in hexadecimal, decimal, and/or binary format) that are officially recognized and assigned as part of the Internet standards.
> Assigned Numbers RFC
> The RFC that documents the current values for several series of numbers used in network protocols. This RFC is updated periodically. Current information can be obtained from the Internet Assigned Numbers Authority (IANA).
> asymmetric modem
> A full duplex modem that simultaneously sends data at two different speeds; for example, data is transmitted at high speed and acknowledgments are received at low speeds.
> async
> Asynchronous; a data transmission method that sends one character at a time. Contrast with the synchronous methods, which send a packet of data and then resynchronize their clocks. Asynchronous also refers to commands, such as in a windowing environment, that may be sent without waiting for a response from the previous command.
> asynchronous communication
> Communication in which the spaces between bytes or packets can be unequal lengths without needing timing data or synchronization. Sometimes called asynchronous transmission:
> asynchronous communications adapter
> A hardware device or module that lets a host system use an asynchronous data stream to send data to a desired target.
> asynchronous event
> Events that occur asynchronously on a system so that the user cannot predict which one will happen next.
> asynchronous gateway
> A device that lets asynchronous devices attach directly to a network; the generic term for a terminal server.
> asynchronous mode
> An OSI model for virtual terminal operation in which either side may communicate at any time.
> asynchronous modem
> A modem that uses async for transmitting data. Such a modem does not require synchronization with the remote modem or with the attached device.
> Asynchronous Transfer Mode (ATM)
> A method for the dynamic allocation of bandwidth using a fixed-size packet (called a cell). ATM is also known as "fast packet" and is an emerging WAN and LAN standard.
> ATM
> Acronym for Asynchronous Transfer Mode.
> auth
> Authentication Service.
> authenticate
> The function of verifying the identity of a person or process.
> authentication
> (1) The verification of the identity of a person or process. (2) The code used to identity a person or process.

> ## - B -

> Back to Top
> b
> Bit
> B
> Byte
> B channel
> Bearer channel. A basic component of ISDN interfaces. It can carry voice or data at 64 Kbps.
> backbone
> The main connectivity device of a distributed system. All systems that have connectivity to the backbone will connect to each other. This does not stop systems from setting up private arrangements with each other to bypass the backbone for reasons of cost, performance, or security.
> backbone cable
> A main cable run vertically (or horizontally) in a building to provide wire connectivity to separate areas in the building. It is not designed for direct system access.
> backbone closet
> Space provided in a building for terminating pairs of wire and for connecting the backbone cable to systems in that area.
> bandwidth
> Technically, the difference, in Hertz (Hz), between the highest and lowest frequencies of a transmission channel. Usually identifies the capacity or the amount of data that can be sent through a given circuit.
> bang
> A UNIX term for the exclamation point (!).
> Bank Rate
> A percentage of each sale that the bank charges for processing credit card transactions. Also known as a ?discount rate.?
> banner
> A screen or page of printout (usually at the beginning) that gives information about the network, server, or file being accessed or printed.
> base memory
> The beginning of a block of memory. A network interface board uses the base memory address as a buffer. This is the address where both the computer and the network interface board can leave information and signal the other to pick it up.
> Basic Input/Output System (BIOS)
> A set of programs, usually in firmware, that lets each computer's central processing unit communicate with printers, disks, keyboards, consoles, and other attached input and output devices.
> Basic rate interface (BRI)
> One of the two forms of ISDN. It offers 144 Kbps service that includes two 64 Kbps channels (for data, voice, or video) and one 16 Kbps channel for control information.
> baud
> A unit of signaling speed. The speed in baud is the number of discrete conditions or signal elements per second. If each signal event represents only one bit condition, then baud is the same as bits per second. Baud rarely equals bits per second.
> baud rate
> The rate at which data is transferred over an asynchronous RS-232 serial connection.
> BDC
> NT Backup Domain Controller
> beacon
> A token ring packet that signals a serious failure on the ring.
> benchmark
> A point of reference from which measurements can be made. It involves the use of typical problems for comparing performance, and is often used in determining which computer can best serve a particular application.
> BGP4
> Border Gateway Protocol Version 4 (BGP4) is a protocol that includes authenticated routing updates, CIDR, and supernetting which reduce the size of routing tables and introduce other internet addressing and routing efficiencies.
> binary
> Base 2. Also known as "bin". Decimal, or base 10 is the common numbering system used by people in everyday life. Computers internally use base 2 (binary), base 8 (octal) or base 16 (hexadecimal) and only convert numbers to base 10 for human consumption.
> - decimal 2 = 10 binary
> - decimal 4 = 100 binary
> - decimal 5 = 101 binary
> - decimal 6 = 110 binary
> - decimal 10 = 1010 binary
>   BIOS
>   Acronym for Basic Input/Output System.
>   bit
>   A binary digit; must be either a 0 or a 1. It is the smallest unit of information possible, and indicates one of the two electrical states: off (O) or on (1) in a computer.
>   bit bucket
>   An imaginary place where bits are thrown away as if it were the bit wastebasket.
>   bit rate
>   See bits per second.
>   bits per second (bps)
>   Basic unit of measurement for serial data transmission capacity, abbreviated as k bps, or kilobit/s, for thousands of bits per second; m bps, or megabit/s, for millions of bits per second; g bits, or gigabit/s for billions of bits per second; t bps, or terabit/s, for trillions of bits per second.
>   boot
>   Short version of "bootstrap". To load a computer's memory with the necessary information so that it can function.
>   boot up
>   See boot.
>   BOOTP
>   Acronym for the BOOTstrap Protocol. It is used for booting diskless nodes.
>   Border Gateway Protocol (BGP)
>   A suggested routing protocol for autonomous systems. It is based on lessons learned while using EGP.
>   BRI
>   Acronym for Basic Rate Interface.
>   Bricks-and-Mortar Business
>   Refers to a traditional storefront enterprise.
>   bridge
>   A device that expands a Local Area Network by forwarding frames between data link layers associated with two separate cables, usually carrying a common protocol. Bridges can usually be made to filter packets (to forward only certain traffic). In OSI terminology, a bridge is a Data Link Layer intermediate system. See also: repeater and router.
>   broadcast
>   A transmission to multiple receiving stations simultaneously. A broadcast can be made, for example, over a multipoint line to all terminals that share the line, or over a network to all nodes.
>   broadcast storm
>   An incorrect packet broadcast onto a network that causes multiple hosts to respond all at once, typically with similar incorrect packets, which makes the storm's severity grow exponentially.
>   Brochure Web Site
>   Designed to generate revenues indirectly via online advertising, which helps refer buyers to products or services.
>   brouter
>   Abbreviation for Bridging/Router. A device which bridges some packets (i.e., forwards based on datalink layer information) and routes other packets (i.e., forwards based on network layer information). The bridge/route decision is based on configuration information. See also: bridge, router.
>   buffer
>   (1) In data transmission, a temporary storage area for information. A buffer slows data down to a speed that allow the receiving system to process it, without getting an error (or losing the data all together). A "buffer" can be found in either the sending or receiving device. (2) In cabling, a protective material on the fiber coating to protect the fiber-optic cable.
>   bug
>   A continuing problem in software or hardware. Also called an "undocumented feature" or a "character flaw". Most bugs are supposed to be worked out in the alpha- or beta-testing stage. But, as no person is perfect, no computer hardware or software is perfect either.
>   burst
>   In data communications, a sequence of signals counted as one unit in accordance with some specific criterion or measure.
>   bursty traffic
>   Data communications term referring to an uneven pattern of data transmission.
>   bus
>   (1) In data, the primary signal route, inside a computer, which can have several devices connected, letting them transmit and receive data at the same time (IBM's Micro Channel Architecture, for example). (2) In networks, the main (multiple access) network cable or line that connects network stations. Also refers to a network topology of multiple stations communicating directly with the same cable with terminators at both ends, like an Ethernet or token bus.
>   BUS
>   Broadcast and Unknown Server: This server handles data sent b and LE cClient to the broadcast MAC address (FFFFFFFFFFFF), all multicast traffic, and initial unicast frames which are sent by an LE Client.
>   Buttons
>   A rectangular graphic that is usually labeled with text to indicate its function. Buttons usually perform an instantaneous action to initiate or conclude a process.
>   byte
>   One character of information, usually 8 bits.

>   ## - C -

>   Back to Top
>   cable
>   The wires or groups of wires, usually surrounded by an external protective shell, that carry voice, data or video.
>   cable assembly
>   A completed cable, with its connectors and hardware, that is ready for installation.
>   cable loss
>   The total electrical signaling lost while traveling on a cable, attributed to a cable's shape, size, length and material.
>   cable patch panel
>   A passive device, frequently located in the intermediate distribution facility (IDF) or satellite equipment room, to offer easy circuit cross connections. It is used to connect two sets of wire (e.g., the wire from the IDF to the office and the wire between the IDFs).
>   cable system
>   All the cables and devices used to interconnect stations; often called the "premises network".
>   cable type
>   The specific kind of cable being used. Usually identified as "media." Different types of cables include: unshielded twisted pair (USP), Shielded Twisted Pair (STP), coaxial, and fiber optics. All cable types or media have their strengths and weaknesses. Some of the most important factors are cost, bandwidth, and connectivity.
>   cable-based LAN
>   A shared-media LAN that uses a cable as its transmission medium.
>   cache
>   A portion of a computer's RAM reserved to act as temporary memory for items read from a disk that become instantly available to the user.
>   cached
>   A piece of information that is retained in main memory instead of being stored on disk.
>   cannibalize
>   To strip a non-operational system for parts to repair another system and place it back into service.
>   capture
>   (1) The act of removing a token from the ring. (2) To grab information that is passed on a link.
>   carrier
>   (1) A long distance company which uses primarily its own transmission facilities, as opposed to resellers which lease or buy most or all transmission facilities from carriers. Many people refer to any type of long distance company, whether it has its own network or not, as a carrier, so the term is not as restrictive as it used to be. (2) An electrical signal sent at a specific frequency that can be adjusted or modified to carry data, voice or video. Also called carrier wave.
>   carrier detect
>   The ability to recognize carrier in preparation for transmitting data. Also the signal that signifies that carrier has been detected.
>   carrier frequency
>   Frequency of the carrier wave that is modulated to transmit signals.
>   Carrier Sense Multiple Access (CSMA)
>   A Local Area Network access technique in which multiple stations connected to the same channel are able to sense transmission activity on that channel and to defer the initiation of transmission while the channel is active. Similar to contention access.
>   Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)
>   CSMA that combines slotted TDM (to avoid having collisions occur a second time) with CSMA/CD. Works best if the time slot is short compared to packet length and if the number of stations is small.
>   Carrier Sense Multiple Access with Collision Detection (CSMA/CD)
>   A refinement of CSMA in which stations are able to detect the interference caused by simultaneous transmissions by two or more stations (collisions) and to retransmit colliding messages in an orderly manner. This is a basic principle of Ethernet. See also: 802.3 and Ethernet.
>   Cat 1
>   A cabling category that became obsolete in 1995. Could only handle voice and very slow data (1 Mbps). See also: Cat 2, Cat 3, Cat 4, Cat 5, and category cable.
>   Cat 2
>   A cabling category that became obsolete in 1995. Could only handle voice and very slow data. Faster that Cat 1 (4 Mbps), but still can no longer support data communications for a Local Area Network. See also: Cat 1, Cat 3, Cat 4, Cat 5, and category cable.
>   Cat 3
>   A cable type that is a 100 ohm shielded twisted pair (STP) that can carry 10 million bits per second (Mbps) on a Local Area Network. See also: Cat 1, Cat 2, Cat 4, Cat 5, and category cable.
>   Cat 4
>   A cable type that is a 100 ohm shielded twisted pair (STP) that can carry 20 million bits per second (Mbps) on a Local Area Network. See also: Cat 1, Cat 2, Cat 3, Cat 5, and category cable.
>   Cat 5
>   A cable type that is a 100 ohm shielded twisted pair (STP) that can carry 100-155 million bits per second (Mbps) on a Local Area Network. See also: Cat 1, Cat 2, Cat 3, Cat 4, and category cable.
>   category cable
>   Cable that complies with EIA/TIA TSB 36 and is rated category 1 thru 5. The higher the category number, the better the cable will be at carrying high speed signals. Category wire may be shielded or unshielded, but is always 100 ohm.
>   category devices
>   Devices, such as patch panels and wall jacks, that comply with EIA/TIA TSB40. See also: category cable.
>   CBR
>   Constant Bit Rate
>   CDDI
>   Acronym for Copper Distributed Data Interface.
>   CdPA
>   Called Party Address - The destination ATM End Station Address placed in the Setup message.
>   central office
>   The site where communications common carriers (telephone companies) terminate customer lines and house the equipment that interconnects these lines.
>   Certificate Authority
>   An entity that verifies the relationship between a Public Key and its associated identifier.
>   CGI
>   Computer programs that allow Web servers to interact dynamically with users. Many HTML pages that contain forms use a CGI program to process data submitted via an online form.
>   channel
>   (1) A transmission facility with defined bandwidth. (2) A trough for holding cables.
>   Channel loopback
>   A diagnostic test that forms the loop at the multiplexer's channel interface.
>   Channel Service Unit (CSU)
>   A component of Customer Premises Equipment (CPE) used to terminate a digital circuit at the customer site.
>   CHAP
>   Challenge Handshake Authentication Protocol. CHAP is a security protocol that is run over serial links. After PPP link establishment, the server sends a CHAP challenge to the client, then the client sends a response back to the server, which is an MD5 hash of the password. Finally, the server sends an "accept" or "reject" back to the client. CHAP provides more security than PAP by sending an MD5-encrypted password. CHAP may also periodically verify the connection, and the server may issue a challenge to the client on a periodic basis.
>   character set
>   A collection of characters, such as ASCII or EBCDIC, used to represent data in a system. These character are typically available on a keyboard or through a printer.
>   characteristic attribute
>   A system management concept for an attribute that can be changed or modified by a director, thus affecting the behavior of that entity.
>   CHARGEN
>   Acronym for Character Generator Protocol.
>   Check boxes
>   Used when alternatives are not mutually exclusive, or may be applied simultaneously, such as type styles: type can be both bold and italic at the same time.
>   Checksum
>   A number or word that is used to verify the accuracy or reliability of data transfer. Analagous to, and usually more reliable than, comparing file sizes after copying a file from one disk or system to another.
>   CIR
>   Committed Information Rate
>   circuit
>   (1) The physical cable or wire used in data, voice or video communications. (2) A term that refers to a logical stream of data between two hosts on the network. For example, one physical link may have several virtual circuits running over it.
>   circuit switching
>   A communications method in which a dedicated path is identified by switching a signal to the wires that will connect the two hosts. The telephone system is an example of a circuit switched network.
>   Clear To Send (CTS) (EIA RS-232-C)
>   A time delay inserted after a data terminal equipment requests to send data to allow the modem to turn carrier on and establish equalization and synchronization, also known as RTS-CTS delay and turnaround delay.
>   cleared call
>   A virtual circuit that has been disconnected.
>   client
>   A module that requests and uses the services of another module, generally known as the server.
>   client-server model
>   A common way to describe the concepts and rules behind many network protocols. The client software in a user's system, requests and uses the server's service(s). See also: client, server, Domain Name System, Network File System, File Transfer Protocol, Telnet, and Simple Mail Transfer Protocol.
>   clock
>   The timing signals used in data communications or the source of those timing signals.
>   clocking
>   Repetitive, regularly timed signals used to control data transmissions.
>   CMOS
>   Acronym for Complementary Metal Oxide Semiconductor.
>   CO
>   Acronym for Central Office. Location where communications common carriers terminate customer lines and house the equipment that interconnects these lines.
>   coaxial cable
>   A transmission medium noted for its wide bandwidth and for its low susceptibility to interference. It is made up of an outer woven conductor which surrounds the inner conductor. The conductors are commonly separated by a solid insulating material.
>   coaxial converter
>   A protocol converter designed to be used between 3270 control units and attached asynchronous devices. It uses coaxial cable to connect to the control unit.
>   collision
>   The result of two (or more) LAN stations attempting to use the same transmission medium at the same time.
>   collision domain
>   In Ethernet, the logical single network in which all interfaces to the network receive all transmissions and in which all collisions must be detected.
>   common carrier
>   An organization in the business of providing regulated telephone, telegraph, telex, and data communications services.
>   common domain
>   An administrative domain which is not a member of a higher-level domain. A common domain is the highest level in the domain name hierarchy. For example, MIL, GOV, COM, EDU.
>   communication line
>   Any medium, such as a wire or a circuit, that connects remote stations for the purpose of transmitting/receiving information.
>   communications adapter
>   A device, attached to a System 34, 36, or 38 host, that allows communications over RS-232 lines to remote devices.
>   communications controller
>   A dedicated computer, with special processing abilities, for organizing and checking data ,and for passing traffic to and from multiple remote terminals or computers.
>   communications protocol
>   The rules used to control the orderly exchange of information between stations on a data link or on a data network or system. Also called line discipline or protocol.
>   computer network
>   An interconnection of computer systems, terminals, communications facilities, and data collecting devices.
>   concentrator
>   A communications device that offers the ability to concentrate many lower-speed channels into, and out of, one or more high-speed channels.
>   configuration
>   Settings that control the way a system or service will operate. Also the combined services and/or equipment that make up a communications system.
>   congestion
>   Too much traffic for a given circuit, router, gateway, or host.
>   connection
>   A physical point-to-point network link connecting two devices. Also the logical link that supports communications between two users or elements.
>   connectionless
>   The data communication method in which communication occurs between hosts with no previous setup. Packets between two hosts may take different routes, as each is independent of the other. UDP, IPX and IP are connectionless protocols
>   console
>   The device used by the operator, system manager, or maintenance technician to monitor or control computer, system, or network performance.
>   contention
>   The facility provided by the dial network or a data PABX which allows multiple terminals to compete (or contend) on a first-come, first-served basis for a smaller number of computer ports.
>   Control Access Unit (CAU)
>   A token ring device that manages Lobe Access Modules (LAM).
>   control character
>   A character whose occurrence in a particular context initiates, modifies, or stops a control function.
>   Cookie
>   A network tool used to detect when a user's computer visits Web sites and networks.
>   Copper Distributed Data Interface (CDDI)
>   A variation of FDDI that uses Category 5 unshielded twisted pair copper wire.
>   core gateway
>   One of a set of gateways (routers) operated by the Internet. The core gateway system forms a central part of Internet routing in that all groups must advertise paths to their networks from a core gateway, using the Exterior Gateway Protocol (EGP).
>   COS
>   Class of Service
>   countermeasure
>   A safeguard, or countermeasure, is anything that lessens the threat a vulnerability presents
>   CQ
>   Custom Queuing
>   CRC
>   Acronym for Cyclic Redundancy Check.
>   Cryptographic Key
>   A password or table needed to decrypt encoded data.
>   CSMA
>   Acronym for Carrier Sense Multiple Access.
>   CSMA/CA
>   Acronym for Carrier Sense Multiple Access with Collision Avoidance.
>   CSMA/CD
>   Acronym for Carrier Sense Multiple Access with Collision Detection.
>   CSU
>   Acronym for Channel Service Unit.
>   CTS
>   Acronym for Clear To Send.
>   cursor
>   A movable underline, rectangular-shaped block of light, or an alternating block of reversed video on the screen of a display device, usually indicating where the next character is to be entered.
>   Cursors (or pointers)
>   A component of graphic interfaces that indicate the point of action or insertion on the screen, often acting as a virtual manipulator or hand tool for moving and editing on-screen objects. Cursors are also used to indicate the state of the system.
>   Customer Premise Equipment (CPE)
>   Equipment, usually including wiring, located within the customer's part of a building.
>   cut through
>   The establishment of a complete path for data, video or audio communications.
>   Cyclic Redundancy Check (CRC)
>   An error detection scheme. A number is derived from the data that will be transmitted. By recalculating the CRC at the remote end and comparing it to the value originally transmitted, the receiving node can detect errors.

>   ## - D -

>   Back to Top
>   DA
>   Acronym for Destination Address.
>   daemon
>   A UNIX term referring to a process that is not connected with a user but performs services, such as a mail daemon. The equivalent VMS term is "detached process".
>   DAS
>   Acronym for Dual Attachment Station. A station with two connections to an FDDI network.
>   data communications
>   the interchange of data messages from one point to another over communications circuits.
>   data communications equipment
>   The equipment which provides the functions of interfacing between data terminal equipment and a equipment communications channel DCE is normally a modem.
>   data encryption
>   A method of making data "secure" using a cryptographic algorithm designed by the NBS (now NIST) to encipher and decipher data using a standard (DES) 64-bit key. See also: encryption.
>   Data Encryption Key (DEK)
>   Used for computing encryption of information. DEKs are created separately for each transmitted session.
>   Data Encryption Standard (DES)
>   A commonly-used standard encryption method.
>   data link
>   A transmission path directly connecting two or more stations (a station may be a terminal, terminal controller, front end processor, or other type of digital equipment)
>   data link layer
>   The OSI layer (Layer 2) that is responsible for data transfer across a single physical connection, or series of bridged connections, between two network entities.
>   Data Scrubber
>   A type of Internet privacy service that conceals the identity of Web users.
>   data set ready
>   An RS-232 modem interface control signal (sent from the modem) to the DTE on pin which indicates that the modem is connected to the telephone circuit.
>   data terminal
>   A station in a system capable of sending and/or receiving data signals.
>   data terminal ready
>   An RS-232 modem interface control signal (sent from the DTE to the modem on pin 20) that indicates that the DTE is ready for data transmission and requests that the modem be connected to the circuit.
>   data transmission
>   The sending of data from one place for reception elsewhere.
>   data-over-voice
>   A frequency division multiplexing technique which combines data and voice on the same line by assigning a portion of the unused bandwidth to the data.
>   Database
>   A collection of related pieces of digital information that can be stored and retrieved.
>   datagram
>   The unit transmitted between a pair of Internet modules. The Internet Protocol provides for transmitting blocks of data, called datagrams, from sources to destinations. See also: IP.
>   DCD
>   Acronym for Data Carrier Detect (Protocol Standard EIA-RS-232).
>   DCE
>   (1) Acronym for Distributed Computing Environment. (2) Acronym for Data Communications or Data Circuit Terminating Equipment. A communications device that can establish, maintain, and terminate a connection (a modem, for example). A DCE may also provide signal conversion between the data terminal equipment (DTE) and the common carrier's channel. Contrast DTE. (Protocol Standard EIA RD-232).
>   deadlock
>   A term used in a multi-user environment. When one user holds a lock on a resource and is waiting for a second resource to free up at the same time, a second user has the reverse situation on the same resources. The deadlock must be broken by arbitrarily picking one of the users and releasing its current lock. The deadlock is also known as a deadly embrace.
>   decimal
>   A digital system that has ten states, 0 through 9.
>   Default buttons
>   A screen button with a heavy outline used to indicate the most likely action to be taken. Default buttons are usually linked to the Return key of the keyboard; to initiate the default action the user can just hit the Return key.
>   default route
>   A routing table entry which is used to direct any data addressed to any network numbers not otherwise listed in the routing table. Many times a default route is listed as a "0.0.0.0".
>   Denial of Service Attacks (DoS)
>   Network attacks that attempt to bring the network down by drowning it with useless traffic.
>   DES
>   Data Encryption Standard
>   designated router
>   A DNA or OSPF routing concept and the term used in the Open Version of the Shortest Path First protocol. A given circuit (such as an Ethernet) will have a designated router. This router is used by end nodes to forward all packets that need routing decisions. The designated router is like the "master" router. This router generates routing tables based on the quality of the routes.
>   destination address
>   The portion of a message that indicates where it is to be sent (typically a series of characters or bits).
>   Destination Service
>   The Access Point (DSAP) The address for the destination user of a service. A remote IPX process would be considered the DSAP from the point of view of the local data link module.
>   DF
>   Acronym for Don't Fragment. An IP flag indicating that this packet should not be fragmented. The DF flag is used to isolate network problems.
>   DFC
>   Acronym for Data Flow Control.
>   DFS
>   Acronym for Distributed File Service or System.
>   DHCP
>   Dynamic Host Configuration Protocol is an industry-standard protocol that automatically assigns IP addresses and configuration information to computers.

>   DHCP frees an administrator from having to assign an IP address to each client manually.

>   DHCP is specified by Internet Engineering Task Force (IETF) Requests for Comments RFC 1542, RFC 2131, and RFC 2132.
>   Dialog boxes
>   Special windows that pop up to provide information or choices to the user. Dialog boxes are usually modal, that is, they must be dismissed before further action can take place. Some dialog boxes provide many buttons, pop-up menus, or other choices; others may just contain a text message with an "OK" button used to dismiss the dialog box.
>   Digital Signature
>   Any identifier or authentication technique attached to or associated with an electronic document that is intended by the party using it to have the same force and effect as the signing party's manual signature.
>   DISA (Data Interchange Standards Association
>   A not-for-profit organization that offers a variety of outreach initiatives and extensive educational programs for every e-commerce endeavor.
>   Discount Rate
>   A percentage of each sale that the bank charges for processing credit card transactions. Also known as a bank rate.
>   Disintermediation
>   Refers to the collapse of the supply chain. It is the phenomenon whereby some manufacturers are passing up the intermediary wholesalers and retailers by offering their products directly to consumers via e-commerce.
>   disk
>   An electromagnetic storage medium for digital data.
>   Disk Operating System (DOS)
>   A program or set of programs that tells a disk-based computer system how to schedule and supervise work, to manage computer resources, and to operate and control its peripheral devices.
>   disk server
>   A LAN device that lets multiple users access sections of its disks for creating and storing files. Contrast with a file server, which allows users to share files.
>   Distributed Computing Environment (DCE)
>   An architecture of standard programming interfaces, conventions, and server functionality for distributing applications across networks of different computers.
>   distributed data processing
>   The processing of information in separate locations as on a local area network. This is a more efficient use of processing power, since each CPU can do a certain task.
>   distributed file service
>   A DEC product similar to the Network File System (NFS). Both let remote files look like they are locally mounted on a workstation.
>   distributed naming service
>   A network-based service to let a user find the current address of a given resource such as a printer or file system, particularly when the service is provided on several separate resources.
>   DIX Ethernet
>   Acronym for DEC Intel Xerox Ethernet; also called Ethernet 2. See also: Ethernet.
>   DNS
>   The method used to convert Internet names to their corresponding Internet numbers.

>   A DNS is a distributed service used to translate a domain name into an IP address.

>   The acronym DNS stands for different things to different people. The most common breakdowns are Domain Name System, Domain Name Service, and Domain Name Server
>   domain
>   A zone or part of a naming hierarchy. An Internet domain name consists of a sequence of names separated by periods, as in "roadie.cs.arg3.com."
>   domain name server
>   A computer that converts names, such as hammer.is.arg3.com or nic.is.arg3.com, to their corresponding Internet numbers, like 192.153.186.66 or 192.136.118.11. It lets users Telnet or FTP to the name instead of the number.
>   Domain Name System (DNS)
>   The distributed name and address mechanism used in the Internet.
>   domain specific part
>   The part of the OSI address that is locally assigned.
>   dot address
>   Dot address refers to the common notation for IP addresses of the form 0.0.0.0, where each zero represents one decimal byte of a four byte IP address. Also called dotted decimal notation. See also: IP address.
>   dotted decimal notation
>   The method of writing the Internet address. See also: dot address.
>   download
>   To make a copy of a file from a central service (or server) onto a local computer. Contrast with a load and execute operation on a LAN.
>   downtime
>   The time when a system is not operating. Downtime calculations could include the whole system or part of a system.
>   drop
>   (1) noun, A portion of cable that connects a user station to a network. (2) noun, Also refers to the jack that is the point of contact for the cable drop. The user sees a drop as a network connection. (3) verb, To logically disconnect part or all of a signal whether intentionally or unintentionally.
>   DSR
>   Acronym for Data Set Ready.
>   DSU
>   Acronym for Digital Service Unit. A device that converts the user's data stream to bipolar format for transmission.
>   DSU/CSU
>   Acronym for Data Service Unit/Channel Service Unit. A Data Service Unit/Channel Service Unit connects an external digital circuit to a digital circuit on the customer's premises. The DSU converts data into the correct format, while the CSU terminates the line, conditions the signal, and participates in remote testing of the connection.
>   DTL
>   Designated Transit List: A list of nodes and optional link IDs that completely specify a path across a single PNNI peer group.
>   dual attachment station (DAS)
>   FDDI term for a node that is attached to both the primary and secondary fiber optic rings. Contrast with a single attached station that is connected to the ring via a concentrator.
>   dumb terminal
>   A term used to describe an asynchronous, ASCII terminal. Although it may be intelligent in many of the functions it provides, it uses no communication protocol. A dumb terminal may operate at speeds up to 19.2 Kbps.

>   ## - E -

>   Back to Top
>   E-mail
>   Abbreviation for Electronic mail; also email.
>   E-mail address
>   The domain-based or UUCP address that is used to send electronic mail to a specified destination. For example, an editor's address is "gmalkinxylogics.com
>   echo
>   A signal that has been reflected or otherwise returned with sufficient magnitude and delay to be perceived by the originator.
>   echo request
>   ICMP message (type 8) that has the remote site echo the received data using the echo reply (type 0) message. Used in timing the round-trip transmission.
>   EDP
>   Acronym for Electronic Data Processing.
>   EDS
>   Acronym for Electronic Data Systems. Ross Perot's former company that is now owned by General Motors.
>   EIA
>   A standards organization in the U.S. specializing in the electrical and functional characteristics of interface equipment.
>   EIA-232
>   Standard interface definition for serial devices. Better known as RS-232. RS-232-E is the current version of the standard.
>   EIA/TIA
>   Acronym for Electronic Industries Association/Telecommunications Industries Association.
>   EIA/TIA 568
>   The commercial building wiring standard. It defines a generic wiring system for a multi-product, multi-vendor environment. Widely considered the most important standard for building wiring.
>   EIA/TIA 568A
>   The recommended 8 pin, modular jack (RJ45) pin configuration defined in EIA Standard 568.
>   EIA/TIA 568B
>   An alternate RJ45 pin configuration defined in EIA Standard 568. Equivalent to AT&T 256A.
>   EISA
>   Acronym for Extended Industry Standard Architecture. PC bus system that is an alternative to IBM's Micro Channel Architecture (MCA). The EISA architecture, backed by an industry consortium headed by Compaq, is compatible with the IBM AT bus; MCA is not.
>   electrically erasable programmable read-only memory (EEPROM)
>   A memory that can be electronically programmed and erased, but which does not need a power programmable read-only source to hold the data memory.
>   ElectroMagnetic Interference (EMI)
>   The energy given off by electronic circuits and picked up by other circuits; based on the type of device and operating frequency. EMI effects can be reduced by shielding and other cable designs. Minimum acceptable levels are detailed by the FCC.
>   Electronic Business Communities (EBCs)
>   Refers to online communities where businesses, consumers, and product suppliers cooperate in a synergistic, flowing model of supply and demand.
>   Electronic Commerce (e-commerce)
>   Describes a practice used by an increasing number of individuals and businesses to conduct commercial transactions while connected to the Internet.
>   Electronic Data Interchange (EDI)
>   A standard system of exchanging order and billing information between computers in different companies.
>   Electronic Data Interchange (EDI)
>   The transfer of digital data between different companies using the Internet and other digital technologies.
>   Electronic Draft Capture (EDC)
>   A system in which the transaction data is captured at the merchant location for processing and storage.
>   electronic mail (E-mail)
>   A system whereby a computer user can exchange messages with other computer users (or groups of users) via a communications network. Electronic mail is one of the most popular uses of the Internet. [Source: NNSC]
>   emulation
>   The imitation of a computer system, performed by a combination of hardware and software, that allows programs to run on otherwise incompatible systems.
>   encapsulation
>   (1) The technique used by layered protocols in which a layer adds additional header information to the Protocol Data Unit (PDU) from an equivalent layer of another protocol; i.e., IPX encapsulated in IP. (2) Tunneling. (3) Encasing a splice in a protective material to make it watertight.
>   encryption
>   Encryption is the manipulation of a packet's data in order to prevent anyone but the intended recipient from reading that data.
>   Encryption
>   Technology that encodes computer files to protect peoples' privacy.
>   end system
>   An OSI system on which applications run. An end system has full seven-layer OSI functionality. Basically equivalent to an Internet host or a LAN user node.
>   Escrow Agent
>   An entity that holds encryption keys for other users.
>   Ethernet
>   (1) A 10-Mbps, coaxial standard for LANs, initially developed by Xerox and later refined by Digital, Intel and Xerox (DIX). All nodes connect to the cable where they contend for access via CSMA/CD. (2) Slang for the coaxial cable that carries the standard. (3) 802.x, Local Area Network, token ring.
>   Ethernet controller
>   A device that controls a computer's access to Ethernet services. The CSMA/CD protocols are used by the controller to free the CPU.
>   Ethernet meltdown
>   The result of an event that causes saturation, or near saturation, on an Ethernet. It usually comes from illegal or misrouted packets and normally runs for a short time only.
>   Ethernet version 2.0
>   The second version of the original specification for Ethernet, differing slightly from the IEEE 802.3 standard.
>   EtherTalk
>   Ethernet cable plant running AppleTalk packets.
>   ethertype
>   The field in Version 2.0 of Ethernet that indicates the protocols carried in the Ethernet frame.
>   EXEC
>   Abbreviation for executable.
>   Extended Industry Standard Architecture (EISA)
>   A bus architecture for desktop computers that provides a 32-bit data passage while maintaining compatibility with the ISA or AT architecture. It was developed as an alternative to Micro Channel Architecture (MCA).
>   Exterior Gateway Protocol (EGP)
>   A hop-oriented, reachability, routing protocol used by routers in an Internet. The routing information is distributed to the routers which connect autonomous systems. EGP is used in the Internet core system.
>   Ezine
>   An online, digital magazine.

>   ## - F -

>   Back to Top
>   fast Ethernet
>   See 100 Base VG and 100 Base X.
>   fault
>   A condition that causes any physical component of a system to fail to perform in acceptable fashion.
>   fault tolerance
>   The ability of a program or system to operate properly even if a failure occurs.
>   FCS
>   Acronym for Frame Check Sequence. The CRC remainder sent at the end of a frame.
>   FDDI
>   Acronym for Fiber Distributed Data Interface.
>   FDDI II
>   Acronym for Fiber Distributed Data Interface.
>   FDQN
>   Fully Qualified Domain Name.

>   FQDNs are made up of text labels and are separated by periods or dots. The label at the far-left portion of the FQDN is most specific, and usually refers to a particular machine.

>   As you move to the right, past each dot, the text labels that follow become less and less specific. These labels identify the different domains that can belong to the information in the far-left label.

>   The far-right label is the least specific label, and often indicates the country or organization that computer is in.
>   fiber distributed data interface (FDDI)
>   A high-speed (100Mb/s) LAN standard. The underlying medium is fiber optics, and the topology is a dual-attached, counter- rotating token rings. FDDI II is a draft standard for revising FDDI to carry multi-media signals at 100 Mbps. See also: Local Area Network, token ring.
>   fiber optics
>   A technology that uses light as a digital information carrier. Fiber optic cables are a direct replacement for conventional cables and wire pairs. They occupy far less physical space and are immune to electrical interference.
>   FIDDI
>   Acronym for Fiber Distribution Data Interface.
>   file transfer
>   The copying of a file from one computer to another over a network or dial-up circuit. See also: file transfer protocol.
>   File Transfer Protocol (FTP)
>   A TCP/IP protocol that lets a user on one computer access and transfer files to and from another computer over a network. FTP is usually the name of the program the user invokes to accomplish this task.
>   File Transfer Protocol (FTP)
>   A client-server protocol that allows a user on one computer to transfer files to and from another computer over a TCP/IP network. Also the client program the user executes to transfer files.
>   filter
>   A circuit or process designed to transmit signals or data within one or more parameters and to block others.
>   FOIRL
>   Fiber Optic Inter Repeater Link. An IEEE standard for fiber optic connections between Ethernet repeaters. See also: 10 Base F.
>   FOOBAR or FUBAR
>   Acronym for Fouled Up Beyond All Recognition.
>   FQDN
>   Acronym for Fully Qualified Domain Name.
>   FR
>   Acronym for Frame Relay.
>   fragment
>   A piece of a packet. When a router is forwarding an IP packet to a network that has a maximum packet size smaller than the forwarded packet size, it is forced to break up that packet into multiple fragments.
>   frame
>   A series of bytes of data encapsulated with a header and trailer.
>   frame check sequence
>   The CRC remainder transmitted at the end of a frame.
>   frame error rate
>   The number of errors on a frame. This measurement is similar to bit error rate; however, it measures larger blocks of data called frames. The term frame is often used interchangeably with packet, although technically, a packet refers to data from the network layer of the protocol stack.
>   frame relay
>   A faster form of packet switching that is accomplished with smaller packet sizes and less error checking.
>   frame status
>   A token ring field that indicates the address on a packet has been recognized by a station and the data has been copied.
>   Free On Board (FOB)
>   Term that defines where titles to a goods change hands.
>   frequency
>   The number of times per second a signal regenerates itself at a peak amplitude. It can be expressed in hertz (Hz), kilohertz (kHz), megahertz (MHz), etc.
>   FTP
>   Acronym for File Transfer Protocol.
>   full duplex
>   A circuit that lets messages flow in both directions at the same time. Contrast with half-duplex where only one side can transmit at a time.

>   ## - G -

>   Back to Top
>   gateway
>   The original Internet term for a router, or more accurately an IP router. In current usage, "gateway" and "application gateway" refer to translating systems that convert data traveling from one environment to another. See also: router.
>   Gb
>   Acronym for gigabit. One billion bits of information.
>   GB
>   Acronym for gigabit (or gigabyte) backbone. The gigabit backbone is an effort to increase the speed of the Internet to one Gbps.
>   Gbyte
>   Acronym for Gigabyte. One billion bytes of data.
>   giga
>   A prefix that means "one billion".
>   gigabit
>   One billion bits. See also: bit.
>   gigabyte (GB)
>   One billion bytes. Used to describe an amount of information. See also: byte.
>   Gopher
>   A corruption of "Go-for". A primitive web search tool/protocol/interface.
>   GRE
>   Generic Routing Encapsulation (GRE)is used to tunnel many different protocols over IP and NON IP networks. The GRE tunneling works by encapsulating a network protocol within packets carried by a second network
>   GUID (Global Unique Identifier)
>   A more advanced type of cookie. A number used to detect when a user's computer visit Web sites and networks.

>   ## - H -

>   Back to Top
>   Hacker
>   A slang term for an amateur programmer who lacks formal training, which has also been used to describe individuals who gain unauthorized access to computer systems for the purpose of stealing and corrupting data.
>   half duplex
>   A circuit for transmitting or receiving signals in one direction at a time.
>   HDLC
>   Acronym for High Level Data Link Control. A bit-oriented data link control that is functionally similar to ADCCP.
>   Hertz (Hz)
>   International standard unit of frequency. Replaces the identical, older "cycles-per-second."
>   heterogeneous network
>   A network of different network protocols or kinds of computers.
>   hexadecimal
>   A number system with 16 members represented by 0 through 9, followed by A through F. Also known as "base 16" or "hex". Each character identifies four bits or a half-byte.
>   - decimal 12 = C in hex
>   - decimal 16 = 10 in hex
>   - decimal 255 = FF in hex
>     home run
>     A cabling method in which each cable is run directly to the workstation outlet without intermediate cross connections.
>     hop
>     A term used in vector distance routing. A hop is one data link. A path to the final destination on a net is a series of hops away from the origin.
>     horizontal distribution system
>     The fixed cable system that connects from the intermediate distribution facility to the user telecommunications outlet (wall jack).
>     host
>     (1) A computer that provides services directly to users; i.e., the user's computer. In TCP/IP, an IP addressed device. (2) A large computer that serves many users; i.e., a minicomputer or mainframe.
>     host address
>     The part of an Internet address that designates which node on the (sub)network is being addressed; also called host number.
>     host computer
>     See host.
>     host field
>     The bit field in an Internet address used for denoting a specific host.
>     host name
>     The name (usually an alias) given to a machine.
>     host server
>     A device that connects to a Local Area Network (LAN). The host server allows a computer that can't support LAN protocols to connect to the LAN and, hence, be able to access the LAN's resources; it acts like a translator.
>     HSSI
>     High-Speed Serial Interface. A serial communications connection that operates at up to T1 speeds (1.544 Mbps).
>     hub
>     A device which connects to several other devices usually in a star topology; also called concentrator, multiport repeater or Multi-station Access Unit (MAU).
>     Hz
>     See Hertz.

>     ## - I -

>     Back to Top
>     I/O
>     Acronym for Input/Output.
>     ICMP
>     The Internet Control Message Protocol resides in the Internet layer and is implemented in the IP packets of both hosts and routers. The internet layer is the same as the network layer of the OSI reference model.

>     There are two basic types of ICMP messages: ICMP Error, and ICMP Query messages.

>     Request for Comment (RFC) 792 defines 13 ICMP messages that can be identified by the ICMP Message Type field
>     Icons
>     Graphic representations of objects in the computer interface, including folders, documents, trash cans, mail boxes, applications, storage media, and other hardware attached to the computer or the computer network.
>     IEEE 802
>     A family of IEEE standards for network communications. The number identifies the committee that defines a standard, and has come to define the standard as well.
>     IEEE 802.1
>     The IEEE committee that defines the LAN management and bridging standards.
>     IEEE 802.2
>     A data-link layer standard used with 802.3, 802.4 and 802.5.
>     IEEE 802.3
>     A physical-layer standard specifying a linear (bus) LAN via the CSMA/CD access method. Starlan and Ethernet follow this standard. It usually operates at 10 Mbps.
>     IEEE 802.4
>     A physical-layer standard specifying a linear (bus) LAN with a token-passing access method. ARCNET and MAP follow this standard. It usually operates at 10 Mbps.
>     IEEE 802.5
>     A physical-layer standard that specifies a ring topology LAN with a token-passing access method. IBM's token ring follows this standard. It commonly operates at 4 Mbps or 16 Mbps.
>     IETF
>     Internet Engineering Task Force
>     IISP
>     Interim Inter-switch Signaling Protocol - A routing information protocol that enables static routing in a multi-vendor ATM network.
>     ILMI
>     Integrated Link Management Interface: An ATM forum defined specification for network mangement functions between an end user and a public or private network and between a public network and a private netowrk. This is based on a limited subset of SNMP capabilities.
>     in-band
>     A method of sending management and/or control signals on the same frequency (in the same band) as data signals; contrast with out-of-band.
>     Infomediaries
>     A type of portal site. Yahoo! and AOL are sometimes referred to as infomediaries.
>     Information and Content Exchange (ICE)
>     A protocol for the automatic, controlled exchange and management of online assets between business partners.
>     Integrated Circuit (IC)
>     Also called a chip, an IC is a small electronic device made out of a semiconductor material.
>     Integrated Services Digital Network (ISDN)
>     An emerging technology that is beginning to be offered by the telephone carriers of the world. ISDN combines voice and digital network services into a single medium or "wire".
>     interior gateway routing protocol
>     A Cisco proprietary routing protocol. This vector-distance protocol used to automatically update routing tables.
>     intermediate system
>     An OSI system that performs routing and relaying functions in order to provide paths between end systems; functionally similar to an Internet Router.
>     Internet (Note the capital "I".)
>     The largest Internet in the world including large national backbone nets (such as MILNET, NSFNET, and CREN) and many regional (and local) networks world-wide. The Internet uses the TCP/IP suite. Networks with only E-mail connectivity are not considered on the Internet. While an Internet is a network, the term "Internet" is usually used to refer to a collection of networks interconnected with routers. See also: network.
>     Internet address
>     An assigned number that identifies a host in the Internet. It has two or three parts or fields: network number, optional subnet number, and host number.192.136.118.3.
>     Internet Architecture Board (IAB)
>     The technical body that oversees the development of the Internet suite of protocols (commonly referred to as TCP/IP).
>     Internet Assigned Numbers Authority (IANA)
>     The central registry for various Internet protocol parameters, such as: port, protocol and enterprise numbers, and options, codes and types.
>     Internet autonomous system
>     A set of systems and networks that fall under a single administrative authority, and communicate via one point to other autonomous systems.
>     Internet Control Message Protocol (ICMP)
>     The protocol that handles errors and control messages at the IP layer. ICMP is actually a part of the IP protocol layer. It can generate error messages, test packets, and informational messages related to IP.
>     Internet Engineering Steering Group (IESG)
>     The IESG is composed of the IETF Area Directors and the IEFT Chair. It provides the first technical review of Internet standards and is responsible for day-to-day "management" of the IEFT.
>     Internet Engineering Task Force (IETF)
>     One of the task forces of the IAB, responsible for solving short-term engineering needs of the Internet; it includes more than 40 Working Groups.
>     Internet gateway
>     A designated hardware device that provides access to the Internet. The device may be a gateway router and/or wide area network to the Internet. A gateway connects a local/metropolitan or wide area network to the Internet.
>     Internet Network Information Center (InterNIC)
>     The organization in the Internet that is responsible for the dissemination of Internet information. In addition, the InterNIC registers and manages Internet addresses and domain names.
>     Internet Protocol (IP)
>     The Internet protocol is the second layer of a four-layer protocol and the network layer for the TCP/IP protocol suite. This layer is responsible for router-to-router communications. It is a connectionless, best-effort, packet-switching protocol that offers a common layer over dissimilar networks. See also: packet switching, Request For Comments, TCP/IP Protocol Suite.
>     Internet protocol suite
>     A four-layer protocol stack, defined by the Internet Architecture Board. The Internet protocol suite has become the most popular set of network protocols.
>     Internet Server
>     A server (a computer) that provides end users access to the Internet. Popular Internet services provided by a server include: E-mail, TFTP, FTP, Telnet, and hypertext.
>     Internet Society (ISOC)
>     The Internet Society is a non-profit, professional membership organization that facilitates and supports the technical evolution of the Internet, as well as stimulating interest in and educating the scientific and academic communities, industry and the public about the technology, uses and applications of the Internet, and promotes the development of new applications for the system.
>     Internetwork
>     (1) noun, A collection of data links and the network layer programs for routing among those data links. (2) verb, To connect different networks and systems together, usually with one protocol suite.
>     InterNIC
>     Acronym for Internet Network Information Center. InterNIC controls the assignment of IP addresses worldwide
>     Interrupt Request (IRQ)
>     A method used in PC's, and other computer architectures, to let a sub-device, like a serial port or network adapter, request service from a central processor.
>     IO
>     Acronym for Input/Output (sometimes I/O).
>     IP
>     Acronym for Internet Protocol.
>     IP address
>     The, currently, 32-bit address defined by the Internet Protocol. It is usually represented in dotted decimal notation. See also: dot address, Internet address, Internet Protocol, network address, subnet address, host address.
>     IP datagram
>     The fundamental unit of information passed across network using the Internet Protocol.
>     IP router
>     An intelligent device which routes packets based on an IP address and routing tables.
>     IP-FDDI
>     Acronym for Transmission of IP over FDDI.
>     IP-SLIP
>     Acronym for Transmission of IP over Serial Line Interface Protocol.
>     IPX
>     Acronym for Internetwork Packet eXchange.
>     IRQ
>     Acronym for Interrupt Request.
>     IS-IS
>     Acronym for Intermediate System to Intermediate System protocol. The OSI protocol by which intermediate systems exchange routing information.
>     IS-IS
>     Acronym for Intermediate System to Intermediate System protocol. The OSI protocol by which intermediate systems exchange routing information.
>     ISA
>     Industry Standard Architecture
>     ISDN
>     Acronym for Integrated Services Digital Network.
>     ISO
>     Acronym for International Organization for Standardization.
>     ISOC
>     The Internet Society is a non-profit, non-governmental, international, professional membership organization. It focuses on: standards, education, and policy issues.
>     ITU
>     International Telecommunications Union

>     ## - J -

>     Back to Top
>     JavaScript
>     A scripting language developed by Netscape to enable Web authors to add dynamic, interactive content to their web sites.

>     ## - K -

>     Back to Top
>     kb
>     Acronym for kilobit. One thousand bits.
>     KB
>     Acronym for kilobyte. One thousand bytes.
>     kbps
>     Acronym for kilobits per second. One thousand bits per second.
>     kbyte
>     Acronym for kilobyte. One thousand bytes.
>     keep alive message
>     A message sent over a network link during periods when there is no traffic between users. The message tells the remote node that the local node remains operational.
>     kludge
>     An improvised solution.

>     ## - L -

>     Back to Top
>     L2F
>     Layer 2 Forwarding (L2F) was Cisco?s answer to routing non-IP packets across an IP network. Developed about the same time that Microsoft was developing PPTP, L2F permits tunneling of link-layer frames, passing protocol-level packets through a virtual tunnel. L2F is still supported but will be replaced by L2TP.
>     L2TP
>     The Layer 2 Tunneling Protocol (L2TP) was a group effort of Cisco, Microsoft, and other companies to come up with one protocol with the advantages of both L2F (Cisco) and PPTP(MS)
>     LAN
>     Acronym for Local Area Network.
>     LAP-D
>     Acronym for Link Access Protocol for the D channel.
>     LAPB
>     Acronym for Link Access Protocol-Balanced.
>     layer
>     A modular portion of a stacked protocol that consists of one or more semi-independent protocols. Each layer builds on the layer beneath it and feeds information to the protocols in the layers above it. TCP/IP has five layers of protocols, and OSI has seven.
>     layering
>     That aspect of a network architecture which separates functions into distinct functional levels, which communicate individually with like levels in a distant node.
>     lays
>     The twists in a twisted pair cable.
>     leased line
>     Any circuit or combination of circuits designated to be at the exclusive disposal of a given subscriber; also called private line or full period line.
>     LEC
>     Acronym for Local Exchange Carrier.
>     LECS
>     LAN Emulation Configuration Server: This implements the policy controlled assignment of individual LE clients to different emulated LANs by providing the LES ATM addresses.
>     LED
>     Acronym for Light Emitting Diode.
>     leg
>     A segment of cable that connects any two points on a longer circuit.
>     level
>     An expression of the relative signal strength as measured at any finite point in a communications circuit, as compared to a standard.
>     line
>     An electrical path between two points, usually a telco CO and the end user.
>     line driver
>     A short-haul communications device for overcoming the RS-232 alleged distance limitation.
>     link
>     The physical interconnection between two systems (sometimes called nodes) in a network. A link may consist of a data communications circuit or a direct cable connection.
>     link access protocol
>     An unbalanced version of HDLC in which the communications lines have a single, permanent console which must initiate all data transfer actions.
>     link access protocol-balanced
>     A version of HDLC in which either of the two connected stations on the communication line may initiate a data transfer operation.
>     link layer
>     Acronym for Data Link Layer.
>     link layer access method
>     The algorithm used on a PC/TCP Local Area Network that determines when a network interface is allowed to transmit.
>     link protocol
>     A set of rules for data communication over a data link specified in terms of transmission code, transmission mode, control procedures, and recovery procedures.
>     link state packet
>     A routing control information message exchanged in a Phase V DECnet or in OSI IS-IS routing domains.
>     link state protocol
>     Any routing protocol that recognizes speed, reliability, and other functional characteristics of the communications link.
>     Linux
>     A popular implementation of UNIX that is freely distributed and runs on a number of computer platforms.
>     Local Area Network (LAN)
>     A data network intended to serve an area of only a few square kilometers (or less). Because the network is known to cover only a small area, optimizations can be made in the network signal protocols that permit higher data rates. See also: Ethernet, fiber distributed data interface, token ring, Wide Area Network.
>     local loop
>     The local connection between the end user and the Class 5 central office.
>     logical
>     Without reference to physical details. Asking for data in a logical manner, for example, means not having to know where the data is located or how to get it.
>     logical link control
>     The upper portion of the data link layer, defined in the IEEE 802.2 standard. The logical link control layer presents a uniform interface to the user of the data link service, usually a network layer.
>     login
>     To gain access to a computer or network by identifying the acceptable user name and passing the required authentication procedure(s).
>     loop back
>     A method of performing transmission tests on a circuit without requiring the assistance of personnel at the distant end.
>     loop signaling
>     Any of the three signaling methods which use the metallic loop formed by the trunk conductors and the terminating equipment bridges.

>     ## - M -

>     Back to Top
>     MA
>     Acronym for Multiple Access
>     MAC
>     (1) Acronym for Move, Add & Changes. (2) Acronym for Media Access Control.
>     MAC address
>     The "built-in" hardware address of a device connected to shared media. It is determined by the Media Access Control (MAC) layer of OSI and by the network layer in TCP/IP. See also: Media Access Control, Ethernet, token ring, FDDI.
>     MAC-layer bridge
>     A device that connects two or more similar networks in a way that is transparent to the users of the network layer.
>     Magnetic Stripe Reader
>     A device that reads information recorded on the magnetic stripe of a card.
>     MAN
>     Acronym for Metropolitan Area Network.
>     Management Information Base (MIB)
>     The set of parameters an SNMP management station can query or set in the SNMP agent of a networked device (e.g., router). See also: client-server model, Simple Network Management Protocol.
>     mathematically infeasible
>     Something that is theoretically possible but technically impossible to accomplish in a timely manner is often called "mathematically infeasible".
>     MAU
>     Acronym for Multistation Access Unit (token ring) or medium attachment unit (Ethernet).
>     Mb
>     Acronym for megabit. Million bits of information (usually used to express a data transfer rate, like 1 megabit per second = 1Mbps).
>     MB
>     Acronym for megabyte. Million bytes of information.
>     Mbps
>     Acronym for million bits per second.
>     Mbyte
>     Acronym for megabyte. Million bytes of information.
>     Mean Time Between Failure (MTBF)
>     Average length of time for which the system, or component of the system, works without fault.
>     Mean Time To Failure (MTTF)
>     The average time until hardware breaks down or experiences a loss of service. This may be a calculation based on the reliability of component parts or an experience-based measurement.
>     Mean Time To Recovery (MTTR)
>     The average time it takes to restore service after a breakdown or loss. This is usually a measurement based on experience.
>     media
>     The plural of medium.
>     Media Access Control (MAC)
>     The lower portion of the datalink layer. The MAC differs for various physical media. See also: Ethernet, Logical Link Control, token ring.
>     Media Access Control (MAC)
>     The lower sublayer of the data link layer, which defines how computers on a LAN share access to a transmission medium, used in Carrier Sense Multiple Access with Collision Detection (CSMA/CD) and token ring LANs. The lowest sublayer of the IEEE's link layer (OSI).
>     media interface
>     The optical fiber connector which connects the fiber to the FDDI controllers.
>     medium
>     (1) Any substance that can be used for the propagation of signals, such as optical fiber, cable, wire, dielectric slab, water, air, or free space. (2) The material on which data is recorded; for example, magnetic type, diskette.
>     Medium Attachment Unit (MAU)
>     The device that attaches to an Ethernet/802.3 medium to transmit and receive signals; more often called a transceiver.
>     mega
>     A prefix meaning one million; for example, a megabit is one million bits and megahertz is one million hertz.
>     Megabyte (MB)
>     The name implies one million bytes of information, but it is actually 1,048,576 bytes.
>     Merchant Account
>     A bank account that can accept credit card payments and is required for automatic transaction of e-commerce payments.
>     Meta refresh tags
>     Web pages that automatically refresh, or move the user to another page within a Web site when visited.
>     Meta tags
>     Special tags hidden in the HTML source code of your Web site that provide information such as who created the page, how often it is updated, what the page is about, and which keywords represent the page's content.
>     Meta tags
>     A special HTML tag that provides information about a Web page. Unlike normal HTML tags, meta tags do not affect how the page is displayed. Instead, they provide information such as who created the page, how often it is updated, what the page is about, and which keywords represent the page's content. Many search engines use this information when building their indexes.
>     MFT
>     MultiFlex Trunk
>     MIB
>     Acronym for Management Information Base.
>     microcomputer
>     A small-scale programmable machine that processes information. It generally has a single chip as its central processing unit and includes storage and input/output facilities in the basic unit.
>     MIME
>     Multipurpose Internet Mail Extension.
>     MIS
>     Acronym for Management Information System.
>     MODEM
>     Acronym for MOdulation/DEModulator. It is a device which modulates and demodulates signals. It provides an interface between digital terminals and analog circuits and equipment.
>     modulation
>     Alterations in the characteristics of signals. Usually made to the amplitude and/or the frequency of the signal.
>     monitor bit
>     A token ring concept, in which the monitor bit is flipped by the active monitor to prevent a frame of priority greater than 0 from circulating continuously.
>     mouse
>     A hand-held input device, separate from a keyboard, that is moved on a surface to control the position of an indicator (cursor) on a display screen.
>     MTBF
>     Acronym for Mean-Time-Between-Failure.
>     MTTF
>     Acronym for Mean Time to Failure.
>     MTTR
>     Acronym for Mean Time to Recovery.
>     MTU
>     Acronym for Maximum Transmission Unit.
>     multi-access
>     The capability that allows multiple users to simultaneously communicate with a computer or a network.
>     multicast
>     A special form of broadcast in which copies of the packet are delivered to only a subset of all possible destinations that share a common multicast address. LAT nodes send their current status to each other using a multicast address. See also: broadcast.
>     multipoint
>     A network concept in which multiple nodes share a common physical medium. In this situation, each node must wait for a poll by the controller of the line before it can send data. Contrast with multi-access.
>     multipoint line
>     A single communications line to which more than one terminal is attached; also called multidrop.
>     multiport repeater
>     An Ethernet repeater that connects multiple segments together into a single logical Ethernet; also known as a hub or wiring concentrator.
>     multiport transceiver
>     Several Ethernet transceivers built into one device. The device can work as a concentrator or as a stand-alone Ethernet; also called "Ethernet in a Can".
>     multiprocessing
>     Simultaneous application processing on more than one processor in a multi-CPU computer system. This is possible only if the job can be defined as a number of separately executable tasks. Multi-processing is not multitasking, no matter what anyone tells you. Multi-tasking uses one CPU and runs more than one program at a time.

>     ## - N -

>     Back to Top
>     name registration scheme
>     The Name Resolution Scheme is the U.K. equivalent to the Domain Name System
>     name resolution
>     The process of mapping a name into its corresponding protocol address. See also: Domain Name System.
>     name server
>     (1) Host Name Server Protocol. Obsolete Internet protocol. (2) The device where all or part of the name service resides.
>     name service
>     The software system that provides a database of authorized users for a computer, subnet or network. It may reside on one device or be distributed over several devices in a network.
>     NCP
>     Acronym for NetWare Core Protocol or Network Control Protocol.
>     NetBEUI
>     Acronym for NetBIOS Enhanced User Interface.
>     NetBIOS
>     Acronym for Network Basic Input/Output System.
>     NetBIOS Enhanced User Interface (NetBEUI)
>     (Pronounced Net-Boo-ee) The NetBIOS transport layer protocol frequently used by LAN Manager and LAN Server. NetBEUI implements the OSI LLC2 protocol and communicates to the network adapter via the Network Driver Interface Specification (NDIS).
>     Netiquette
>     Contraction of Internet etiquette, the etiquette guidelines for posting messages to online services, particularly Internet newsgroups. Netiquette covers not only rules to maintain civility in discussions, but also special guidelines unique to the electronic nature of forum messages. For example, netiquette advises users to use simple formats because complex formatting may not appear correctly for all readers. In most cases, netiquette is enforced by fellow users who will vociferously object if a rule is broken.
>     Netiquette
>     Internet etiquette.
>     Netizen
>     A citizen of the internet.
>     NetWare
>     The major network operating system sold by Novell. A collection of data link drivers, a transport protocol stack, workstation software, and the NetWare operating system.
>     NetWare Core Protocols
>     Protocols used to obtain the core services offered by a NetWare file server. It includes a variety of facilities, such as file access, locking, printing, and job management.
>     NetWare Loadable Module (NLM)
>     Applications and drivers that can be loaded into a server, running the NetWare network operating system on the fly.
>     network
>     A computer network is a data communications system which interconnects computer systems at various different sites. A network may include any combination of LANs, MANs or WANs. See also: Local Area Network, Wide Area Network, Internet.
>     network address
>     (1) In TCP/IP, the network portion of an IP address. For a class A network, the network address is the first byte of the IP address. For a class B network, the network address is the first two bytes of the IP address. For a class C network, the network address is the first three bytes of the IP address. In each case, the remainder is the host address. In the Internet, assigned network addresses are globally unique. See also: Internet, IP address, subnet address, host address. (2) In NetWare, the unique number assigned to each logical node or network.
>     network application support
>     DEC standard to allow everything to work with everything else. Similar in scope and effectiveness to IBM's SAA.
>     network basic input/output system (NetBIOS)
>     A network session layer protocol that lets a client program find a server process and communicate with it. Similar to, but less powerful than, Named Pipes. See also: NetBIOS Enhanced User Interface.
>     Network Driver Interface Specification (NDIS)
>     A Microsoft specification for writing hardware-independent drivers at the data link (media access) layer.
>     Network File System (NFS)
>     A protocol, developed by Sun Microsystems, that allows a program running on one computer to use data stored on a different computer on the same Internet, as though it were on its local disks. It has been incorporated into hundreds of products and is a de facto Internet standard.
>     Network File Transfer
>     A procedure that lets a network user 1) copy a remote file, 2) translate file attributes, and 3) access remote accounts, either interactively or through a program.
>     Network Information Center(NIC)
>     A NIC provides information, assistance and services to network users. "The NIC" refers to the DDN NIC. See also: Network Operations Center.
>     Network Information Services (NIS)
>     A set of services, usually provided by a NIC, to help users use the network. See also: Network Information Center.
>     network layer
>     The OSI layer (layer 3) that is responsible for routing, switching, and subnetwork access across the entire OSI environment.
>     network management station
>     The system responsible for managing a network or a portion of a network. The NMS talks to network management agents, which reside in the managed nodes.
>     Network Management System (NMS)
>     Software for managing SNMP resources from a management workstation.
>     network meltdown
>     A state of complete network overload. The network equivalent of gridlock. See also: broadcast storm.
>     network number
>     The part of an Internet address which designates the network to which the addressed node belongs. See also: network address.
>     Network Operating System (NOS)
>     The software that manages the relationships between network resources and users. While there are several parts and protocols in an NOS, it is usually available as a single product.
>     Network Operations Center (NOC)
>     The site for monitoring the operation of and directing the management and maintenance of a network. See also: Network Information Center.
>     network time protocol (NTP)
>     A protocol to maintain accurate local timekeeping by using atomic clocks located on the Internet. It can synchronize distributed clocks within milliseconds over long time periods.
>     network trunks
>     Circuits that connect switching centers. See also: Network, Domain Name System, Network Information Center.
>     Nexus
>     Used for the determination of state taxation. A company is said to have ?nexus? in a state if it has a substantial physical presence in that state.
>     NFS
>     Acronym for Network File System.
>     NFT
>     Acronym for Network File Transfer.
>     nibble
>     Half of a byte; four bits.
>     NIC
>     Acronym for Network Information Center.
>     NIS
>     Acronym for Network Information Services.
>     NIST
>     Acronym for National Institute of Standards and Technology.
>     NLP
>     (1) Acronym for Network Layer Protocol. (2) Acronym for Neuro-Linguistic Programming.
>     NMS
>     Acronym for Network Management System.
>     NNTP
>     Network News Transfer Protocol. The protocol used for exchanging news postings on the Usenet
>     NOC
>     Acronym for Network Operations Center.
>     node
>     An addressable device attached to a computer network. See also: host, router, server.
>     non-blocking
>     A switching network having a sufficient number of paths so that a subscriber originating a call can always reach any other idle subscriber without encountering a busy state.
>     NOS
>     Acronym for Network Operating System.
>     Novell
>     The company that owns NetWare software for network communications and management. Currently, Novell is the dominant company in Local Area Networking.
>     Novell DOS
>     Previously called DR-DOS, it is a competitor to Microsoft's MS-DOS.
>     NPDU
>     Acronym for Network Protocol Data Unit.
>     NPID
>     Acronym for Network Layer Protocol Identifier. Used in the ES-IS protocols in the OSI network layer.
>     NSP
>     Acronym for Network Services Protocol.
>     NTP
>     Acronym for Network Time Protocol.

>     ## - O -

>     Back to Top
>     O/R address
>     Abbreviation for Originator/Recipient Address. A valid X.400 address.
>     OA
>     Acronym for Office Automation.
>     OA&M
>     Operations Administration and Maintenance: A group of network management functions that provide network fault idication, performance information, and data and diagnosis functions.
>     object
>     (1) In an office suite, an object can be a unit of information, like a picture or a table. (2) In software coding, an object is also a unit of information, a button, a table, a form letter or so forth can are all objects.
>     Object-Oriented Programming (OOP)
>     A programming model that is similar to real world function. It is modeled after the behaviors of little children - They see the object; they take some action; they get a result.
>     OC-12
>     an abbreviation for optical carrier level-12. A SONET channel of 622.08 Mbps.
>     occupancy
>     A telephone term defining the time a switch is in use.
>     OCLC
>     Acronym for Online Computer Library Catalog.
>     OCR
>     Acronym for Optical Character Recognition.
>     octal
>     Base 8. Often shortented to "oct". A numbering system using numerals 0 through 7. Decimal, or base 10 is the common numbering system used by people in everyday life. Computers internally use base 2 (binary), base 8 (octal) or base 16 (hexadecimal) and only convert numbers to base 10 for human consumption.
>     - decimal 8 = 10 octal
>     - decimal 10 = 12 octal
>     - decimal 64 = 100 octal
>       octet
>       A data communications term defining an eight-bit term. Unlike a byte that defines the word length for a machine which can vary (8,16,32,64...), an octet is a finite number of bits (8).
>       odd parity
>       A method of checking whether data has become corrupt in the transmission channel. In this parity scheme, all one bits are added; if the number is odd, the parity bit is not set. If the result is even, then the parity bit is set to make the result odd.
>       OEIC
>       Acronym for OptoElectronic Integrated Circuit.
>       OEM
>       Acronym for Original Equipment Manufacturer.
>       off hook
>       The condition that results when a hookswitch operates (closes) to provide access to the circuit.
>       off network
>       calling Calls through a private network which extend into a public network system.
>       Off Network Access Line (ONAL)
>       Usually a circuit leased by a remote service provider to offer access to the provider's network for service.
>       off-line
>       In network terms, "off-line" defines a device that is not in use.
>       off-line storage
>       Usually some type of tape data storage. Off-line storage is data that is not under the control of the processor.
>       ohm
>       A measurement of resistance.
>       Ohm?s law
>       The rules of the relationship of voltage, amperage, and resistance. Simply put, E (Voltage)=I (current) x R (resistance).
>       OIC
>       (1) An acronym for Online Informal Chat. (2) Slang for "Oh I see."
>       OID
>       Acronym for Object IDentifier in SNMP.
>       OIW OSI Implementers Workshop
>       A series of workshops hosted by the NIST.
>       OLTP
>       Acronym for On-Line Transaction Processing.
>       on hook
>       The condition that results when a hookswitch opens to halt access to the circuit.
>       on network calling
>       A call that originates and ends without leaving a private network.
>       on-line
>       Hardware or software in the current configuration or currently in use.
>       On-line Computer Library Catalog (OCLC)
>       A nonprofit membership-based organization that offers computer-based services to libraries, educational organizations, and their users. Its network connects more than 10,000 libraries worldwide.
>       on-line transaction processing
>       Any application that executes transactions interactively.
>       ONC
>       Acronym for Open Network Computing.
>       ONP
>       Acronym for Open Network Provision.
>       OOP
>       Acronym for Object-Oriented Programming.
>       opaque
>       A data type not interpreted by a program. Often used to store credentials for security applications or a file handle for NFS.
>       OPC
>       Acronym for Originating Point Code.
>       OPDU
>       Acronym for Operations Protocol Data Unit.
>       open
>       (1) A program, design, or specification, that can be used by anyone.(2) A circuit that is not complete; for example, the light will not turn on, because there is an "open" in the cable.
>       open air transmission
>       Any transmission that uses the air waves as the channel.
>       open DEConnect
>       The latest version of DEC's facility wiring system that is based on EIA standards.
>       open network architecture
>       Network architecture that is compatible with standards, thus allowing other systems to interface with the network without problems. The Federal Communications Commission has specified open network architecture and encourages all service providers to comply with these standards.
>       open network computing
>       A distributed applications architecture. Also, the Sun family of protocols that include the Network File System.
>       open protocol
>       A protocol that can be used by anyone.
>       Open Shortest Path First (OSPF)
>       An interior gateway protocol to replace RIP. Original acronym was OSPFIGP.
>       Open Software Foundation (OSF)
>       A nonprofit organization founded to develop specifications for an open software environment.
>       Open Systems Interconnection (OSI)
>       The seven-layer suite of protocols, designed by ISO committees to be the international standard computer network architecture. See also: International Organization for Standardization, OSI Reference Model.
>       open-ended access
>       A term defining the free access coverage area for phone service. A user has open-ended access for all "local" calls.
>       operating system
>       The personality or the heart and soul of a computer. Common operating systems are UNIX, Linux, DOS, Windows, and MAC.
>       optic-electrical transducer
>       Any device that changes light energy to/from electrical energy.
>       optic-electronics
>       Electronic devices that interface between light and electrical signals.
>       optical amplifier
>       An electronic device used to boost optical signals.
>       Optical Character Recognition (OCR)
>       A process that scans images, detects character shape matches, and converts them into digital code for the matching character.
>       optical disk
>       Also known as CD-ROM. A storage medium that used infrared light waves or laser technology to write and read to disk. They feature greater storage capacity than magnetic disks, but currently offer slower access.
>       optical waveguide
>       The term wave was first used for radio frequencies. A wave guide was tuned for ¼ wave length, providing a channel or guide for the radio frequencies to follow. Radio Wave guides are large and usually ridged structures. Optical wave guides are smaller, because the frequency is much higher thus the wave length is smaller. See also: Fiber Optic Cable.
>       Original Equipment Manufacturer (OEM)
>       A company that sells equipment that is included in another company's products. The integrating company may only put their name on the product and add marketing value.
>       OROM
>       Acronym for Optical Read-Only Memory.
>       OS
>       Acronym for Operating System.
>       OS/2
>       Acronym for Operating System/2. Graphical successor to DOS for the IBM PC. It was developed jointly by Microsoft and IBM, but now it is sold only by IBM.
>       oscillator
>       An electronic device used to generate frequencies. Used to operate the basic clock of computers; also test equipment.
>       oscilloscope
>       Test equipment that is used to display frequencies on a X-Y axis.
>       OSDIT
>       Acronym for Office of Software Development and Information Technology.
>       OSF
>       Acronym for Open Software Foundation.
>       OSI
>       Acronym for Open Systems Interconnection.
>       OSI network address
>       The address, consisting of up to 20 octets, that is used to locate an OSI transport layer entity. It contains an initial domain part and a domain specific part.
>       OSI presentation address
>       The address used to locate an OSI application layer entity. It includes an OSI network address and selector(s) used in the transport, session, and presentation layers.
>       OSI protocol stack
>       A seven-layer protocol stack specified by the International Standards Organization. The OSI stack is similar to the SNA stack. The seven layers are 1) Physical, 2) Data Link, 3) Network layer, 4) Transport, 5) Session, 6) Presentation and 7) Application.
>       OSI reference model
>       A seven-layer structure designed to describe computer network architectures and the way that data passes through them.
>       OSI standards
>       Standards established by the International Standards Organization called Open Systems Interconnection (OSI). The OSI standards define layers of operations in which each layer that operates is useful only on a network that does not lose or damage data independently of the other layers.
>       OSI transport protocol class 0
>       This is the simplest OSI transport protocol; this is the OSI equivalent to UDP.
>       OSI transport protocol class 4
>       This is the most powerful OSI transport protocol; it is useful on top of any type of network due to its error detection and recovery abilities. TP4 is the OSI equivalent to TCP.
>       OSINET
>       Acronym for the OSI NETwork sponsored by the National Bureau of Standards, (now NIST), for vendors using the OSI model.
>       OSME
>       Acronym for Open Systems Message Exchange
>       OSPF
>       Acronym for Open Shortest Path First.
>       OU
>       Acronym for Organization Unit. An X.400 address attribute indicating a subunit of an organization.
>       out-of-band
>       Any frequency separate from the band being used for data, voice, or video traffic. Typically requires a completely separate signal path or wire. Contrast with in-band.
>       out-of-band network management
>       Network management that does not use network carrier resources for monitoring. For example, routers could be controlled using LAN/WAN connections for in-band network management; however, if they are managed over the phone lines, they would be controlled out-of-band. The major advantages of this type of management: (1)bandwidth utilization; and, (2) the equipment can be serviced regardless of the condition of the network.
>       out-of-band signaling
>       Signaling, usually management or control, that is carried outside the primary data, voice or video band.
>       out-of-service
>       Equipment that is not in service. Equipment could be in maintenance move, failed, or out-of-service for any reason.
>       outernet
>       All online services that have Internet services, but do not have full connections.
>       outgoing connection timer
>       A session-layer control term. As the session layer issues a connect request to the transport layer, it starts this timer. If an accept or reject indication is not received before the timer expires, session control disconnects and informs the end user.
>       outgoing WATS
>       A dedicated telephone trunk for Wide-Area Telephone Service (WATS); it is used for outgoing calls only at a reduced or WATS rate.
>       outsourcing
>       When a company goes outside their organization for products or services. Outsourcing has become a major issue for labor unions and management in the 1990s. Unions claim that it reduces the opportunities for career growth of their members.
>       overbuild
>       To add extra capacity, wiring or radio, to a communications network.
>       overdrive processor
>       Vendor term for an added processor which increases the speed of the system.
>       overflow
>       (1) To exceed allocated space. (2)The data that exceeds the buffer's capacity for storage.
>       overflow traffic
>       The traffic that is above the processing capability of the switch; for example, in a system designed to process 200 calls per minute during peak busy minute, the volume of calls exceeding 200 calls per minute is overflow traffic.
>       overload control
>       In network management, a scheme to handle calls when the volume of traffic exceeds the maximum volume of calls; for example, a system may be designed to process 200 calls per minute during peak busy minute. If the volume exceeds 200 calls, the overload control will use a predefined routine to process the excess calls.

>       ## - P -

>       Back to Top
>       packet switch
>       A device to accept, route, and forward packets in a packet-switched network. See also: packet switching, router.
>       packet switched network
>       A network designed to carry data in the form of packets. The packet and its format are internal to that network.
>       packet switching
>       A communications paradigm in which packets (messages) are individually routed between hosts, with no previously established communication path. Like voice switching packet, switching paths may vary from call to call; unlike voice switching, packet switching can operate in the non-real time mode.
>       PAP
>       Password Authentication Protocol. PAP uses a two-step handshake. First, the client passes the username and password to the server, then the server sends an "accept" or "reject" back to the client. After a PPP link is established between client and server, PAP passes an unencrypted username and password across the link. This makes PAP vulnerable to attacks from someone eavesdropping on your link.
>       parity
>       Having a constant state or equal value. Parity checking is one of the oldest error checking techniques. In data communications, parity is a process of checking the integrity of the transmission by using additional bits. Simple parity checks such as odd or even parity add a parity place holder for every message. In the case of odd parity, if the data stream is even, the odd bit is set to one to make the data stream odd. If the stream is already odd, the bit is set to 0 or not set to keep the data stream odd.
>       parity bit
>       A check-bit appended to an array of binary digits for parity checking.
>       parity check
>       Addition of non-information bits to data, making the number of ones in each grouping of bits either always odd for odd parity or always even for even parity.
>       path
>       (1) A trail from point A to point B; for example, "To go to the store, follow the path behind the complex. It will lead you through the woods to the store." (2) In computer terms, a path takes a program from point A to point B. In DOS, a path is how a user finds a file on the disk drive; for example, to find a word file called "test.txt" one may have a path of: C:/access/word/data/test.txt (3) In data storage, the set of folders or subdirectories in which a file is stored. (4) In networking, the route, a series of data links, or hops that a packet takes from the source to the destination.
>       PBX
>       Acronym for Private Branch eXchange. A telephone switch which is installed on the customer premises.
>       PC
>       Acronym for Personal Computer.
>       PC-DOS
>       Acronym for Personal Computer Disk Operating System. IBM's version of Microsoft's MS-DOS operating system.
>       PC-NFS
>       Personal Computer Network File System.
>       PDC
>       NT Primary Domain Controller
>       Perl (Practical Extraction and Report Language)
>       A programming language designed for processing text, which has become one of the most popular languages for writing CGI scripts.
>       Permanent Virtual Circuit (PVC)
>       A circuit, as in X.25, that is kept up permanently, like a dedicated-leased line on the telephone network.
>       Personal identification number (PIN)
>       A 4-to-12 character secret code that allows an issuer to positively authenticate the cardholder for the purpose of approving an ATM or terminal transaction occurring at a point-of-interaction device.
>       physical layer
>       The OSI layer (layer 1) specification that defines signal voltages, encoding schemes, and physical connections for sending bits across a physical media.
>       physical media
>       Any means in the physical world for transferring signals between systems. Since it is outside (below) the OSI model, it is also known as "Layer 0". It includes all copper media, fiber optic media and wireless technologies.
>       PING
>       Acronym for Packet InterNet Groper. Used to test connectivity and data reliability across networks.
>       pipe
>       Typed as a vertical bar ( | ), this character and following indicators tell a process to move the output in a particular manner, typically as input to a follow-on process.
>       PMD
>       Physical Media Dependant
>       PNNI
>       Private Network-Network Interface: A routing information protocol that enables extrememly scalable, full-function, dynamic multi-vendor ATM switches to be integrated in the same network.
>       point to point
>       A network configuration that has a connection between only two terminal installations, as opposed to multipoint.
>       Point-to-Point Protocol (PPP)
>       A protocol for transmitting packets over serial, synchronous, and asynchronous point-to-point circuits. See also: Serial Line IP.
>       pointer
>       A DNS-resource record type used to provide an alias mechanism between one name and another.
>       Pop-up menus
>       Often used in dialog boxes to provide a list of mutually exclusive choices; a more compact choice than listing the items as radio buttons. Pop-up menus are indicated in both the Mac and Windows interfaces by rectangles with downward-pointing arrows.
>       port
>       Physically, an access point to a computer, multiplexer device or network. Logically, a pointer to a TCP/IP application.
>       Portals
>       Web sites that provide a single point of access, like a virtual front door, to aggregated information or product purchasing.
>       POTS
>       Acronym for Plain Old Telephone Service.
>       PPP
>       Acronym for Point-to-Point Protocol.
>       PQ
>       Priority Queuing
>       presentation address
>       OSI Presentation Layer Address.
>       presentation layer
>       The OSI layer (layer 6) that sets the way application information is coded to send it between two end systems.
>       PRI
>       Acronym for Primary Rate Interface.
>       Private Key
>       One of a key pair used in RSA cryptography. The Private Key is not distributed. It can decrypt data encrypted with its paired Public Key.
>       process
>       (1) verb, To perform one or more operations on information. (2) noun, An operation performed on data or information.
>       process identification
>       A number to identify each process running on an operating system.
>       processor
>       A computer or chip capable of receiving information, manipulating it, and supplying results.
>       prompting
>       Messages from a computer that give instructions to the user.
>       propagation delay
>       The one-way delay for the time it takes a signal to travel from one place to another.
>       propagation velocity
>       The speed that a signal travels through a medium from source to target. Also called Velocity of Propagation.
>       protocol
>       A formal description of message formats and the rules computers must follow to exchange those messages.
>       protocol analyzer
>       Specialized test equipment used to look at the details of traffic on a network. A protocol analyzer can be used to isolate network problems, as well as get around security procedures. Use this test equipment with care.
>       protocol conversion
>       The process of translating one protocol into another to offer communications compatibility.
>       protocol data unit (PDU)
>       An OSI term for "packet." A PDU is a data object exchanged by protocol machines (entities) within a given layer. In TCP/IP, it defines the type of SNMP message being sent.
>       protocol ID
>       The next-level (up) user of a service.
>       protocol stack
>       A modular set of functions, one at each layer of the stack, that forms a network service. Each layer of the stack uses the services of the module beneath it.
>       proxy
>       The process in which one system acts for another system to answer protocol requests.
>       proxy agent
>       An agent that queries on behalf of the manager, used to monitor objects that are not directly manageable.
>       proxy ARP
>       The process in which one device, usually a router, answers ARP requests intended for another device. By answering the ARP, the router accepts responsibility for routing packets to the "real" destination.
>       proxy server
>       A network device that can change network addresses. On the Internet side of a proxy server, the Internet Addresses are used, but on the user side, the addresses are different. Proxy servers are used to provide some level of security by acting as a type of firewall, so to speak. Proxy servers are also useful when one wants to change Internet service providers and does not want to change internal IP addresses.
>       PSTN
>       Acronym for Public Switched Telephone Network.
>       Public Data Network (PDN)
>       A network designed primarily for data transmission and intended for sharing by many users from many organizations.
>       Public Domain (PD)
>       Intellectual property that is freely available to all people.
>       Public Key
>       One of a key pair used in RSA cryptography. The Public Key is disclosed and widely distributed. It works only in conjunction with its paired Private Key.
>       public switched network
>       A telephone/data network that is used by the public. Unlike FTS and FTS-200, a public switched network is designed for private use.
>       Public Switched Telephone Network (PSTN)
>       The voice network that offers nationwide, unrestricted telephone service.
>       Pull-down menus
>       Menus that drop down from other menus allowing users to initiate some action directly.
>       PVC
>       Acronym for Permanent Virtual Circuit.

>       ## - Q -

>       Back to Top
>       Q.SAAL
>       Q. Signaling ATM Adaptation Layer - An ATM Adaptation Layer defined for the handling of signaling frames.
>       queue
>       (1) A backup of packets awaiting processing; (2) To stand in line; for example, the print job is third in the queue.
>       queuing
>       The act of putting objects in a line or a queue In a telephone switch, calls are queued according to the order in which they arrive and their priority. Computers and print servers also use queuing to determine the priority of items waiting to be served.

>       ## - R -

>       Back to Top
>       RAM
>       Acronym for Random Access Memory.
>       Random Access Memory (RAM)
>       Dynamic memory, sometimes known as main or core memory.
>       RARP
>       Reverse Address Resolution Protocol (RARP) is a protocol by which a physical machine in a local area network can learn its IP address from a gateway server's Address Resolution Protocol (ARP) table or cache.
>       Read The Flaming Manual (RTFM)
>       The response to a simple or common question.
>       redundancy
>       (1) The portion of the total information contained in a message that can be eliminated without loss of essential information. (2) Providing duplicate devices to immediately take over the function of equipment that fails.
>       remote access
>       The ability of network nodes or remote computers to gain access to a computer which is at a different location.
>       remote boot
>       The process used by a diskless node to load its operating system from a server. See also: Boot, BOOTP.
>       remote data access
>       An international standard for access to databases in a mixed-vendor data network.
>       repeater
>       An electronic device used to regenerate, at full strength, signals that have become too weak. It is used with digital signals and ignores illegal voltages, such as noise.
>       Request To Send (RTS)
>       A modem-control signal on a standard RS-232-C connector that puts the modem in originate mode so it can start to send data.
>       residual risk
>       Residual risks are the acceptable risks that exist after all reasonable countermeasures have been applied against a threat
>       response time
>       The amount of time elapsed between a generation of an inquiry at a system and receipt of a response at that same system.
>       RFC
>       Acronym for Request For Comments.
>       RGB
>       (1) Red, green, blue. A method of representing colors as a mix of the three primary colors. (2) A term that identifies a monitor designed to work with the PC Color Graphics Adapter (CGA).
>       RIP
>       Routing Information Protocol is an older routing protocol that routers use to broadcast routing tables based on a timer (every 30 seconds). It uses a distance vector algorithm and a single metric of hop counts to determine the best path selection.

>       The hops only measure how many routers are required to be passed through to get to a final destination (network). RIP version 1 is limited to 15 hops maximum.
>       RISC
>       Acronym for Reduced Instruction Set Computer.
>       RJ
>       Acronym for Registered Jack.
>       RJ11
>       A standard six conductor modular jack or plug that uses two to six conductors. Commonly used for telephones and some data communications.
>       RJ45
>       A standard eight-conductor modular jack or plug that uses two to eight conductors. Replacing RJ11 for use with data communications and increasing use with telephones. The wire may be twisted or flat, though flat will only work up to 19.2 Kbps.
>       Robot
>       A program that runs automatically without human intervention. Typically, a robot is endowed with artificial intelligence so that it can react to different situations it may encounter. Two common types of robots are agents and spiders.
>       ROM
>       Acronym for Read-Only Memory
>       route
>       (1) noun, The path that network traffic follows from its source host to its target host. (2) verb, To send a packet or frame of data through a network to its correct destination. In other words, what routers do.
>       route daemon
>       A program which runs under Berkeley and related UNIX systems to provide routes among hosts on a network, using RIP. See also: Routing Information Protocol.
>       routed
>       See Route Daemon. Pronounced "route d".
>       routed protocol
>       A protocol that can be routed by a router.
>       router
>       A device that forwards traffic between networks or subnetworks. It operates at the OSI Network Layer (layer 3) or the IP layer in TCP/IP.
>       routing
>       The process of selecting the correct interface and next hop for a packet being forwarded. See also: hop, router, Exterior Gateway Protocol, Interior Gateway Protocol.
>       routing code
>       A sequence of digits or characters that is required by the switching systems in order to route a transmission to its proper destination.
>       routing domain
>       A set of routers exchanging routing information within an administrative domain. See also: Administrative Domain, router.
>       routing domain number
>       A portion of an OSI address that is assigned by the Internet Assigned Numbers Authority.
>       routing flexibility
>       The ability of a router to route a transmission over various network paths to avoid congestion and use portions of another network that might otherwise be idle.
>       Routing Information Protocol (RIP)
>       An Interior Gateway Protocol supplied with UNIX and most routers. As "routed" (pronounced route-dee), it was developed for the Berkeley UNIX (BSD) operating system. It lets a group of hosts, located on a local network, to share routing information. RIP is used on many LANs; also called local routing process.
>       routing table
>       A network layer directory, in each router and some other computers in a network, that contains the addresses of other networks or devices and how to reach them.
>       Routing Table Maintenance Protocol (RTMP)
>       AppleTalk protocol for the maintenance of routing tables.
>       RS232-C
>       An EIA physical interface standard for use between Data Communications Equipment (DCE) and Data Terminal Equipment (DTE). The current standard is RS-232-E.
>       RS449
>       An EIA standard for the physical interface between Data Communications Equipment (DCE) and Data Terminal Equipment (DTE). It typically uses 37 pin connectors and twisted pair cabling.
>       RSA
>       Refers to a public-key encryption technology developed by RSA (Rivest, Shamir, and Adelman) Data Security, Inc. based on the fact that there is no efficient way to factor very large numbers.
>       RSVP
>       Resource reSerVation Protocol: Considered the most complex and least scaleable strategy for prioritizing voice packet's in a router's buffer.
>       RTCP
>       Real-Time Transport Control Protocol
>       RTFM
>       Acronym for Read The Flaming Manual.
>       rx
>       Abbreviation for receive.

>       ## - S -

>       Back to Top
>       S/Key
>       Cisco's S/Key [pronounced S Key] uses a hash to mask the actual text version of a password. With S/Key, remote logins can be sent over a non-secure network without much worry of someone eavesdropping. If a hacker captures the hash of a password, that password is automatically invalidated
>       safeguard
>       A safeguard, or countermeasure, is anything that lessens the threat a vulnerability presents
>       SAP
>       Service Access Point or Service Advisement Protocol.

>       The SAP is a conceptual location at which one OSI layer can request the services of another OSI layer.
>       script kiddies
>       Novice hackers that cause trouble with scripts and programs written by others, often without understanding the consequences of their actions.
>       SCSI
>       See Small Computer Systems Interface; pronounced "scuzz-ee".
>       Search engines
>       Database-driven indexes for Internet addresses. Search engines are how visitors will find your site, much like a phone book listing helps shoppers find a brick-and-mortar establishment.
>       Search spiders
>       A program that automatically retrieves Web pages. Spiders are used to feed pages to search engines. It's called a spider because it crawls over the Web. Another term for a search spider is webcrawler.
>       Secure Sockets Layer (SSL)
>       A protocol using a Private Key to encrypt data for transmitting private documents via the Internet.
>       sequence number
>       A unique number for every packet on a particular connection, maintained by a reliable transport layer service. The sequence number lets the transport layer know if any packets were lost or delivered out of sequence by the lower network layers.
>       serial
>       A transmission method that sends each bit of data sequentially on a single channel; also called serial transmission.
>       Serial Line Internet Protocol (SLIP)
>       A protocol that lets a normal computer use Internet protocols and turn itself into an Internet site via phone lines. See also: PPP.
>       server
>       A computing device on a network that shares its resources with the other computers on the network. This device can be anything from a brawny PC to a mainframe computer. There are many different types of servers; for example, a file server stores application programs or data files, while a print server enables computers on a network to print from a shared printer(s).
>       service access point
>       The point that the services of a network layer are made available to the next higher layer.
>       Service Advertisement Protocol (SAP)
>       The NetWare protocol for publicizing the current network address of available services.
>       session
>       A networking term used to refer to the logical stream of data flowing between two programs that are communicating over a network.
>       session layer
>       The OSI layer (layer 5) that offers dialogue control between end systems.
>       SGML
>       Standard Generalized Markup Language
>       Shareware
>       Software available on the Internet that is usually free as long as users following certain stipulations.
>       Shielded Twisted Pair (STP)
>       Two, or more, insulated wires that are twisted together and then wrapped in a cable with metallic braid or foil to prevent interference and offer noise-free transmissions. Also refers to IBM Type 1 cable.
>       SIC
>       The Standard for Internet Commerce is an organization aimed at garnering high levels of customer satisfaction, service, security, and privacy, as well as increasing e-merchant innovations and profitability.
>       Signature file
>       Signature files, or sig files, are footers you can set your email software to automatically generate at the bottom of every message you send.
>       SIMM
>       Acronym for Single In-line Memory Module.
>       Simple Mail Transfer Protocol (SMTP)
>       The Internet electronic mail protocol used to transfer electronic mail between hosts. See also: electronic mail, RFC 822.
>       Simple Network Management Protocol (SNMP)
>       The Internet standard protocol for managing nodes on an IP network. See also: Management Information Base.
>       SNMP
>       Simple Network Management Protocol. Commonly used in Unix networks.
>       socket
>       A TCP/IP port number and an IP address form a socket.
>       Spam
>       Unsolicited, bulk or mass emails that are considered bad netiquette and can result in loss of service.
>       Spam
>       Electronic junk mail or junk newsgroup postings. Some people define spam even more generally as any unsolicited email. If a long-lost brother finds your email address and sends you a message, however, this could hardly be called spam, even though it's unsolicited. Real spam is generally e-mail advertising for some product sent to a mailing list or newsgroup.
>       Spiders
>       Special information gathering programs used by search engines for indexing Web sites. These programs are also called "robots", "bots" or "crawlers".
>       Spoofing
>       Occurs when a company's server accepts and uses incorrect information from a host that has no authority giving that information.
>       SSCF
>       Service Specific Coordination Function: BISDN support function for support of sinaling at the UNI interface.
>       SSCOP
>       Service Specific Connection Oriented Protocol: A means to provide a reliable transport of signaling frames across a UNI interface.
>       stacking
>       In programming, a special type of data structure in which items are removed in the reverse order from that in which they are added, so the most recently added item is the first one removed. This is also called last-in, first-out (LIFO).
>       Static HTML
>       Short for HyperText Markup Language, it is the authoring language used to create documents on the World Wide Web. HTML is similar to SGML, although it is not a strict subset.
>       Stemming
>       Practiced by search engines of searching for variations of a word based on its stem.
>       stop bit
>       The bit that terminates the character frame; a marker to ensure that a start bit will be clearly recognized on the mark-to-space transition.
>       Stop words
>       Small words like a, an, the, he, she, it that some search engines ignore as a way to save storage space or to speed searches.
>       store and forward
>       The process of message handling in message-switching systems in which the message is temporarily stored before being forwarded to its final destination.
>       stub network
>       A stub network only carries packets to and from local hosts.
>       subnet
>       A portion of a network that shares a network address with other subnets, but it is distinguished by a unique subnet number. A subnet is to a network as a network is to an internet.
>       subnet address
>       The network-significant part of the locally administered portion of a network IP address. It can be identified by using a subnet (or address) mask. See also: address mask, IP address, network address, host address.
>       subnet mask
>       See address mask.
>       subnet number
>       A part of the Internet address which designates a subnet. It is ignored for the purposes of Internet routing, but is used for intranet routing and management.
>       subnetwork
>       A group of OSI end systems and intermediate systems under the control of a single administrative domain and using a common network access protocol.
>       SubNetwork Access Protocol (SNAP)
>       A version of the IEEE local area network logical link control frame, that lets a user use nonstandard higher-level protocols.
>       Subscription web site
>       Driven by providing a small amount of free but timely information, software, or online services to which consumers pay a fee to subscribe.
>       Surf
>       To go from one place to another on the Internet.
>       Switched Multimegabit Data Service (SMDS)
>       A high-speed, datagram-based, public data network service developed by Bellcore and expected to be widely used by telephone companies in their data networks.
>       switching
>       The operations required to interconnect circuits and establish communications.
>       switching center
>       A site where the traffic is switched or connected from one physical circuit or line to another in order to complete the communications link.

>       ## - T -

>       Back to Top
>       T1
>       A digital carrier facility for transmitting a single DS1 digital stream over two pairs of regular copper telephone wires at 1.544 Mbps. It has come to mean any 1.544 Mbps digital stream, regardless of what transmission medium.
>       T3
>       A digital carrier facility used to transmit a DS3 digital stream at 44.746 Mbps. It has come to mean any 44.746 Mbps digital stream, regardless of what transmission medium.
>       TCP
>       See Transmission Control Protocol.
>       TCP/IP Protocol Suite
>       Transmission Control Protocol over Internet Protocol. This is a common shorthand which refers to the suite of transport and application protocols which run over IP. See also IP, ICMP, TCP, UDP, FTP, Telnet, SMTP, SNMP, TFTP.
>       telco
>       Acronym for local telephone company.
>       Telnet
>       The virtual terminal protocol in the Internet suite of protocols. It lets users on one host access another host and work as terminal users of that remote host.
>       terminal
>       A device that lets a user interactively communicate with a network or computer.
>       Terminal Access Point (TAP)
>       A point at which information can enter or leave a communications network.
>       terminal emulator
>       A program that lets a computer emulate a terminal. The workstation looks like a terminal to the host.
>       terminal equipment
>       Devices and their interfaces used to send information to a user or remote host.
>       terminal server
>       A device that connects many terminals (and similar devices) to a LAN through one network connection. See also: Local Area Network.
>       termination
>       Connecting an impedance device (such as a resistor) to the end of a circuit to prevent signal reflections or echoes.
>       text
>       A sequence of characters that forms the part of a transmission that is sent from one application to another over a network.
>       TFTP
>       Acronym for Trivial File Transfer Protocol.
>       three-way-handshake
>       A process that two protocol entities use to synchronize while setting up a connection.
>       Time To Live (TTL)
>       A field in the IP header which indicates how long a packet should be allowed to survive before being discarded.
>       TN
>       A shortened form of the Telnet command.
>       token ring
>       A network access method and topology in which a token is passed from station to station in sequential order. Stations wishing to send data must wait for the token before transmitting data. In a token ring, the next logical station is also the next physical station on the ring.
>       transceiver
>       See Transmitter-Receiver or medium attachment unit.
>       transfer protocols
>       Any protocol that uses packets; data is put into a packet that contains information about the sending and receiving addresses, routing information, and the data. Transfer protocols were designed for the efficient transferring of large data files.
>       transit network
>       A network that passes traffic between networks and carries traffic for its own hosts. It must have paths to at least two other networks. See also: backbone, stub network.
>       transmission
>       The electrical transfer of a signal, message, or other form of data from one location to another.
>       Transmission Control Protocol (TCP)
>       An Internet standard transport protocol in the Internet protocols suite for reliable, connection-oriented, and full-duplex streams. Contrast with User Datagram Protocol.
>       Transmission Control Protocol/Internet Protocol (TCP/IP)
>       A set of protocols developed by the Department of Defense's Advanced Research Projects Agency (DARPA), to link dissimilar computers across many different types of networks. TCP/IP is the protocol that the Internet runs on, and is basically the glue that holds it together. Without TCP/IP, the Internet would be almost impossible, because without it everyone would have to have the same network running on the same protocols on the same computers. This allows people to keep their networks the way they like them, and still be able to have world-wide data communications. TCP/IP is still a stack protocol suite like Open System Interconnection (OSI), but it only has four layers, instead of seven.
>       transmission speed
>       The number of bits transmitted in a given period of time, usually expressed as bits per second (bps).
>       transmitter-receiver
>       The physical device that connects a system interface to a network, such as Ethernet. Ethernet transceivers have electronics that apply signals to the cable and sense collisions. It is the same as a medium attachment unit.
>       transparent mode
>       Transmission of binary data with the recognition of most control characters suppressed. In binary synchronous communications, entry to and exit from the transparent mode is indicated by set sequences.
>       transport layer
>       The OSI layer (layer 4) responsible for reliable end-to-end data transfer between two end systems.
>       Trivial File Transfer Protocol (TFTP)
>       A simpler, less-reliable form of File Transfer Protocol (FTP) that does not provide password protection or a user-directory capability. TFTP is less reliable because it uses User Datagram Protocol (UDP), a connectionless datagram delivery service.
>       Trojan Horse
>       A destructive program that masquerades as a benign application but instead gives your system?s private information to someone else.
>       TTL
>       Acronym for Time To Live.
>       tunneling
>       Carrying protocol A packets within protocol B packets so that B treats A as though it were a higher level protocol. It is used to get data between network segments that use a protocol that is not supported by the Internet. See also: encapsulation.
>       twisted pair
>       A type of cable in which pairs of conductors are twisted together to produce certain electrical properties. See also: shielded twisted pair, unshielded twisted pair.
>       two-wire circuit
>       Circuit formed by two conductors insulated from each other, that can be used as a one-way transmission path, half-duplex path, or duplex path.
>       tx
>       Abbreviation for "transmit".

>       ## - U -

>       Back to Top
>       UART
>       Acronym for Universal Asynchronous Receiver Transmitter. (Pronounced "U-art").
>       UBR
>       Unspecified Bit Rate: A best effort quality of service category.
>       UDP
>       User Datagram Protocol: a connectionless datagram delivery service.

>       Applications that do not require data acknowledgments, or ones that provide these functions, can successfully use UDP services.
>       UI
>       Acronym for Unnumbered Information.
>       ULP
>       Upper Layer Protocol. (See IOS)
>       UN/EDIFACT
>       Abbreviation for The United Nations/Electronic Data Interchange for Administration, Commerce, and Transport. It is an international standard for the facilitation of trade goods and services.
>       UNI
>       User-Network Interface: An interface point between ATM end users and a private ATM switch, or between a private ATM switch and the public carrier ATM network.
>       Uninterruptible Power Supply (UPS)
>       A device that provides continuous power in case the main power source fails. It includes filtering that provides extremely "well-behaved" AC power signal.
>       UNIX
>       An early computer operating system that is arguably the root of all modern operating systems. UNIX was developed in 1969 by Ken Thompson of AT&T Bell Laboratories. There are several types of UNIX operating systems called shells. UNIX provides multi-tasking, multi-user capabilities, and remains a contender in the modern operating system market.
>       Unix
>       A popular multi-user, multitasking operating system developed at Bell Laboratories in the early 1970s.
>       Unshielded Twisted Pair (UTP)
>       Cable that consists of two or more insulated conductors, in which each pair of conductors are twisted around each other. There is no external protection, and noise resistance comes solely from the twists. See also: Category Cable.
>       UPS
>       See Uninterruptible Power Supply. (Pronounced u-p-s).
>       URI
>       Uniform Resource Identifier. It may appear as a location (URL) or a name (URN).
>       URL
>       Uniform Resource Locator. A web address, e.g. "http://www.mindfire.com"

>       ## - V -

>       Back to Top
>       VBR
>       Variable Bit Rate: A quality of service designed to support packetized, variable bit rate, video and voice.
>       VBR-nRT
>       Variable Bit Rate for non-Real Time (traffic)
>       VBR-RT
>       Variable Bit Rate for Real Time (traffic)
>       VC
>       Acronym for Virtual Call.
>       VCC
>       Virtual Channel Connection: An established virtual connection across the ATM network.
>       virtual circuit
>       A network service that lets two processes communicate as though they were directly connected without regard for the structure of the underlying network.
>       virus
>       A program that replicates itself, usually to the detriment of the system, by incorporating itself into other programs which are shared among computer systems.
>       VLSM
>       Variable Length Subnet Masks (VLSMs) provide more efficient use of IP address space by using host potions of IP addresses to define subnets.

>       255.255.255.0 is a normal subnet mask

>       255.255.255.192 is a VLSM that allows the breakup of the 254 host IDs into 2 subnets.
>       VoFR
>       Voice over Frame Relay
>       Voice over Frame Relay
>       Using Frame Relay technology to transmit digital voice data
>       Voice over Internet Protocol
>       Digital voice data transmitted over IP
>       VoIP
>       Voice over Internet Protocol
>       VPI/VCI
>       Virtual Path Identifier/Virtual Channel Identifier: Connection Identifiers used to ensure that cells follow the correct Virtual Circuit across the ATM network.
>       VPN
>       A Virtual Private Network (VPN) allows private communications over a public network. This is usually accomplished via some kind of tunneling protocol and in many cases involves encryption.
>       vulnerability
>       In computer security terms: A vulnerability is anything that allows a threat to be made

>       ## - W -

>       Back to Top
>       WAIS
>       Wide Area Information Server. Indexes document contents. It is a program that searches a certain body of texts for certain words
>       WAN
>       See Wide Area Network.
>       Web Browser
>       Software used by computers that allows users to access information on the World Wide Web.
>       Web Server
>       A dedicated computer that delivers interactive text, graphics, digital audio or video over the World Wide Web to Web browser programs.
>       Well Known Port
>       The first 1,024 TCP/IP port addresses (zero through 1,023) and are reserved for specific applications. A port number and an IP address form a socket.
>       well-known address method
>       The standardized ATM End Station Address that is assigned to the LECS.
>       WFQ
>       Weighted Fair Queueing: Considered the simplest strategy for prioritizing voice packets in a router?s buffer.
>       Wide Area Network (WAN)
>       A network that covers a large geographic area. See also: Local Area Network, Metropolitan Area Network.
>       window
>       (1) The advertised buffer space available to receive data in TCP. (2) The mechanism used for flow control in a packet-switched network to prevent overload in the network.
>       Window styles
>       All interfaces provide a number of standard window styles. Window styles also incorporate standard interface elements such as scroll bars, close boxes, pop-up menus, and "zoom boxes."
>       workstation
>       A networked computing device with additional processing power and RAM. Often, a workstation runs an operating system, such as UNIX or Windows or Apple's System 7, so that several tasks can run simultaneously.
>       World Wide Web (WWW)
>       A project that merges information retrieval and hypertext to make an easy to use, powerful, global, academic information system.
>       World Wide Web (WWW)
>       A set of standards originally conceived at the Particle Physics Lab in Switzerland in 1990 which allow all Internet-connected computers to easily communicate with each other through a mouse-based point and click interface.
>       worm
>       A computer program that replicates and distributes itself. Worms, as opposed to viruses, are meant to spread in network environments. The November 1988 Internet worm, that entered thousands of Internet systems, is the most famous.

>       ## - X -

>       Back to Top
>       X windows
>       X is the name for TCP/IP-based, network-oriented window systems. Network window systems let a program use a display on a different computer. The most widely-implemented window system is X11 - a component of MIT's Project Athena.
>       XML
>       Extensible Markup Language

>       ## - Y -

>       Back to Top

>       ## - Z -

>       Back to Top

>       ## - # -

>       Back to Top
>       100Base-VG
>       A joint AT&T-HP proposal for a 100 Mbps, four-pair, category 3 Ethernet. It is being standardized by the IEEE 802.12 working group.
>       100Base-X
>       A Grand Junction Networks proposal for 100 Mbps Ethernet using 2 pairs of category 5 wire and CSMA/CD. It is being standardized by the IEEE 802.13 working group.
>       10Base2 10 Mbps, baseband, in185-meter segments
>       The IEEE 802.3 substandard for ThinWire, coaxial, Ethernet.
>       10Base5 10 Mbps, baseband, in 500-meter segments
>       The IEEE 802.3 substandard for ThickWire, coaxial, Ethernet.
>       10BaseF 10 Mbps, baseband, over fiber-optic cabling
>       The IEEE 802.3 substandard for fiber optic, Ethernet.
>       10BaseT 10 Mbps, baseband, over twisted pair
>       The IEEE 802.3 substandard for unshielded twisted pair, Ethernet.
>       802.2
>       IEEE standard for the Logical Link Control.
>       802.3
>       IEEE standard for CSMA/CD (Ethernet) medium access method.
>       802.5
>       IEEE standard for the token ring medium access method.
>       802.x
>       The set of IEEE standards for the definition of LAN protocols.

>       #### Click here to return to the title