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Versions: 00                                                            
Internet Draft                  Glossary                   February 2001

draft-ietf-uswg-glossary-00.txt              Gary Malkin/Nortel Networks
                                                           February 2001

                        Internet Users' Glossary

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet- Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at

   The list of Internet-Draft Shadow Directories can be accessed at


   There are many networking glossaries in existence.  This glossary
   concentrates on terms which are specific to the Internet.  Naturally,
   there are entries for some basic terms and acronyms because other
   entries refer to them.


   This document is the work of the User Services Working Group of the
   User Services Area of the Internet Engineering Task Force.

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Table of Contents

non-letter  . .  3      I . . . . . . . 26      R . . . . . . . 46
A . . . . . . .  3      J . . . . . . . 33      S . . . . . . . 49
B . . . . . . .  8      K . . . . . . . 33      T . . . . . . . 52
C . . . . . . . 11      L . . . . . . . 33      U . . . . . . . 55
D . . . . . . . 15      M . . . . . . . 35      V . . . . . . . 57
E . . . . . . . 18      N . . . . . . . 39      W . . . . . . . 57
F . . . . . . . 20      O . . . . . . . 43      X . . . . . . . 59
G . . . . . . . 23      P . . . . . . . 43      Y . . . . . . . 60
H . . . . . . . 24      Q . . . . . . . 46      Z . . . . . . . 60

References  . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Security Considerations . . . . . . . . . . . . . . . . . . . . 62
Editors' Addresses  . . . . . . . . . . . . . . . . . . . . . . 62

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   A physical layer communications specification for 10Mbps, baseband
   data transmission over a coaxial cable (Thinnet) with a maximum cable
   segment length of 200 meters.

   A physical layer communications specification for 10Mbps, baseband
   data transmission over a coaxial cable (Thicknet) with a maximum
   cable segment length of 500 meters.

   A physical layer communications specification for 10Mbps, baseband
   data transmission over a fiber-optic cable.

   A physical layer communications specification for 10Mbps, baseband
   data transmission over a twisted-pair copper wire.

   The set of IEEE standards for the definition of LAN protocols.  See
   also: IEEE.

   See: RFC 822

   This odd symbol is one of the ways a person can portray "mood" in the
   very flat medium of computers--by using "smiley faces".  This is
   "metacommunication", and there are literally hundreds of such
   symbols, from the obvious to the obscure.  This particular example
   expresses "happiness".  Don't see it?  Tilt your head to the left 90
   degrees.  Smiles are also used to denote sarcasm.
   [Source: ZEN]

abstract syntax
   A description of a data structure that is independent of machine-
   oriented structures and encodings.
   [Source: RFC1208]

Abstract Syntax Notation One (ASN.1)
   The language used by the OSI protocols for describing abstract
   syntax.  This language is also used to encode SNMP packets.  ASN.1 is
   defined in ISO documents 8824.2 and 8825.2.  See also: Basic Encoding

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Acceptable Use Policy (AUP)
   Many transit networks have policies which restrict the use to which
   the network may be put.  For example, some networks may only be used
   for non-commercial purposes.  Some AUPs limit the type of material
   which can be made available to the public (e.g., pornographic
   material).  Enforcement of AUPs varies with the network.  See also:

Access Control List (ACL)
   Most network security systems operate by allowing selective use of
   services.  An Access Control List is the usual means by which access
   to, and denial of, services is controlled.  It is simply a list of
   the services available, each with a list of the hosts permitted to
   use the service.

   See: Acknowledgment

acknowledgment (ACK)
   A type of message sent to indicate that a block of data arrived at
   its destination without error.  See also: Negative Acknowledgement.
   [Source: NNSC]

   See: Access Control List

   See: Administrative Domain

   There are four types of addresses in common use within the Internet.
   They are email address; IP, internet or Internet address; hardware or
   MAC address; and URL.  See also: email address, IP address, internet
   address, MAC address, Uniform Resource Locator.

address mask
   A bit mask used to identify which bits in an IP address correspond to
   the network and subnet portions of the address.  This mask is often
   referred to as the subnet mask because the network portion of the
   address (i.e., the network mask) can be determined by the encoding
   inherent in an IP address.  See also: Classless Inter-domain Routing.

address resolution
   Conversion of a network-layer address (e.g. IP address) into the
   corresponding physical address (e.g., MAC address).  See also: IP
   address, MAC address.

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Address Resolution Protocol (ARP)
   Used to dynamically discover the low level physical network hardware
   address that corresponds to the high level IP 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.  See
   also: proxy ARP, Reverse Address Resolution Protocol.

Administrative Domain (AD)
   A collection of hosts and routers, and the interconnecting
   network(s), managed by a single administrative authority.

Advanced Research Projects Agency (ARPA)
   An agency of the U.S. Department of Defense responsible for the
   development of new technology for use by the military.  ARPA
   (formerly known as DARPA, nee ARPA) was responsible for funding much
   of the development of the Internet we know today, including the
   Berkeley version of Unix and TCP/IP.
   [Source: NNSC]

Advanced Research Projects Agency Network (ARPANET)
   A pioneering longhaul network funded by ARPA.  Now retired, it served
   as the basis for early networking research as well as a central
   backbone during the development of the Internet.  The ARPANET
   consisted of individual packet switching computers interconnected by
   leased lines.  See also: Advanced Research Projects Agency.
   [Source: FYI4]

   In the client-server model, the part of the system that performs
   information preparation and exchange on behalf of a client or server
   [Source: RFC1208]

   A name, usually short and easy to remember, that is translated into
   another name, usually long and difficult to remember.

American National Standards Institute (ANSI)
   This organization is responsible for approving U.S. standards in many
   areas, including computers and communications.  Standards approved by
   this organization are often called ANSI standards (e.g., ANSI C is
   the version of the C language approved by ANSI).  ANSI is a member of
   ISO.  See also: International Organization for Standardization.
   [Source: NNSC]

American Standard Code for Information Interchange (ASCII)
   A standard character-to-number encoding widely used in the computer
   industry.  See also: EBCDIC.

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anonymous FTP
   Anonymous FTP allows a user to retrieve documents, files, programs,
   and other archived data from anywhere in the Internet without having
   to establish a userid and password.  By using the special userid of
   "anonymous" the network user will bypass local security checks and
   will have access to publicly accessible files on the remote system.
   See also: archive site, File Transfer Protocol, World Wide Web.

   See: American National Standards Institute

   See: Application Program Interface

   A networking protocol developed by Apple Computer for communication
   between Apple Computer products and other computers.  This protocol
   is independent of the network layer on which it is run.  Current
   implementations exist for Localtalk, a 235Kb/s local area network;
   and Ethertalk, a 10Mb/s local area network.
   [Source: NNSC]

   A program that performs a function directly for a user.  FTP, mail
   and Telnet clients are examples of network applications.

application layer
   The top layer of the network protocol stack.  The application layer
   is concerned with the semantics of work (e.g. formatting electronic
   mail messages).  How to represent that data and how to reach the
   foreign node are issues for lower layers of the network.
   [Source: MALAMUD]

Application Program Interface (API)
   A set of calling conventions which define how a service is invoked
   through a software package.
   [Source: RFC1208]

   A system to automatically gather, index and serve information on the
   Internet.  The initial implementation of archie provided an indexed
   directory of filenames from all anonymous FTP archives on the
   Internet.  Later versions provide other collections of information.
   See also: archive site, Gopher, Prospero, Wide Area Information

archive site
   A machine that provides access to a collection of files across the

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   Internet.  For example, an anonymous FTP archive site provides access
   to arcived material via the FTP protocol.  WWW servers can also serve
   as archive sites.  See also: anonymous FTP, archie, Gopher, Prospero,
   Wide Area Information Servers, World Wide Web.

   See: Address Resolution Protocol

   See: Advanced Research Projects Agency

   See: Advanced Research Projects Agency Network

   See: Autonomous System

   See: American Standard Code for Information Interchange

   See: Abstract Syntax Notation One

assigned numbers
   The RFC [STD2] which documents the currently assigned values from
   several series of numbers used in network protocol implementations.
   This RFC is updated periodically and, in any case, current
   information can be obtained from the Internet Assigned Numbers
   Authority (IANA).  If you are developing a protocol or application
   that will require the use of a link, socket, port, protocol, etc.,
   please contact the IANA to receive a number assignment.  See also:
   Internet Assigned Numbers Authority, STD.
   [Source: STD2]

Asynchronous Transfer Mode (ATM)
   A standard which defines high-load, high-speed (1.544Mbps through
   1.2Gbps), fixed-size packet (cell) switching with dynamic bandwidth
   allocation.  ATM is also known as "fast packet."

   See: Asynchronous Transfer Mode

   See: Acceptable Use Policy

   The verification of the identity of a person or process.
   [Source: MALAMUD]

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Autonomous System (AS)
   A collection of routers under a single administrative authority using
   a common Interior Gateway Protocol for routing packets.

   The top level in a hierarchical network.  Stub and transit networks
   which connect to the same backbone are guaranteed to be
   interconnected.  See also: stub network, transit network.

   Technically, the difference, in Hertz (Hz), between the highest and
   lowest frequencies of a transmission channel.  However, as typically
   used, the amount of data that can be sent through a given
   communications circuit.

bang path
   A series of machine names used to direct electronic mail from one
   user to another, typically by specifying an explicit UUCP path
   through which the mail is to be routed.  See also: email address,
   mail path, UNIX-to-UNIX CoPy.

   A transmission medium through which digital signals are sent without
   complicated frequency shifting.  In general, only one communication
   channel is available at any given time.  Ethernet is an example of a
   baseband network.  See also: broadband, Ethernet.
   [Source: NNSC]

Basic Encoding Rules (BER)
   Standard rules for encoding data units described in ASN.1.  Sometimes
   incorrectly lumped under the term ASN.1, which properly refers only
   to the abstract syntax description language, not the encoding
   technique.  See also: Abstract Syntax Notation One.
   [Source: NNSC]

   See: Bulletin Board System

   Be Seein' You

   The newest subseries of RFCs which are written to describe Best
   Current Practices in the Internet.  Rather than specifying a
   protocol, these documents specify the best ways to use the protocols
   and the best ways to configure options to ensure interoperability
   between various vendors' products.  BCPs carry the endorsement of the
   IESG.  See also: Request For Comments, Internet Engineering Steering

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   See: Basic Encoding Rules

Berkeley Internet Name Daemon (BIND)
   Implementation of a DNS server developed and distributed by the
   University of California at Berkeley.  Many Internet hosts run BIND,
   and it is the ancestor of many commercial BIND implementations.  See
   also: Domain Name System.

Berkeley Software Distribution (BSD)
   Implementation of the UNIX operating system and its utilities
   developed and distributed by the University of California at
   Berkeley.  "BSD" is usually preceded by the version number of the
   distribution, e.g., "4.3 BSD" is version 4.3 of the Berkeley UNIX
   distribution.  Many Internet hosts run BSD software, and it is the
   ancestor of many commercial UNIX implementations.
   [Source: NNSC]

   See: Border Gateway Protocol

   A format for storage or transmission of binary data in which the most
   significant bit (or byte) comes first.  The term comes from
   "Gulliver's Travels" by Jonathan Swift.  The Lilliputians, being very
   small, had correspondingly small political problems.  The Big-Endian
   and Little-Endian parties debated over whether soft-boiled eggs
   should be opened at the big end or the little end.  See also: little-
   [Source: RFC1208]


   See: Berkeley Internet Name Daemon

Birds Of a Feather (BOF)
   A Birds Of a Feather (flocking together) is an informal discussion
   group.  It is formed, often ad hoc, to consider a specific issue and,
   therefore, has a narrow focus.  See also: Working Group.

   An academic computer network that provides interactive electronic
   mail and file transfer services, using a store-and-forward protocol,
   based on IBM Network Job Entry protocols.  Bitnet-II encapsulates the

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   Bitnet protocol within IP packets and depends on the Internet to
   route them.

   See: Birds Of a Feather

   The Bootstrap Protocol, described in RFC 1542, is used for booting
   diskless nodes.  See also: Dynamic Host Configuration Protocol,
   Reverse Address Resolution Protocol.

Border Gateway Protocol (BGP)
   The Border Gateway Protocol is an exterior gateway protocol defined
   in RFC 1771.  It's design is based on experience gained with EGP, as
   defined in RFC 904, and EGP usage in the NSFNET Backbone, as
   described in RFCs 1092 and 1093.  See also: Exterior Gateway

   The return of a piece of mail because of an error in its delivery.
   [Source: ZEN]

   A device which forwards traffic between network segments based on
   datalink layer information.  These segments would have a common
   network layer address.  See also: gateway, router.

   A transmission medium capable of supporting a wide range of
   frequencies.  It can carry multiple signals by dividing the total
   capacity of the medium into multiple, independent bandwidth channels,
   where each channel operates only on a specific range of frequencies.
   See also: baseband.

   A special type of multicast packet which all nodes on the network are
   always willing to receive.  See also: multicast, unicast.

broadcast storm
   An incorrect packet broadcast onto a network that causes multiple
   hosts to respond all at once, typically with equally incorrect
   packets which causes the storm to grow exponentially in severity.
   See also: Ethernet meltdown.

   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

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   configuration information.  See also: bridge, router.

   A software application that allows users to access the World Wide
   Web.  The first production browser was released by Netscape.

   See: Berkeley Software Distribution

   By The Way

Bulletin Board System (BBS)
   A computer, and associated software, which typically provides
   electronic messaging services, archives of files, and any other
   services or activities of interest to the bulletin board system's
   operator.  Although BBS's have traditionally been the domain of
   hobbyists, an increasing number of BBS's are connected directly to
   the Internet, and many BBS's are currently operated by government,
   educational, and research institutions.  See also: Electronic Mail,
   Internet, Usenet.
   [Source: NWNET]

cable modem
   A device that allows digital data to be sent and received over a CATV
   network.  A typical cable modem presents a 10baseT interface to the
   data network, and has a standard CATV connector.

Campus Wide Information System (CWIS)
   A CWIS makes information and services publicly available on campus
   via kiosks, and makes interactive computing available via kiosks,
   interactive computing systems and campus networks. Services routinely
   include directory information, calendars, bulletin boards, databases.

   See: Coordinating Committee for Intercontinental Research Networks

   See: Comite Consultatif International de Telegraphique et

   See: Computer Emergency Response Team

   A computed value which is dependent upon the contents of a packet.
   This value is sent along with the packet when it is transmitted.  The
   receiving system computes a new checksum based upon the received data

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   and compares this value with the one sent with the packet.  If the
   two values are the same, the receiver has a high degree of confidence
   that the data was received correctly.  See also: Cyclic Redundancy
   [Source: NNSC]

   See: Classless Inter-domain Routing

circuit switching
   A communications paradigm in which a dedicated communication path is
   established between two hosts, and on which all packets travel.  The
   telephone system is an example of a circuit switched network.  See
   also: connection-oriented, connectionless, packet switching.

Classless Inter-domain Routing (CIDR)
   A proposal, set forth in RFC 1519, to allocate IP addresses so as to
   allow the addresses to be aggregated when advertised as routes.  It
   is based on the elimination of intrinsic IP network addresses; that
   is, the determination of the network address based on the first few
   bits of the IP address.  See also: IP address, network address,

   A computer system or process that requests a service of another
   computer system or process.  A workstation requesting the contents of
   a file from a file server is a client of the file server.  See also:
   client-server model, server.
   [Source: NNSC]

client-server model
   A common way to describe the paradigm of many network protocols.
   Examples include the name-server/name-resolver relationship in DNS
   and the file-server/file-client relationship in NFS.  See also:
   client, server, Domain Name System, Network File System.

   See: Coalition for Networked Information

Coalition for Networked Information (CNI)
   A consortium formed by American Research Libraries, CAUSE, and EDUCOM
   (no, they are not acronyms) to promote the creation of, and access
   to, information resources in networked environments in order to
   enrich scholarship and enhance intellectual productivity.

Comite Consultatif International de Telegraphique et Telephonique (
   This organization is now part of the International Telecommunications

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   Union and is responsible for making technical recommendations about
   telephone and data communications systems.  Every four years CCITT
   holds plenary sessions where they adopt new standards; the most
   recent was in 1992.  Recently, the ITU reorganized and CCITT was
   renamed the ITU-TSS.  See also: International Telecommunications
   Union - Telecommunications Standards Sector.

Computer Emergency Response Team (CERT)
   The CERT was formed by ARPA in November 1988 in response to the needs
   exhibited during the Internet worm incident.  The CERT charter is to
   work with the Internet community to facilitate its response to
   computer security events involving Internet hosts, to take proactive
   steps to raise the community's awareness of computer security issues,
   and to conduct research targeted at improving the security of
   existing systems.  CERT products and services include 24-hour
   technical assistance for responding to computer security incidents,
   product vulnerability assistance, technical documents, and tutorials.
   In addition, the team maintains a number of mailing lists (including
   one for CERT Advisories), and provides an anonymous FTP server, at
   "cert.org", where security-related documents and tools are archived.
   The CERT may be reached by email at "cert@cert.org" and by telephone
   at +1-412-268-7090 (24-hour hotline).  See also: Advanced Research
   Projects Agency, worm.

   Congestion occurs when the offered load exceeds the capacity of a
   data communication path.

   The data communication method in which communication proceeds through
   three well-defined phases: connection establishment, data transfer,
   connection release.  TCP is a connection-oriented protocol.  See
   also: circuit switching, connectionless, packet switching,
   Transmission Control Protocol.

   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 is a
   connectionless protocol.  See also: circuit switching, connection-
   oriented, packet switching, User Datagram Protocol.

Coordinating Committee for Intercontinental Research Networks (CCIRN)
   A committee that includes the United States FNC and its counterparts
   in North America and Europe.  Co-chaired by the executive directors
   of the FNC and the European Association of Research Networks (RARE),
   the CCIRN provides a forum for cooperative planning among the
   principal North American and European research networking bodies.

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   See also: Federal Networking Council, RARE.
   [Source: MALAMUD]

core gateway
   Historically, one of a set of gateways (routers) operated by the
   Internet Network Operations Center at Bolt, Beranek and Newman (BBN).
   The core gateway system formed a central part of Internet routing in
   that all groups must advertise paths to their networks from a core
   [Source: MALAMUD]

Corporation for Research and Educational Networking (CREN)
   This organization was formed in October 1989, when Bitnet and CSNET
   (Computer + Science NETwork) were combined under one administrative
   authority.  CSNET is no longer operational, but CREN still runs
   Bitnet.  See also: Bitnet.
   [Source: NNSC]

   A cracker is an individual who attempts to access computer systems
   without authorization.  These individuals are often malicious, as
   opposed to hackers, and have many means at their disposal for
   breaking into a system.  See also: hacker, Computer Emergency
   Response Team, Trojan Horse, virus, worm.

   See: cyclic redundancy check

   See: Corporation for Research and Educational Networking

   Pronnounced "See you, See me," CU-SeeMe is a publicly available
   videoconferencing program developed at Cornell University.  It allows
   anyone with audio/video capabilites and an Internet connection to
   videoconference with anyone else with the same capabilities.  It also
   allows multiple people to tie into the same videoconference.

   See: Campus Wide Information system

   A term coined by William Gibson in his fantasy novel Neuromancer to
   describe the "world" of computers, and the society that gathers
   around them.
   [Source: ZEN]

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Cyclic Redundancy Check (CRC)
   A number derived from a set of 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 some types of
   transmission errors.  See also: checksum.
   [Source: MALAMUD]

   A non-profit company founded in July 1993 to help the European
   research community enhance their networking facilities.  It focuses
   on the establishment of a high-speed computer network infrastructure.

   Defense Advanced Research Projects Agency
   See: Advanced Research Projects Agency

Data Encryption Key (DEK)
   Used for the encryption of message text and for the computation of
   message integrity checks (signatures).  See also: encryption.

Data Encryption Standard (DES)
   A popular, standard encryption scheme.  See also: encryption, Pretty
   Good Privacy, RSA.

   A self-contained, independent entity of data carrying sufficient
   information to be routed from the source to the destination computer
   without reliance on earlier exchanges between this source and
   destination computer and the transporting network.  See also: frame,
   [Source: J. Postel]

   See: Defense Information Systems Agency

   Data Circuit-terminating Equipment

   See: Distributed Computing Environment

   See: Defense Data Network

   See: Defense Data Network Network Information Center

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   A proprietary network protocol designed by Digital Equipment
   Corporation.  The functionality of each Phase of the implementation,
   such as Phase IV and Phase V, is different.

default route
   A routing table entry which is used to direct packets addressed to
   networks not explicitly listed in the routing table.
   [Source: MALAMUD]

Defense Data Network (DDN)
   A global communications network serving the US Department of Defense
   composed of MILNET, other portions of the Internet, and classified
   networks which are not part of the Internet.  The DDN is used to
   connect military installations and is managed by the Defense
   Information Systems Agency.  See also: Defense Information Systems

Defense Data Network Network Information Center (DDN NIC)
   Previously called "The NIC", the DDN NIC's primary responsibility was
   the assignment of Internet network addresses and Autonomous System
   numbers, the administration of the root domain, and providing
   information and support services to the Internet for the DDN.  Since
   the creation of the InterNIC, the DDN NIC performs these functions
   only for the DDN.  See also: Autonomous System, network address,
   Internet Registry, InterNIC, Network Information Center, Request For

Defense Information Systems Agency (DISA)
   Formerly called the Defense Communications Agency (DCA), this is the
   government agency responsible for managing the DDN portion of the
   Internet, including the MILNET.  Currently, DISA administers the DDN,
   and supports the user assistance services of the DDN NIC.  See also:
   Defense Data Network.

   See: Data Encryption Key

   See: Data Encryption Standard

   A temporary, as opposed to dedicated, connection between machines
   established over a phone line (analog or ISDN).  See also: Integrated
   Services Digital Network.

Directory Access Protocol
   X.500 protocol used for communication between a Directory User Agent

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   and a Directory System Agent.
   [Source: MALAMUD]

Directory System Agent (DSA)
   The software that provides the X.500 Directory Service for a portion
   of the directory information base.  Generally, each DSA is
   responsible for the directory information for a single organization
   or organizational unit.
   [Source: RFC1208]

Directory User Agent (DUA)
   The software that accesses the X.500 Directory Service on behalf of
   the directory user.  The directory user may be a person or another
   software element.
   [Source: RFC1208]

   See: Defense Information Systems Agency

Distributed Computing Environment (DCE)
   An architecture of standard programming interfaces, conventions, and
   server functionalities (e.g., naming, distributed file system, remote
   procedure call) for distributing applications transparently across
   networks of heterogeneous computers.  Promoted and controlled by the
   Open Software Foundation (OSF), a consortium led by Digital, IBM and
   Hewlett Packard.
   [Source: RFC1208]

distributed database
   A collection of several different data repositories that looks like a
   single database to the user.  A prime example in the Internet is the
   Domain Name System.

DIX Ethernet
   See: Ethernet

   See: Domain Name System

   "Domain" is a heavily overused term in the Internet.  It can be used
   in the Administrative Domain context, or the Domain Name context.
   See also: Administrative Domain, Domain Name System.

Domain Name System (DNS)
   The DNS is a general purpose distributed, replicated, data query
   service.  The principal use is the lookup of host IP addresses based
   on host names.  The style of host names now used in the Internet is

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   called "domain name", because they are the style of names used to
   look up anything in the DNS.  Some important domains are: .COM
   (commercial), .EDU (educational), .NET (network operations), .GOV
   (U.S. government), and .MIL (U.S. military).  Most countries also
   have a domain.  The country domain names are based on ISO 3166.  For
   example, .US (United States), .UK (United Kingdom), .AU (Australia).
   See also: Fully Qualified Domain Name, Mail Exchange Record.

dot address (dotted decimal notation)
   Dot address refers to the common notation for IP addresses of the
   form A.B.C.D; where each letter represents, in decimal, one byte of a
   four byte IP address.  See also: IP address.
   [Source: FYI4]

   See: Directory System Agent

   Data Terminal Equipment

   See: Directory User Agent

dynamic adaptive routing
   Automatic rerouting of traffic based on a sensing and analysis of
   current actual network conditions.  NOTE: this does not include cases
   of routing decisions taken on predefined information.
   [Source: J. Postel]

   The basic building block for European multi-megabit data rates, with
   a bandwidth of 2.048Mbps.  See also: T1.

   A European standard for transmitting data at 57.344Mbps.  See also:

   European Academic and Research Network.  See: Trans-European Research
   and Education Networking Association.

   See: Extended Binary Coded Decimal Interchange Code

   A pan-European backbone service.

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   See: Electronic Frontier Foundation

   See: Exterior Gateway Protocol

Electronic Frontier Foundation (EFF)
   A foundation established to address social and legal issues arising
   from the impact on society of the increasingly pervasive use of
   computers as a means of communication and information distribution.

Electronic Mail (email)
   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]

   See: Electronic mail

email 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
   "gmalkin@xylogics.com".  See also: bang path, mail path, UNIX-to-UNIX
   [Source: ZEN]

   The technique used by layered protocols in which a layer adds header
   information to the protocol data unit (PDU) from the layer above.
   For example, in Internet terminology, a packet would contain a header
   from the physical layer, followed by a header from the datalink layer
   (e.g.  Ethernet), followed by a header from the network layer (IP),
   followed by a header from the transport layer (e.g. TCP), followed by
   the application protocol data.
   [Source: RFC1208]

   Encryption is the manipulation of a packet's data in order to prevent
   any but the intended recipient from reading that data.  There are
   many types of data encryption, and they are the basis of network
   security.  See also: Data Encryption Standard.

error checking
   The examination of received data for transmission errors.  See also:
   checksum, Cyclic Redundancy Check.

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   A 10-Mb/s standard for LANs, initially developed by Xerox, and later
   refined by Digital, Intel and Xerox (DIX).  All hosts are connected
   to a coaxial cable where they contend for network access using a
   Carrier Sense Multiple Access with Collision Detection (CSMA/CD)
   paradigm.  See also: 802.x, Local Area Network, token ring.

Ethernet meltdown
   An event that causes saturation, or near saturation, on an Ethernet.
   It usually results from illegal or misrouted packets and typically
   lasts only a short time.  See also: broadcast storm.
   [Source: COMER]

Extended Binary Coded Decimal Interchange Code (EBCDIC)
   A standard character-to-number encoding used primarily by IBM
   computer systems.  See also: ASCII.

Exterior Gateway Protocol (EGP)
   A protocol which distributes routing information to the routers which
   connect autonomous systems.  The term "gateway" is historical, as
   "router" is currently the preferred term.  There is also a routing
   protocol called EGP defined in RFC 904.  See also: Autonomous System,
   Border Gateway Protocol, Interior Gateway Protocol.

eXternal Data Representation (XDR)
   A standard for machine independent data structures developed by Sun
   Microsystems and defined in RFCs 1014 and 1832.  It is similar to
   ASN.1.  See also: Abstract Syntax Notation One.
   [Source: RFC1208]

   A non-profit corporation, established in 1987, whose mission is to
   advance the use of computer networks to improve research and

   Frequently Asked Question

   See: Fiber Distributed Data Interface

Federal Information Exchange (FIX)
   One of the connection points between the American governmental
   internets and the Internet.
   [Source: SURA]

Federal Networking Council (FNC)
   The coordinating group of representatives from those federal agencies

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   involved in the development and use of federal networking, especially
   those networks using TCP/IP and the Internet.  Current members
   include representatives from DOD, DOE, ARPA, NSF, NASA, and HHS.  See
   also: Advanced Research Projects Agency, National Science Foundation.

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
   ring.  See also: Local Area Network, token ring.
   [Source: RFC1208]

file transfer
   The copying of a file from one computer to another over a computer
   network.  See also: File Transfer Protocol, Kermit, Gopher, World
   Wide Web.

File Transfer Protocol (FTP)
   A protocol which allows a user on one host to access, and transfer
   files to and from, another host over a network.  Also, FTP is usually
   the name of the program the user invokes to execute the protocol.
   See also: anonymous FTP.

   A protocol, defined in RFC 1288, that allows information about a
   system or user on a system to be retrived.  Finger also refers to the
   commonly used program which retrieves this information.  Information
   about all logged in users, as well is information about specific
   users may be retrieved from local or remote systems.  Some sites
   consider finger to be a security risk and have either disabled it, or
   replaced it with a simple message.

   See: Federal Information Exchange

   A strong opinion and/or criticism of something, usually as a frank
   inflammatory statement, in an electronic mail message.  It is common
   to precede a flame with an indication of pending fire (i.e. FLAME
   ON!).  Flame Wars occur when people start flaming other people for
   flaming when they shouldn't have.  See also: Electronic Mail, Usenet.

   See: Four Letter Extended Acronym

   See: Federal Networking Council

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Four Letter Extended Acronym (FLEA)
   A recognition of the fact that there are far too many TLAs.  See
   also: Three Letter Acronym.

   See: Fully Qualified Domain Name

   A piece of a packet.  When a router is forwarding an IP packet to a
   network that has a maximum transmission unit smaller than the packet
   size, it is forced to break up that packet into multiple fragments.
   These fragments will be reassembled by the IP layer at the
   destination host.  See also: Maximum Transmission Unit.

   The IP process in which a packet is broken into smaller pieces to fit
   the requirements of a physical network over which the packet must
   pass.  See also: reassembly.

   A frame is a datalink layer "packet" which contains the header and
   trailer information required by the physical medium.  That is,
   network layer packets are encapsulated to become frames.  See also:
   datagram, encapsulation, packet.

   Community-based bulletin board system with email, information
   services, interactive communications, and conferencing.  Freenets are
   funded and operated by individuals and volunteers -- in one sense,
   like public television.  They are part of the National Public
   Telecomputing Network (NPTN), an organization based in Cleveland,
   Ohio, devoted to making computer telecommunication and networking
   services as freely available as public libraries.
   [Source: LAQUEY]

   See: File Transfer Protocol

Fully Qualified Domain Name (FQDN)
   The FQDN is the full name of a system, rather than just its hostname.
   For example, "venera" is a hostname and "venera.isi.edu" is an FQDN.
   See also: hostname, Domain Name System.

   For Your Information

   A subseries of RFCs that are not technical standards or descriptions

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   of protocols.  FYIs convey general information about topics related
   to TCP/IP or the Internet.  See also: Request For Comments.

   Gatedaemon.  A program which supports multiple routing protocols and
   protocol families.  It may be used for routing, and makes an
   effective platform for routing protocol research.  The software is
   freely available by anonymous FTP from "gated.cornell.edu".
   Pronounced "gate-dee".  See also: Exterior Gateway Protocol, Open
   Shortest-Path First, Routing Information Protocol, routed.

   The term "router" is now used in place of the original definition of
   "gateway".  Currently, a gateway is a communications device/program
   which passes data between networks having similar functions but
   dissimilar implementations.  This should not be confused with a
   protocol converter.  By this definition, a router is a layer 3
   (network layer) gateway, and a mail gateway is a layer 7 (application
   layer) gateway.  See also: mail gateway, router, protocol converter.

   A distributed information service, developed at the University of
   Minnesota, that makes hierarchical collections of information
   available across the Internet.  Gopher uses a simple protocol,
   defined in RFC 1436, that allows a single Gopher client to access
   information from any accessible Gopher server, providing the user
   with a single "Gopher space" of information.  Public domain versions
   of the client and server are available.  See also: archie, archive
   site, Prospero, Wide Area Information Servers.

   See: Government OSI Profile

Government OSI Profile (GOSIP)
   A subset of OSI standards specific to U.S. Government procurements,
   designed to maximize interoperability in areas where plain OSI
   standards are ambiguous or allow excessive options.

   A person who delights in having an intimate understanding of the
   internal workings of a system, computers and computer networks in
   particular.  The term is often misused in a pejorative context, where
   "cracker" would be the correct term.  See also: cracker.

   The portion of a packet, preceding the actual data, containing source
   and destination information. It may also error checking and other
   fields.  A header is also the part of an electronic mail message

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   which precedes the body of a message and contains, among other
   things, the message originator, date and time.  See also: Electronic
   Mail, packet, error checking.

heterogeneous network
   A network running multiple network layer protocols.  See also:
   DECnet, IP, IPX, XNS, homogeneous network.

hierarchical routing
   The complex problem of routing on large networks can be simplified by
   reducing the size of the networks.  This is accomplished by breaking
   a network into a hierarchy of networks, where each level is
   responsible for its own routing.  The Internet has, basically, three
   levels: the backbones, the mid-levels, and the stub networks.  The
   backbones know how to route between the mid-levels, the mid-levels
   know how to route between the sites, and each site (being an
   autonomous system) knows how to route internally.  See also:
   Autonomous System, Exterior Gateway Protocol, Interior Gateway
   Protocol, stub network, transit network.

High Performance Computing and Communications (HPCC)
   High performance computing encompasses advanced computing,
   communications, and information technologies, including scientific
   workstations, supercomputer systems, high speed networks, special
   purpose and experimental systems, the new generation of large scale
   parallel systems, and application and systems software with all
   components well integrated and linked over a high speed network.
   [Source: HPCC]

High Performance Parallel Interface (HIPPI)
   An emerging ANSI standard which extends the computer bus over fairly
   short distances at speeds of 800 and 1600 Mb/s.  HIPPI is often used
   in a computer room to connect a supercomputer to routers, frame
   buffers, mass-storage peripherals, and other computers.  See also:
   American National Standards Institute
   [Source: MALAMUD]

   See: High Performance Parallel Interface

   See: Hypertext Markup Language

homogeneous network
   A network running a single network layer protocol.  See also: DECnet,
   IP, IPX, XNS, heterogeneous network.

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   A term used in routing.  A path to a destination on a network is a
   series of hops, through routers, away from the origin.

   A computer that allows users to communicate with other host computers
   on a network.  Individual users communicate by using application
   programs, such as electronic mail, Telnet and FTP.
   [Source: NNSC]

host address
   See: internet address

   The name given to a machine.  See also: Fully Qualified Domain Name.
   [Source: ZEN]

host number
   See: host address

   See: High Performance Computing and Communications

   See: Hypertext Transfer Protocol

   See: Hypertext Transfer Protocol Secure

   A device connected to several other devices.  In ARCnet, a hub is
   used to connect several computers together.  In a message handling
   service, a hub is used for the transfer of messages across the
   [Source: MALAMUD]

   A pointer within a hypertext document which points (links) to another
   document, which may or may not also be a hypertext document.  See
   also: hypertext.

   A document, written in HTML, which contains hyperlinks to other
   documents, which may or may not also be hypertext documents.
   Hypertext documents are usually retrieved using WWW.  See also:
   hyperlink, Hypertext Markup Language, World Wide Web.

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Hypertext Markup Language (HTML)
   The language used to create hypertext documents.  It is a subset of
   SGML and includes the mechanisms to establish hyperlinks to other
   documents.  See also: hypertext, hyperlink, Standardized General
   Markup Language.

Hypertext Transfer Protocol (HTTP)
   The protocol used by WWW to transfer HTML files.  A formal standard
   is still under development in the IETF.  See also: hyperlink,
   hypertext, Hypertext Markup Language, World Wide Web.

Hypertext Transfer Protocol Secure (HTTPS)
   A secure (encrypted) version of HTTP.

   See: Internet-Draft

   See: Internet Architecture Board

   See: Internet Assigned Numbers Authority

   See: Internet Control Message Protocol

   Institute of Electrical and Electronics Engineers

IEEE 802
   See: 802.x

   See: Internet Experiment Note

   See: Internet Engineering Planning Group

   See: Internet Engineering Steering Group

   See: Internet Engineering Task Force

   See: Interior Gateway Protocol

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   In My Humble Opinion

   See: Internet Monthly Report

Integrated Services Digital Network (ISDN)
   An emerging technology which is beginning to be offered by the
   telephone carriers of the world.  ISDN combines voice and digital
   network services in a single medium, making it possible to offer
   customers digital data services as well as voice connections through
   a single "wire."  The standards that define ISDN are specified by
   CCITT.  See also: CCITT.
   [Source: RFC1208]

Interior Gateway Protocol (IGP)
   A protocol which distributes routing information to the routers
   within an autonomous system.  The term "gateway" is historical, as
   "router" is currently the preferred term.  See also: Autonomous
   System, Exterior Gateway Protocol, Open Shortest-Path First, Routing
   Information Protocol.

Intermediate System (IS)
   An OSI system which performs network layer forwarding.  It is
   analogous to an IP router.  See also: Open Systems Interconnection,

Intermediate System-Intermediate System (IS-IS)
   The OSI IGP.  See also: Open Systems Interconnection, Interior
   Gateway Protocol.

International Organization for Standardization (ISO)
   A voluntary, nontreaty organization founded in 1946 which is
   responsible for creating international standards in many areas,
   including computers and communications.  Its members are the national
   standards organizations of the 89 member countries, including ANSI
   for the U.S.  See also: American National Standards Institute, Open
   Systems Interconnection.
   [Source: TAN]

International Telecommunications Union (ITU)
   An agency of the United Nations which coordinates the various
   national telecommunications standards so that people in one country
   can communicate with people in another country.

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International Telecommunications Union -
        Telecommunications Standards Sector (ITU-TSS)
   The new name for CCITT since the ITU reorganization. The function is
   the same; only the name has been changed

   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.

   (note the capital "I") The Internet is the largest internet in the
   world.  Is a three level hierarchy composed of backbone networks
   (e.g. Ultranet), mid-level networks (e.g., NEARnet) and stub
   networks.  The Internet is a multiprotocol internet.  See also:
   backbone, mid-level network, stub network, transit network, Internet

internet address
   A IP address that uniquely identifies a node on an internet.  An
   Internet address (capital "I"), uniquely identifies a node on the
   Internet.  See also: internet, Internet, IP address.

Internet Architecture Board (IAB)

   The IAB has been many things over the years.  Originally the Internet
   Activities Board, it was responsible for the development of the
   protocols which make up the Internet.  It later changed its name and
   charter to become the group most responsible for the architecture of
   the Internet, leaving the protocol details to the IESG.  In June of
   1992, it was chartered as a component of the Internet Society; this
   is the charter it holds today.  The IAB is responsible for approving
   nominations to the IESG, architectural oversight for Internet
   Standard Protocols, IETF standards process oversight and appeals,
   IANA and RFC activities, and liaison to peer standards groups (e.g.,
   ISO).  See also: Internet Engineering Task Force, Internet Research
   Task Force, Internet Engineering Steering Group, Internet Assigned
   Numbers Authority, Request for Comments.

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.  The currently assigned values are listed in the "Assigned
   Numbers" document [STD2].  To request a number assignment, contact
   the IANA at "iana@isi.edu".  See also: assigned numbers, STD.

Internet Control Message Protocol (ICMP)
   ICMP is an extension to the Internet Protocol.  It allows for the

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   generation of error messages, test packets and informational messages
   related to IP.
   [Source: FYI4]

Internet-Draft (I-D)
   Internet-Drafts are working documents of the IETF, its Areas, and its
   Working Groups.   As the name implies, Internet-Drafts are draft
   documents.  They are valid for a maximum of six months and may be
   updated, replaced, or obsoleted by other documents at any time.  Very
   often, I-Ds are precursors to RFCs.  See also: Internet Engineering
   Task Force, Request For Comments.

Internet Engineering Planning Group (IEPG)
   A group, primarily composed of Internet service operators, whose goal
   is to promote a globally coordinated Internet operating environment.
   Membership is open to all.

Internet Engineering Steering Group (IESG)
   The IESG is composed of the IETF Area Directors and the IETF Chair.
   It provides the first technical review of Internet standards and is
   responsible for day-to-day "management" of the IETF.  See also:
   Internet Engineering Task Force.

Internet Engineering Task Force (IETF)
   The IETF is a large, open community of network designers, operators,
   vendors, and researchers whose purpose is to coordinate the
   operation, management and evolution of the Internet, and to resolve
   short-range and mid-range protocol and architectural issues.  It is a
   major source of proposals for protocol standards which are submitted
   to the IAB for final approval.  The IETF meets three times a year and
   extensive minutes are included in the IETF Proceedings.  See also:
   Internet, Internet Architecture Board.
   [Source: FYI4]

Internet Experiment Note (IEN)
   A series of reports pertinent to the Internet.  IENs were published
   in parallel to RFCs and were intended to be  "working documents."
   They have been replaced by Internet-Drafts and are currently of
   historic value only.  See also: Internet-Draft, Request For Comments.

Internet Monthly Report (IMR)
   Published monthly, the purpose of the Internet Monthly Reports is to
   communicate to the Internet Research Group the accomplishments,
   milestones reached, or problems discovered by the participating

internet number
   See: internet address

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Internet Protocol (IP, IPv4)
   The Internet Protocol (version 4), defined in RFC 791, is the network
   layer for the TCP/IP Protocol Suite.  It is a connectionless, best-
   effort packet switching protocol.  See also: packet switching, TCP/IP
   Protocol Suite, Internet Protocol Version 6.

Internet Protocol Version 6 (IPng, IPv6)
   IPv6 (version 5 is a stream protocol used for special applications)
   is a new version of the Internet Protocol which is designed to be an
   evolutionary step from its predecessor, version 4.  There are many
   RFCs defining various portions of the protocol, its auxiliary
   protocols, and the transition plan from IPv4.  The core RFCs are 1883
   through 1886.  The name IPng (IP next generation) is a nod to STNG
   (Star Trek Next Generation).

Internet Registry (IR)
   The IANA has the discretionary authority to delegate portions of its
   responsibility and, with respect to network address and Autonomous
   System identifiers, has lodged this responsibility with an IR.  The
   IR function is performed by the DDN NIC.  See also: Autonomous
   System, network address, Defense Data Network..., Internet Assigned
   Numbers Authority.

Internet Relay Chat (IRC)
   A world-wide "party line" protocol that allows one to converse with
   others in real time.  IRC is structured as a network of servers, each
   of which accepts connections from client programs, one per user.  See
   also: talk.
   [Source: HACKER]

Internet Research Steering Group (IRSG)
   The "governing body" of the IRTF.  See also: Internet Research Task
   [Source: MALAMUD]

Internet Research Task Force (IRTF)
   The IRTF is chartered by the IAB to consider long-term Internet
   issues from a theoretical point of view.  It has Research Groups,
   similar to IETF Working Groups, which are each tasked to discuss
   different research topics.  Multi-cast audio/video conferencing and
   privacy enhanced mail are samples of IRTF output.  See also: Internet
   Architecture Board, Internet Engineering Task Force, Privacy Enhanced

Internet Society (ISOC)
   The Internet Society is a non-profit, professional membership
   organization which facilitates and supports the technical evolution
   of the Internet, stimulates interest in and educates the scientific

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   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.  The Society provides
   a forum for discussion and collaboration in the operation and use of
   the global Internet infrastructure.  The Internet Society publishes a
   quarterly newsletter, the Internet Society News, and holds an annual
   conference, INET.  The development of Internet technical standards
   takes place under the auspices of the Internet Society with
   substantial support from the Corporation for National Research
   Initiatives under a cooperative agreement with the US Federal
   [Source: V. Cerf]

Internetwork Packet eXchange (IPX)
   Novell's protocol used by Netware.  A router with IPX routing can
   interconnect LANs so that Novell Netware clients and servers can
   communicate.  See also: Local Area Network.

   A five year project, partially supported by the National Science
   Foundation, to provide network information services to the networking
   community.  The InterNIC began operations in April of 1993 and is now
   a collaborative project of two organizations: AT&T, which provides
   Directory and Database Services from South Plainsfield, NJ; and
   Network Solutions, Inc., which provides Registration Services from
   their headquarters in Herndon, VA.  Services are provided via the
   Internet, and by telephone, FAX, and hardcopy.

   The ability of software and hardware on multiple machines from
   multiple vendors to communicate meaningfully.

IP (IPv4)
   See: Internet Protocol

IPng (IPv6)
   See: Internet Protocol Version 6

IP address
   The 32-bit address defined by the Internet Protocol in RFC 791.  It
   is usually represented in dotted decimal notation.  See also: dot
   address, internet address, Internet Protocol, network address, subnet
   address, host address.

IP datagram
   See: datagram

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   See: Internetwork Packet eXchange

   See: Internet Registry

   See: Internet Relay Chat

   See: Internet Research Steering Group

   See: Internet Research Task Force

   See: Intermediate System

   See: Intermediate System-Intermediate System

   See: Integrated Services Digital Network

   See: International Organization for Standardization

ISO Development Environment (ISODE)
   Software that allows OSI services to use a TCP/IP network.
   Pronounced eye-so-dee-eee.  See also: Open Systems Interconnection,
   TCP/IP Protocol Suite.

   See: Internet Society

   See: ISO Development Environment

   See: International Telecommunications Union -
        Telecommunications Standards Sector

   See: International Telecommunications Union

   Joyce K. Reynolds

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   A popular implementation of TCP/IP and associated protocols for
   amateur packet radio systems.  See also: TCP/IP Protocol Suite.
   [Source: RFC1208]

   Kerberos is the security system of MIT's Project Athena.  It is based
   on symmetric key cryptography.  See also: encryption.

   A popular file transfer protocol developed by Columbia University.
   Because Kermit runs in most operating environments, it provides an
   easy method of file transfer.  Kermit is NOT the same as FTP.  See
   also: File Transfer Protocol
   [Source: MALAMUD]

   A "Knowledge Robot" is a program which seeks out information based on
   specified criteria.  "Knowbot," as trademarked by CNRI, refers
   specifically to the search engine for Knowbot Information Services.
   See also: Corporation for National Research Initiatives, X.500, white
   pages, whois, netfind.

Knowbot Information Services
   An experimental directory service.  See also: white pages, whois,

   See: Local Area Network

   Communication networks for computers may be organized as a set of
   more or less independent protocols, each in a different layer (also
   called level).  The lowest layer governs direct host-to-host
   communication between the hardware at different hosts; the highest
   consists of user applications.  Each layer builds on the layer
   beneath it.  For each layer, programs at different hosts use
   protocols appropriate to the layer to communicate with each other.
   TCP/IP has five layers of protocols; OSI has seven.  The advantages
   of different layers of protocols is that the methods of passing
   information from one layer to another are specified clearly as part
   of the protocol suite, and changes within a protocol layer are
   prevented from affecting the other layers.  This greatly simplifies
   the task of designing and maintaining communication programs.  See
   also: Open Systems Interconnection, TCP/IP Protocol Suite.

   See: Lightweight Directory Access Protocol

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Lightweight Directory Access Protocol
   This protocol provides access for management and browser applications
   that provide read/write interactive access to the X.500 Directory.
   See also: X.500.

   A pointer which may be used to retreive the file or data to which the
   pointer points.

list server
   An automated mailing list distribution system.  List servers handle
   the administrivia of mailing list maintenance, such as the adding and
   deleting of list members.

   A format for storage or transmission of binary data in which the
   least significant byte (bit) comes first.  See also: big-endian.
   [Source: RFC1208]

   See: Logical Link Control

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 data rates up to 100Mb/s.  See also: Ethernet, Fiber
   Distributed Data Interface, token ring, Metropolitan Area Network,
   Wide Area Network.
   [Source: NNSC]

Logical Link Control (LLC)
   The upper portion of the datalink layer, as defined in IEEE 802.2.
   The LLC sublayer presents a uniform interface to the user of the
   datalink service, usually the network layer.  Beneath the LLC
   sublayer is the MAC sublayer.  See also: 802.x, layer, Media Access

   No active participation on the part of a subscriber to an mailing
   list or USENET newsgroup.  A person who is lurking is just listening
   to the discussion.  Lurking is encouraged for beginners who need to
   get up to speed on the history of the group.  See also: Electronic
   Mail, mailing list, Usenet.
   [Source: LAQUEY]

   Lycos, Inc. is a new venture formed in late June 1995, to develop and

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   market the Lycos technology originally developed under the direction
   of Dr. Michael ("Fuzzy") Mauldin at Carnegie Mellon University.  The
   part of Lycos you see when you do a search is the search engine.
   "Lycos" comes from Lycosidae, a cosmopolitan family of relatively
   large active ground spiders (Wolf Spiders) that catch their prey by
   pursuit, rather than in a web.
   [Source: Lycos's FAQ]

   See: Media Access Control

MAC address
   The hardware address of a device connected to a shared media.  See
   also: Media Access Control, Ethernet, token ring.
   [Source: MALAMUD]

mail bridge
   A mail gateway that forwards electronic mail between two or more
   networks while ensuring that the messages it forwards meet certain
   administrative criteria.  A mail bridge is simply a specialized form
   of mail gateway that enforces an administrative policy with regard to
   what mail it forwards.  See also: Electronic Mail, mail gateway.
   [Source: NNSC]

Mail Exchange Record (MX Record)
   A DNS resource record type indicating which host can handle mail for
   a particular domain.  See also: Domain Name System, Electronic Mail.
   [Source: MALAMUD]

mail exploder
   Part of an electronic mail delivery system which allows a message to
   be delivered to a list of addresses.  Mail exploders are used to
   implement mailing lists.  Users send messages to a single address and
   the mail exploder takes care of delivery to the individual mailboxes
   in the list.  See also: Electronic Mail, email address, mailing list.
   [Source: RFC1208]

mail gateway
   A machine that connects two or more electronic mail systems
   (including dissimilar mail systems) and transfers messages between
   them.  Sometimes the mapping and translation can be quite complex,
   and it generally requires a store-and-forward scheme whereby the
   message is received from one system completely before it is
   transmitted to the next system, after suitable translations.  See
   also: Electronic Mail.
   [Source: RFC1208]

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mail path
   A series of machine names used to direct electronic mail from one
   user to another.  This system of email addressing has been used
   primarily in UUCP networks which are trying to eliminate its use
   altogether.  See also: bang path, email address, UNIX-to-UNIX CoPy.

mail server
   A software program that distributes files or information in response
   to requests sent via email.  Internet examples include Almanac and
   netlib.  Mail servers have also been used in Bitnet to provide FTP-
   like services.  See also: Bitnet, Electronic Mail, FTP.
   [Source: NWNET]

mailing list
   A list of email addresses, used by a mail exploder, to forward
   messages to groups of people.  Generally, a mailing list is used to
   discuss certain set of topics, and different mailing lists discuss
   different topics.  A mailing list may be moderated.  This means that
   messages sent to the list are actually sent to a moderator who
   determines whether or not to send the messages on to everyone else.
   Requests to subscribe to, or leave, a mailing list should ALWAYS be
   sent to the list's "-request" address (e.g. ietf-
   request@cnri.reston.va.us for the IETF mailing list) or majordomo
   server.  See also: Electronic Mail, mail exploder, email address,
   moderator, majordomo.

   A program which handles mailing list maintenance (affectionately
   known as administrivia) such as adding and removing addresses from
   mailing lists.  See also: email address, mailing list.

   See: 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 network device (e.g. router).  Standard, minimal
   MIBs have been defined, and vendors often have Private enterprise
   MIBs.  In theory, any SNMP manager can talk to any SNMP agent with a
   properly defined MIB.  See also: client-server model, Simple Network
   Management Protocol.
   [Source: BIG-LAN]

   A humorous term applied to packets that turn up unexpectedly on the
   wrong network because of bogus routing entries.  Also used as a name
   for a packet which has an altogether bogus (non-registered or ill-
   formed) internet address.

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   [Source: RFC1208]

Maximum Transmission Unit (MTU)
   The largest frame length which may be sent on a physical medium.  See
   also: frame, fragment, fragmentation.

   The Multicast Backbone is based on IP multicasting using class-D
   addresses.  The mbone concept was adopted at the March 1992 IETF in
   San Diego, during which it was used to audiocast to 40 people
   throughout the world.  At the following meeting, in Cambridge, the
   name mbone was adopted.  Since then the audiocast has become full
   two-way audio/video conferencing using two video channels, four audio
   channels, and involving hundreds of remote users.  See also:
   multicast, Internet Engineering Task Force.

MD-2, MD-4, MD-5
   See: Message Digest

Media Access Control (MAC)
   The lower portion of the datalink layer.  The MAC differs for various
   physical media.  See also: MAC Address, Ethernet, Logical Link
   Control, token ring.

Message Digest (MD-2, MD-4, MD-5)
   Message digests are algorithmic operations, generally performed on
   text, which produce a unique signature for that text.  MD-2,
   described in RFC 1319; MD-4, described in RFC 1320; and MD-5,
   described in RFC 1321 all produce a 128-bit signature.  They differ
   in their operating speed and resistance to crypto-analytic attack.
   Generally, one must be traded off for the other.

message switching
   See: packet switching

Metropolitan Area Network (MAN)
   A data network intended to serve an area approximating that of a
   large city.  Such networks are being implemented by innovative
   techniques, such as running fiber cables through subway tunnels.  A
   popular example of a MAN is SMDS.  See also: Local Area Network,
   Switched Multimegabit Data Service, Wide Area Network.
   [Source: NNSC]

   See: Management Information Base

Microcom Networking Protocol (MNP)
   A series of protocols built into most modems which error-check or

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   compress data being transmitted over a phone line.

mid-level network
   Mid-level networks (a.k.a. regionals) make up the second level of the
   Internet hierarchy.  They are the transit networks which connect the
   stub networks to the backbone networks.  See also: backbone,
   Internet, stub network, transit network.

   See: Multipurpose Internet Mail Extensions

   See: Microcom Networking Protocol

   A person, or small group of people, who manage moderated mailing
   lists and newsgroups.  Moderators are responsible for determining
   which email submissions are passed on to list.  See also: Electronic
   Mail, mailing list, Usenet.

   Multicast Open Shortest-Path First. See: Open Shortest-Path First.

   See: Maximum Transmission Unit

   See: Multi-User Dungeon

   A packet with a special destination address which multiple nodes on
   the network may be willing to receive.  See also: broadcast, unicast.

multihomed host
   A host which has more than one connection to a network.  The host may
   send and receive data over any of the links but will not route
   traffic for other nodes.  See also: host, router.
   [Source: MALAMUD]

Multipurpose Internet Mail Extensions (MIME)
   An extension to Internet email which provides the ability to transfer
   non-textual data, such as graphics, audio and fax.  See also:
   Electronic Mail

Multi-User Dungeon (MUD)
   Adventure, role playing games, or simulations played on the Internet.
   Devotees call them "text-based virtual reality adventures."  The
   games can feature fantasy combat, booby traps and magic.  Players

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   interact in real time and can change the "world" in the game as they
   play it.  Most MUDs are based on the Telnet protocol.  See also:
   [Source: LAQUEY]

MX Record
   See: Mail Exchange Record

   See: Negative Acknowledgment

name resolution
   The process of mapping a name into its corresponding address.  See
   also: Domain Name System.
   [Source: RFC1208]

   A commonly distributed set of names in which all names are unique.
   [Source: MALAMUD]

National Institute of Standards and Technology (NIST)
   United States governmental body that provides assistance in
   developing standards.  Formerly the National Bureau of Standards.
   [Source: MALAMUD]

National Research and Education Network (NREN)
   The NREN is the realization of an interconnected gigabit computer
   network devoted to Hign Performance Computing and Communications.
   See also: HPPC, IINREN.
   [Source: HPCC]

National Science Foundation (NSF)
   A U.S. government agency whose purpose is to promote the advancement
   of science.  NSF funds science researchers, scientific projects, and
   infrastructure to improve the quality of scientific research.  The
   NSFNET, funded by NSF, was once an essential part of academic and
   research communications.  It was a highspeed, hierarchical "network
   of networks."  At the highest level, it had a backbone network of
   nodes, interconnected with T3 (45Mbps) facilities which spaned the
   continental United States.  Attached to that were mid-level networks,
   and attached to the mid-levels were campus and local networks.  See
   also: backbone network, mid-level network.

Negative Acknowledgment (NAK)
   Response to the receipt of either a corrupted or unnexpected packet
   of information.  See also: Acknowledgement.

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   A research prototype to provide a simple Internet "white pages" user
   directory.  Developed at the University of Colorado, Boulder, it
   tries to locate telephone and email information given a person's name
   and a rough description of where the person works.  See also:
   Knowbot, whois, white pages, X.500.
   [Source: Ryan Moats]

   A pun on "etiquette" referring to proper behavior on a network.  RFC
   1855 (FYI 28) contains a netiquette guide produced by the User
   Services area of the IETF.  See also: Acceptable Use Policy, Internet
   Engineering Task Force.

   See: Usenet

   A computer network is a data communications system which
   interconnects computer systems at various different sites.  A network
   may be composed of any combination of LANs, MANs or WANs.  See also:
   Local Area Network, Metropolitan Area Network, Wide Area Network,

network address
   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, Internet Registry.

Network File System (NFS)
   A protocol developed by Sun Microsystems, and defined in RFC 1094
   (RFC 1813 defines Version 3), which allows a computer system to
   access files over a network as if they were on its local disks.  This
   protocol has been incorporated in products by more than two hundred
   companies, and is now a de facto Internet standard.
   [Source: NNSC]

Network Information Center (NIC)
   A NIC provides information, assistance and services to network users.
   See also: Network Operations Center.

Network Information Services (NIS)
   A set of services, generally provided by a NIC, to assist users in

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   using the network.  See also: Network Information Center.

Network News Transfer Protocol (NNTP)
   A protocol, defined in RFC 977, for the distribution, inquiry,
   retrieval, and posting of news articles.  See also: Usenet.

network mask
   See: address mask

network number
   See: network address

Network Operations Center (NOC)
   A location from which the operation of a network or internet is
   monitored.  Additionally, this center usually serves as a
   clearinghouse for connectivity problems and efforts to resolve those
   problems.  See also: Network Information Center.
   [Source: NNSC]

Network Time Protocol (NTP)
   A protocol that assures accurate local timekeeping with reference to
   radio and atomic clocks located on the Internet.  This protocol is
   capable of synchronizing distributed clocks within milliseconds over
   long time periods.  See also: Internet.
   [Source: NNSC]

   See: Network File System

   See: Network Information Center

   This is the domain name of the DDN NIC.  See also: Defense Data
   Network, Domain Name System, Network Information Center.

   See: Network Information Services

   See: National Institute of Standards and Technology

   See: Network News Transfer Protocol

   See: Network Operations Center

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Nodal Switching System (NSS)
   Main routing nodes in the NSFnet backbone.  See also: backbone,
   National Science Foundation.
   [Source: MALAMUD]

   An addressable device attached to a computer network.  See also:
   host, router.

   See: National Research and Education Network

   See: National Science Foundation

   See: Nodal Switching System

   See: Network Time Protocol

   See: Online Computer Library Catalog

   An octet is 8 bits.  This term is used in networking, rather than
   byte, because some systems have bytes that are not 8 bits long.

Online Computer Library Catalog
   OCLC is a nonprofit membership organization offering computer-based
   services to libraries, educational organizations, and their users.
   The OCLC library information network connects more than 10,000
   libraries worldwide.  Libraries use the OCLC System for cataloging,
   interlibrary loan, collection development, bibliographic
   verification, and reference searching.
   [Source: OCLC]

Open Shortest-Path First (OSPF)
   A link state, as opposed to distance vector, routing protocol.  It is
   an Internet standard IGP defined in RFCs 1583 and 1793.  The
   multicast version, MOSPF, is defined in RFC 1584.  See also: Interior
   Gateway Protocol, Routing Information Protocol.

Open Systems Interconnection (OSI)
   A suite of protocols, designed by ISO committees, to be the
   international standard computer network architecture.  See also:
   International Organization for Standardization.

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   See: Open Systems Interconnection

OSI Reference Model
   A seven-layer structure designed to describe computer network
   architectures and the way that data passes through them.  This model
   was developed by the ISO in 1978 to clearly define the interfaces in
   multivendor networks, and to provide users of those networks with
   conceptual guidelines in the construction of such networks.  See
   also: International Organization for Standardization.
   [Source: NNSC]

   See: Open Shortest-Path First

   The unit of data sent across a network.  "Packet" a generic term used
   to describe unit of data at all levels of the protocol stack, but it
   is most correctly used to describe application data units.  See also:
   datagram, frame.

Packet InterNet Groper (PING)
   A program used to test reachability of destinations by sending them
   an ICMP echo request and waiting for a reply.  The term is used as a
   verb: "Ping host X to see if it is up!"  See also: Internet Control
   Message Protocol.
   [Source: RFC1208]

Packet Switch Node (PSN)
   A dedicated computer whose purpose is to accept, route and forward
   packets in a packet switched network.  See also: packet switching,
   [Source: NNSC]

packet switching
   A communications paradigm in which packets (messages) are
   individually routed between hosts, with no previously established
   communication path.  See also: circuit switching, connection-
   oriented, connectionless.

   Public Domain

   See: Protocol Data Unit

   See: Privacy Enhanced Mail

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   See: Pretty Good Privacy

   See: Packet INternet Groper

Point Of Presence (POP)
   A site where there exists a collection of telecommunications
   equipment, usually digital leased lines and multi-protocol routers.

Point-to-Point Protocol (PPP)
   The Point-to-Point Protocol, defined in RFC 1661, provides a method
   for transmitting packets over serial point-to-point links.  There are
   many other RFCs which define extensions to the basic protocol.  See
   also: Serial Line IP.
   [Source: FYI4]

   See: Post Office Protocol and Point Of Presence

   A port is a transport layer demultiplexing value.  Each application
   has a unique port number associated with it.  See also: Transmission
   Control Protocol, User Datagram Protocol.

Post Office Protocol (POP)
   A protocol designed to allow single user hosts to read electronic
   mail from a server.  Version 3, the most recent and most widely used,
   is defined in RFC 1725.  See also: Electronic Mail.

Postal Telegraph and Telephone (PTT)
   Outside the USA, PTT refers to a telephone service provider, which is
   usually a monopoly, in a particular country.

   The person responsible for taking care of electronic mail problems,
   answering queries about users, and other related work at a site.  See
   also: Electronic Mail.
   [Source: ZEN]

   See: Point-to-Point Protocol

Pretty Good Privacy (PGP)
   A program, developed by Phil Zimmerman, which cryptographically
   protects files and electronic mail from being read by others.  It may
   also be used to digitally sign a document or message, thus
   authenticating the creator.  See also: encryption, Data Encryption

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   Standard, RSA.

Privacy Enhanced Mail (PEM)
   Internet email which provides confidentiality, authentication and
   message integrity using various encryption methods.  See also:
   Electronic Mail, encryption.

   A distributed filesystem which provides the user with the ability to
   create multiple views of a single collection of files distributed
   across the Internet.  Prospero provides a file naming system, and
   file access is provided by existing access methods (e.g. anonymous
   FTP and NFS).  The Prospero protocol is also used for communication
   between clients and servers in the archie system.  See also:
   anonymous FTP, archie, archive site, Gopher, Network File System,
   Wide Area Information Servers.

   A formal description of message formats and the rules two computers
   must follow to exchange those messages.  Protocols can describe low-
   level details of machine-to-machine interfaces (e.g., the order in
   which bits and bytes are sent across a wire) or high-level exchanges
   between allocation programs (e.g., the way in which two programs
   transfer a file across the Internet).
   [Source: MALAMUD]

protocol converter
   A device/program which translates between different protocols which
   serve similar functions (e.g. TCP and TP4).

Protocol Data Unit (PDU)
   "PDU" is internationalstandardscomitteespeak for packet.  See also:

protocol stack
   A layered set of protocols which work together to provide a set of
   network functions.  See also: layer, protocol.

proxy ARP
   The technique in which one machine, usually a router, answers ARP
   requests intended for another machine.  By "faking" its identity, the
   router accepts responsibility for routing packets to the "real"
   destination.  Proxy ARP allows a site to use a single IP address with
   two physical networks.  Subnetting would normally be a better
   solution.  See also: Address Resolution Protocol
   [Source: RFC1208]

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   See: Packet Switch Node.

   See: Postal, Telegraph and Telephone

   A backup of packets awaiting processing.

   Reseaux Associes pour la Recherche Europeenne.  See: Trans-European
   Research and Education Networking Association.

   See: Reverse Address Resolution Protocol

   Regional Bell Operating Company

Read The F*cking Manual (RTFM)
   This acronym is often used when someone asks a simple or common

Read The Source Code (RTSC)
   This acronym is often used when a software developer asks a question
   about undocumented code.

   The IP process in which a previously fragmented packet is reassembled
   before being passed to the transport layer.  See also: fragmentation.

   See: recursive

   See: mid-level network

remote login
   Operating on a remote computer, using a protocol over a computer
   network, as though locally attached.  See also: Telnet.

Remote Procedure Call (RPC)
   An easy and popular paradigm for implementing the client-server model
   of distributed computing.  In general, a request is sent to a remote
   system to execute a designated procedure, using arguments supplied,
   and the result returned to the caller.  There are many variations and
   subtleties in various implementations, resulting in a variety of
   different (incompatible) RPC protocols.

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   [Source: RFC1208]

   A device which propagates electrical signals from one cable to
   another.  See also: bridge, gateway, router.

Request For Comments (RFC)
   The document series, begun in 1969, which describes the Internet
   suite of protocols and related experiments.  Not all (in fact very
   few) RFCs describe Internet standards, but all Internet standards are
   written up as RFCs.  The RFC series of documents is unusual in that
   the proposed protocols are forwarded by the Internet research and
   development community, acting on their own behalf, as opposed to the
   formally reviewed and standardized protocols that are promoted by
   organizations such as CCITT and ANSI.  See also: BCP, FYI, STD.

Reseaux IP Europeens (RIPE)
   A collaboration between European networks which use the TCP/IP
   protocol suite.

Reverse Address Resolution Protocol (RARP)
   A protocol, defined in RFC 903, which provides the reverse function
   of ARP.  RARP maps a hardware (MAC) address to an internet address.
   It is used primarily by diskless nodes when they first initialize to
   find their internet address.  See also: Address Resolution Protocol,
   BOOTP, internet address, MAC address.

   See: Request For Comments

RFC 822
   The Internet standard format for electronic mail message headers.
   Mail experts often refer to "822 messages."  The name comes from RFC
   822, which contains the specification.  822 format was previously
   known as 733 format.  See also: Electronic Mail.
   [Source: COMER]

   See: Routing Information Protocol

   See: Reseaux IP Europeenne

Round-Trip Time (RTT)
   A measure of the current delay on a network.
   [Source: MALAMUD]

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   The path that network traffic takes from its source to its
   destination.  Also, a possible path from a given host to another host
   or destination.

   Route Daemon.  A program which runs under 4.2BSD/4.3BSD UNIX systems
   (and derived operating systems) to propagate routes among machines on
   a local area network, using the RIP protocol.  Pronounced "route-
   dee".  See also: Routing Information Protocol, gated.

   A device which forwards traffic between networks.  The forwarding
   decision is based on network layer information and routing tables,
   often constructed by routing protocols.  See also: bridge, gateway,
   Exterior Gateway Protocol, Interior Gateway Protocol.

   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 domain
   A set of routers exchanging routing information within an
   administrative domain.  See also: Administrative Domain, router.

Routing Information Protocol (RIP)
   A distance vector, as opposed to link state, routing protocol.
   Version 1 was defined in RFC 1058.  The Internet Standard version
   (RIPv2)is defined in RFC 2453 (STD 56).  See also: Interior Gateway
   Protocol, Open Shortest-Path First.

   See: Remote Procedure Call

   A public-key cryptographic system which may be used for encryption
   and authentication.  It was invented in 1977 and named for its
   inventors: Ron Rivest, Adi Shamir, and Leonard Adleman.  See also:
   encryption, Data Encryption Standard, Pretty Good Privacy.

   See: Read The F*cking Manual

   See: Read The Source Code

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   See: Round-Trip Time

   See: Synchronous Digital Hierarchy

Serial Line IP (SLIP)
   A protocol used to run IP over serial lines, such as telephone
   circuits or RS-232 cables, interconnecting two systems.  SLIP is
   defined in RFC 1055, but is not an Internet Standard.  It is being
   replaced by PPP.  See also: Point-to-Point Protocol.

   A provider of resources (e.g. file servers and name servers).  See
   also: client, Domain Name System, Network File System.

   See: Standardized Generalized Markup Language

   Special Interest Group

   The three or four line message at the bottom of a piece of email or a
   Usenet article which identifies the sender.  Large signatures (over
   five lines) are generally frowned upon.  See also: Electronic Mail,

Simple Mail Transfer Protocol (SMTP)
   A protocol used to transfer electronic mail between computers.  It is
   specified in RFC 821, with extensions specified in many other RFCs.
   It is a server to server protocol, so other protocols are used to
   access the messages.  See also: Electronic Mail, Post Office
   Protocol, RFC 822.

Simple Network Management Protocol (SNMP)
   The Internet standard protocol developed to manage nodes on an IP
   network.  The first version is defined in RFC 1157 (STD 15).  SNMPv2
   (version 2) is defined in too many RFCs to list.  It is currently
   possible to manage wiring hubs, toasters, jukeboxes, etc.  See also:
   Management Information Base.

   See: Serial Line IP

   See: Switched Multimegabit Data Service

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   See: Structure of Management Information

   See: Simple Mail Transfer Protocol

   See: Systems Network Architecture

snail mail
   A pejorative term referring to the U.S. postal service.

   See: Simple Network Management Protocol

   See: Synchronous Optical NETwork

Standardized Generalized Markup Language (SGML)
   An international standard for the definition of system-independent,
   device-independent methods of representing text in electronic form.
   See also: Hypertext Markup Language.

   A subseries of RFCs that specify Internet standards.  The official
   list of Internet standards is in STD 1.  See also: Request For

   A type of transport service that allows its client to send data in a
   continuous stream.  The transport service will guarantee that all
   data will be delivered to the other end in the same order as sent and
   without duplicates.  See also: Transmission Control Protocol.
   [Source: MALAMUD]

Structure of Management Information (SMI)
   The rules used to define the objects that can be accessed via a
   network management protocol.  These rules are defined in RFC 1155
   (STD 17).  The acronym is pronounced "Ess Em Eye."  See also:
   Management Information Base.  .br [Source: RFC1208]

stub network
   A stub network only carries packets to and from local hosts.  Even if
   it has paths to more than one other network, it does not carry
   traffic for other networks.  See also: backbone, transit network.

   A portion of a network, which may be a physically independent network

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   segment, which shares a network address with other portions of the
   network and is distinguished by a subnet number.  A subnet is to a
   network what a network is to an internet.  See also: internet,
   [Source: FYI4]

subnet address
   The subnet portion of an IP address.  In a subnetted network, the
   host portion of an IP address is split into a subnet portion and a
   host portion using an address (subnet) mask.  See also: address mask,
   IP address, network address, host address.

subnet mask
   See: address mask

subnet number
   See: subnet address

   An aggregation of IP network addresses advertised as a single
   classless network address.  For example, given four Class C IP
   networks:,, and, each
   having the intrinsic network mask of; one can advertise
   the address with a subnet mask of  See also:
   IP address, network address, network mask, Classless Inter-domain

Switched Multimegabit Data Service (SMDS)
   An emerging high-speed datagram-based public data network service
   developed by Bellcore and expected to be widely used by telephone
   companies as the basis for their data networks.  See also:
   Metropolitan Area Network.
   [Source: RFC1208]

Synchronous Digital Hierarchy (SDH)
   The European standard for high-speed data communications over fiber-
   optic media.  The transmission rates range from 155.52Mbps to

Synchronous Optical NETwork (SONET)
   SONET is an international standard for high-speed data communications
   over fiber-optic media.  The transmission rates range from 51.84Mbps
   to 2.5Gbps.

Systems Network Architecture (SNA)
   A proprietary networking architecture used by IBM and IBM-compatible
   mainframe computers.
   [Source: NNSC]

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   A term for a digital carrier facility used to transmit a DS-1
   formatted digital signal at 1.544 megabits per second.

   A term for a digital carrier facility used to transmit a DS-3
   formatted digital signal at 44.746 megabits per second.
   [Source: FYI4]

   See: Terminal Access Controller (TAC)

   A protocol which allows two people on remote computers to communicate
   in a real-time fashion.  See also: Internet Relay Chat.

   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 runs over IP.  See also: IP, ICMP, TCP,
   UDP, FTP, Telnet, SMTP, SNMP.

   The original name for what is now SprintNet.  It should not be
   confused with the Telnet protocol or application program.

   Telnet is the Internet standard protocol for remote terminal
   connection service.  It is defined in RFC 854 and extended with
   options by many other RFCs.

   See: Trans-European Research and Education Networking Association

Terminal Access Controller (TAC)
   A device which was once used to connect terminals to the Internet,
   usually using dialup modem connections and the TACACS protocol.
   While the device is no longer in use, TACACS+ is a protocol in
   current use.

terminal emulator
   A program that allows a computer to emulate a terminal.  The
   workstation thus appears as a terminal to the remote host.
   [Source: MALAMUD]

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terminal server
   A device which connects many terminals to a LAN through one network
   connection.  A terminal server can also connect many network users to
   its asynchronous ports for dial-out capabilities and printer access.
   See also: Local Area Network.

Three Letter Acronym (TLA)
   A tribute to the use of acronyms in the computer field.  See also:
   Extended Four Letter Acronym.

Time to Live (TTL)
   A field in the IP header which indicates how long this packet should
   be allowed to survive before being discarded.  It is primarily used
   as a hop count.  See also: Internet Protocol.
   [Source: MALAMUD]

   See: Three Letter Acronym

   A variant of the Telnet program that allows one to attach to IBM
   mainframes and use the mainframe as if you had a 3270 or similar
   [Source: BIG-LAN]

token ring
   A token ring is a type of LAN with nodes wired into a ring.  Each
   node constantly passes a control message (token) on to the next;
   whichever node has the token can send a message.  Often, "Token Ring"
   is used to refer to the IEEE 802.5 token ring standard, which is the
   most common type of token ring.  See also: 802.x, Local Area Network.

   A network topology shows the computers and the links between them.  A
   network layer must stay abreast of the current network topology to be
   able to route packets to their final destination.
   [Source: MALAMUD]

   A program available on many systems which traces the path a packet
   takes to a destination.  It is mostly used to debug routing problems
   between hosts.  There is also a traceroute protocol defined in RFC

Trans-European Research and Education Networking Association (TERENA)
   TERENA was formed in October 1994 by the merger of RARE and EARN to
   promote and participate in the development of a high quality
   international information and telecommunications infrastructure for

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   the benefit of research and education.  See also: Reseaux Associes
   pour la Recherche Europeenne, European Academic and Research Network.
   [Source: TERENA Statutes]

   Transmitter-receiver.  The physical device that connects a host
   interface to a local area network, such as Ethernet.  Ethernet
   transceivers contain electronics that apply signals to the cable and
   sense collisions.
   [Source: RFC1208]

transit network
   A transit network passes traffic between networks in addition to
   carrying traffic for its own hosts.  It must have paths to at least
   two other networks.  See also: backbone, stub network.

Transmission Control Protocol (TCP)
   An Internet Standard transport layer protocol defined in RFC 793.  It
   is connection-oriented and stream-oriented, as opposed to UDP.  See
   also: connection-oriented, stream-oriented, User Datagram Protocol.

Trojan Horse
   A computer program which carries within itself a means to allow the
   creator of the program access to the system using it.  See also:
   virus, worm.

   Ta-Ta For Now

   See: Time to Live

   Tunnelling refers to encapsulation of protocol A within protocol B,
   such that A treats B as though it were a datalink layer.  Tunnelling
   is used to get data between administrative domains which use a
   protocol that is not supported by the internet connecting those
   domains.  See also: Administrative Domain.

twisted pair
   A type of cable in which pairs of conductors are twisted together to
   produce certain electrical properties.

   See: User Datagram Protocol

   An address which only one host will recognize.  See also: broadcast,

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Uniform Resource Locators (URL)
   A URL is a compact (most of the time) string representation for a
   resource available on the Internet.  URLs are primarily used to
   retrieve information using WWW.  The syntax and semantics for URLs
   are defined in RFC 1738.  See also: World Wide Web.

Universal Time Coordinated (UTC)
   This is Greenwich Mean Time.
   [Source: MALAMUD]

   This was initially a program run under the UNIX operating system that
   allowed one UNIX system to send files to another UNIX system via
   dial-up phone lines.  Today, the term is more commonly used to
   describe the large international network which uses the UUCP protocol
   to pass news and electronic mail.  See also: Electronic Mail, Usenet.

urban legend
   A story, which may have started with a grain of truth, that has been
   embroidered and retold until it has passed into the realm of myth.
   It is an interesting phenonmenon that these stories get spread so
   far, so fast and so often.  Urban legends never die, they just end up
   on the Internet!  Some legends that periodically make their rounds
   include "The Infamous Modem Tax," "Craig Shergold/Brain Tumor/Get
   Well Cards," and "The $250 Cookie Recipe."
   [Source: LAQUEY]

   See: Uniform Resource Locators

   A collection of thousands of topically named newsgroups, the
   computers which run the protocols, and the people who read and submit
   Usenet news.  Not all Internet hosts subscribe to Usenet and not all
   Usenet hosts are on the Internet.  See also: Network News Transfer
   Protocol, UNIX-to-UNIX CoPy.
   [Source: NWNET]

User Datagram Protocol (UDP)
   An Internet Standard transport layer protocol defined in RFC 768.  It
   is a connectionless protocol which adds a level of reliability and
   multiplexing to IP.  See also: connectionless, Transmission Control

   See: Universal Time Coordinated

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   See: UNIX-to-UNIX CoPy

   A program which reverses the effect of uuencode.  See also: uuencode.

   A program which reversibly converts a binary file in ASCII.  It is
   used to send binary files via email, which generally does not allow
   (or garbles) the transmission of binary information.  The original
   binary can be restored with uudecode.  The encoding process generally
   creates an ASCII file larger than the original binary, so compressing
   the binary before running uuencode is highly recommended.

   A Gopher utility which effectively searches Gopher servers based on a
   user's list of keywords.  The name was chosen to be a "mate" to
   another utility named "Archie."  It later became an acronym for Very
   Easy Rodent Oriented Netwide Index to Computer Archives.  See also:
   archie, Gopher.

virtual circuit
   A network service which provides connection-oriented service without
   necessarily doing circuit-switching.  See also: connection-oriented.

   A program which replicates itself on computer systems by
   incorporating itself into other programs which are shared among
   computer systems.  See also: Trojan Horse, worm.

   See: World Wide Web

   See: Wide Area Information Servers

   See: Wide area network

   A WWW search engine.  The aim of the WebCrawler Project is to provide
   a high-quality, fast, and free Internet search service.  The
   WebCrawler may be reached at "http://webcrawler.com/".
   [Source: WebCrawler's "WebCrawler Facts"]

   See: Working Group

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white pages
   The Internet supports several databases that contain basic
   information about users, such as e-mail addresses, telephone numbers,
   and postal addresses.  These databases can be searched to get
   information about particular individuals.  Because they serve a
   function akin to the telephone book, these databases are often
   referred to as "white pages."  See also: Knowbot, netfind, whois,
   X.500, InterNIC.

   An Internet program which allows users to query a database of people
   and other Internet entities, such as domains, networks, and hosts.
   The primary database is kept at the InterNIC.  The information stored
   includes a person's company name, address, phone number and email
   address.  The latest version of the protocol, WHOIS++, is defined in
   RFCs 1834 and 1835.  See also: InterNIC, white pages, Knowbot,
   netfind, X.500.

Wide Area Information Servers (WAIS)
   A distributed information service which offers simple natural
   language input, indexed searching for fast retrieval, and a
   "relevance feedback" mechanism which allows the results of initial
   searches to influence future searches.  Public domain implementations
   are available.  See also: archie, Gopher, Prospero.

Wide Area Network (WAN)
   A network, usually constructed with serial lines, which covers a
   large geographic area.  See also: Local Area Network, Metropolitan
   Area Network.

Working Group (WG)
   A working group, within the IETF, is a group of people who work under
   a charter to achieve a certain goal.  That goal may be the creation
   of an Informational document, the creation of a protocol
   specification, or the resolution of problems in the Internet.  Most
   working groups have a finite lifetime.  That is, once a working group
   has achieved its goal, it disbands.  There is no official membership
   for a working group.  Unofficially, a working group member is
   somebody who is on that working group's mailing list; however, anyone
   may attend a working group meeting.  See also: Internet Engineering
   Task Force, Birds Of a Feather.

World Wide Web (WWW, W3)
   A hypertext-based, distributed information system created by
   researchers at CERN in Switzerland.  Users may create, edit or browse
   hypertext documents.  The clients and servers are freely available.

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   A computer program which replicates itself and is self-propagating.
   Worms, as opposed to viruses, are meant to spawn in network
   environments.  Network worms were first defined by Shoch & Hupp of
   Xerox in ACM Communications (March 1982).  The Internet worm of
   November 1988 is perhaps the most famous; it successfully propagated
   itself on over 6,000 systems across the Internet.  See also: Trojan
   Horse, virus.

   With Respect To

   See: World Wide Web

   What You See is What You Get

   X is the name for TCP/IP based network-oriented window systems.
   Network window systems allow a program to use a display on a
   different computer.   The most widely-implemented window system is
   X11 - a component of MIT's Project Athena.

   A data communications interface specification developed to describe
   how data passes into and out of public data communications networks.
   The CCITT and ISO approved protocol suite defines protocol layers 1
   through 3.

   The CCITT and ISO standard for electronic mail.  It is widely used in
   Europe and Canada.

   The CCITT and ISO standard for electronic directory services.  See
   also: white pages, Knowbot, whois.

   See: eXternal Data Representation

Xerox Network System (XNS)
   A protocol suite developed by Xerox Corporation to run on LAN and WAN
   networks, where the LANs are typically Ethernet.  Implementations
   exist for both Xerox's workstations and 4.3BSD, and 4.3BSD-derived,
   systems.  XNS denotes not only the protocol stack, but also an
   architecture of standard programming interfaces, conventions, and
   service functions for authentication, directory, filing, email, and

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   remote procedure call.  XNS is also the name of Xerox's
   implementation.  See also: Ethernet, Berkeley Software Distribution,
   Local Area Network, Wide Area Network.
   [Source: Jeff Hodges]

   See: Xerox Network System


   Yahoo! is a hierarchical subject-oriented guide for the World Wide
   Web and Internet.  Yahoo! lists sites and categorizes them into
   appropriate subject categories.  Yahoo! may be reached at
   [Source: Yahoo's "What is Yahoo?"]

Yellow Pages (YP)
   A historic (i.e., no longer in use) service used by UNIX
   administrators to manage databases distributed across a network.

   See: Yellow Pages

   A logical group of network devices.

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BIG-LAN "BIG-LAN Frequently Asked Questions Memo", BIG-LAN DIGEST V4:I8,
        February 14, 1992.

COMER   Comer, Douglas, "Internetworking with TCP/IP: Principles,
        Protocols and Architecture", Prentice Hall, Englewood Cliffs,
        NJ, 1991.

FYI4    Malkin, G., A. Marine, "FYI on Questions and Answers: Answers to
        Commonly asked "New Internet User" Questions", RFC 1325 (FYI 4),
        Xylogics, SRI, May 1992.

HACKER  "THIS IS THE JARGON FILE", Version 2.9.8, January 1992.

HPCC    "Grand Challenges 1993: High Performance Computing and
        Communications", Committee on Physical, Mathmatical and
        Engineering Sciences of the Federal Coordinating Council for
        Science, Engineering and Technology.

MALAMUD Malamud, Carl, "Analyzing Sun Networks", Van Nostrand Reinhold,
        New York, NY, 1992.

NNSC    "NNSC's Hypercard Tour of the Internet".

LAQUEY  LaQuey, Tracy, with Jeanne C. Ryer, "The Internet Companion: A
        Beginner's Guide to Global Networking", Addison-Wesley, Reading,
        MA, 1992.

NWNET   Kochmer, Jonathan, and NorthWestNet, "The Internet Passport:
        NorthWestNets Guide to Our World Online", NorthWestNet,
        Bellevue, WA, 1992.

RFC1208 Jacobsen, O., D. Lynch, "A Glossary of Networking Terms", RFC
        1208, Interop, Inc., March 1991.

        (STD 1), March 1996.

STD2    Reynolds, J., J. Postel, "ASSIGNED NUMBERS", RFC 1700 (STD 2),
        ISI, October 1994.

TAN     Tanenbaum, Andrew S., "Computer Networks; 2nd ed.", Prentice
        Hall, Englewood Cliffs, NJ, 1989.

ZEN     Kehoe, Brendan P., "Zen and the Art of the Internet", February

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Security Considerations

While security is not explicitly discussed in this document, some of the
glossary's entries are security related.  See the entries for Access
Control List (ACL), authentication, Computer Emergency Response Team
(CERT), cracker, Data Encryption Key (DEK), Data Encryption Standard
(DES), encryption, Kerberos, Message Digest (MD-2, MD-4, MD-5), Pretty
Good Privacy (PGP), Privacy Enhanced Mail (PEM), RSA, Trojan Horse,
virus, and worm.

Editor's Address

Gary Scott Malkin
Nortel Networks
600 Tech Park
Billerica, MA 01821

Phone:  (978) 288-3634
Email:  gmalkin@nortelnetworks.com

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