Network Working Group                                          G. Malkin
Request for Comments: 1392                                Xylogics, Inc.
FYI: 18                                                 T. LaQuey Parker
                                                                 UTexas
                                                                Editors
                                                           January 1993


                       Internet Users' Glossary

Status of this Memo

  This memo provides information for the Internet community.  It does
  not specify an Internet standard.  Distribution of this memo is
  unlimited.


Abstract

  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.


Acknowledgements

  This document is the work of the User Glossary Working Group of the
  User Services Area of the Internet Engineering Task Force (IETF).
  Special thanks go to Jon Postel for his definitive definition of
  "datagram".


Table of Contents

  non-letter  . .  2      I . . . . . . . 23      R . . . . . . . 40
  A . . . . . . .  2      J . . . . . . . 29      S . . . . . . . 43
  B . . . . . . .  6      K . . . . . . . 29      T . . . . . . . 45
  C . . . . . . .  9      L . . . . . . . 29      U . . . . . . . 48
  D . . . . . . . 12      M . . . . . . . 30      V . . . . . . . 49
  E . . . . . . . 16      N . . . . . . . 33      W . . . . . . . 49
  F . . . . . . . 18      O . . . . . . . 36      X . . . . . . . 50
  G . . . . . . . 20      P . . . . . . . 37      Y . . . . . . . 51
  H . . . . . . . 21      Q . . . . . . . 40      Z . . . . . . . 51

  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 52
  Security Considerations . . . . . . . . . . . . . . . . . . . . 53
  Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . 53



User Glossary Working Group                                     [Page 1]

RFC 1392                   Internet Glossary                January 1993


Glossary

  10BaseT
     A variant of Ethernet which allows stations to be attached via
     twisted pair cable.  See also: Ethernet, twisted pair.

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

  822
     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 Rules.

  Acceptable Use Policy (AUP)
     Many transit networks have policies which restrict the use to
     which the network may be put.  A well known example is NSFNET's
     AUP which does not allow commercial use.  Enforcement of AUPs
     varies with the network.  See also: National Science Foundation.

  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.

  ACK
     See: Acknowledgment



User Glossary Working Group                                     [Page 2]

RFC 1392                   Internet Glossary                January 1993


  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]

  ACL
     See: Access Control List

  AD
     See: Administrative Domain

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

  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 can be determined by the encoding inherent in an IP
     address.

  address resolution
     Conversion of an internet address into the corresponding physical
     address.

  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.  It is defined in RFC 826.  See also: proxy ARP.

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

  Advanced Research Projects Agency Network (ARPANET)
     A pioneering longhaul network funded by ARPA (now DARPA).  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: Defense Advanced
     Research Projects Agency.
     [Source: FYI4]



User Glossary Working Group                                     [Page 3]

RFC 1392                   Internet Glossary                January 1993


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

  alias
     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.

  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.

  ANSI
     See: American National Standards Institute

  API
     See: Application Program Interface

  Appletalk
     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]

  application
     A program that performs a function directly for a user.  FTP, mail



User Glossary Working Group                                     [Page 4]

RFC 1392                   Internet Glossary                January 1993


     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]

  archie
     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 Servers.

  archive site
     A machine that provides access to a collection of files across the
     Internet.  An "anonymous FTP archive site", for example, provides
     access to this material via the FTP protocol.  See also: anonymous
     FTP, archie, Gopher, Prospero, Wide Area Information Servers.

  ARP
     See: Address Resolution Protocol

  ARPA
     See: Defense Advanced Research Projects Agency

  ARPANET
     See: Advanced Research Projects Agency Network

  AS
     See: Autonomous System

  ASCII
     See: American Standard Code for Information Interchange

  ASN.1
     See: Abstract Syntax Notation One

  assigned numbers
     The RFC [STD2] which documents the currently assigned values from



User Glossary Working Group                                     [Page 5]

RFC 1392                   Internet Glossary                January 1993


     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 method for the dynamic allocation of bandwidth using a fixed-
     size packet (called a cell).  ATM is also known as "fast packet".

  ATM
     See: Asynchronous Transfer Mode

  AUP
     See: Acceptable Use Policy

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

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

  backbone
     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.

  bandwidth
     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.

  baseband
     A transmission medium through which digital signals are sent
     without complicated frequency shifting.  In general, only one



User Glossary Working Group                                     [Page 6]

RFC 1392                   Internet Glossary                January 1993


     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]

  BBS
     See: Bulletin Board System

  BCNU
     Be Seein' You

  BER
     See: Basic Encoding Rules

  Berkeley Internet Name Domain (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.

  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]

  BGP
     See: Border Gateway Protocol

  big-endian
     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-endian.
     [Source: RFC1208]




User Glossary Working Group                                     [Page 7]

RFC 1392                   Internet Glossary                January 1993


  binary
     11001001

  BIND
     See: Berkeley Internet Name Domain

  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.

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

  BOF
     See: Birds Of a Feather

  BOOTP
     The Bootstrap Protocol, described in RFCs 951 and 1084, is used
     for booting diskless nodes.  See also: Reverse Address Resolution
     Protocol.

  Border Gateway Protocol (BGP)
     The Border Gateway Protocol is an exterior gateway protocol
     defined in RFCs 1267 and 1268.  It's design is based on experience
     gained with EGP, as defined in STD 18, RFC 904, and EGP usage in
     the NSFNET Backbone, as described in RFCs 1092 and 1093.  See
     also: Exterior Gateway Protocol.

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

  bridge
     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.

  broadband
     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.



User Glossary Working Group                                     [Page 8]

RFC 1392                   Internet Glossary                January 1993


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

  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.

  brouter
     A device which bridges some packets (i.e., forwards based on
     datalink layer information) and routes other packets (i.e.,
     forwards based on network layer information).  The bridge/route
     decision is based on configuration information.  See also: bridge,
     router.

  BSD
     See: Berkeley Software Distribution

  BTW
     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]

  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.

  CCIRN
     See: Coordinating Committee for Intercontinental Research Networks

  CCITT
     See: Comite Consultatif International de Telegraphique et
     Telephonique





User Glossary Working Group                                     [Page 9]

RFC 1392                   Internet Glossary                January 1993


  CERT
     See: Computer Emergency Response Team

  checksum
     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 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.
     [Source: NNSC]

  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.

  client
     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.

  CNI
     See: Coalition for Networked Information

  Coalition for Networked Information (CNI)
     A consortium formed by American Research Libraries, CAUSE, and
     EDUCOM 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
     (CCITT)
     This organization is part of the United National International
     Telecommunications Union (ITU) 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.
     [Source: NNSC]



User Glossary Working Group                                    [Page 10]

RFC 1392                   Internet Glossary                January 1993


  Computer Emergency Response Team (CERT)
     The CERT was formed by DARPA 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 "[email protected]" and by telephone at
     +1-412-268-7090 (24-hour hotline).  See also: Defense Advanced
     Research Projects Agency, worm.

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

  connection-oriented
     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.

  connectionless
     The data communication method in which communication occurs
     between hosts with no previous setup.  Packets between two hosts
     may take different routes, as each is independent of the other.
     UDP 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.  See also: Federal Networking
     Council, RARE.
     [Source: MALAMUD]

  core gateway
     Historically, one of a set of gateways (routers) operated by the



User Glossary Working Group                                    [Page 11]

RFC 1392                   Internet Glossary                January 1993


     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 gateway.
     [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]

  cracker
     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.

  CRC
     See: cyclic redundancy check

  CREN
     See: Corporation for Research and Educational Networking

  CWIS
     See: Campus Wide Information system

  Cyberspace
     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]

  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.
     [Source: MALAMUD]

  DARPA
     See: Defense 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.



User Glossary Working Group                                    [Page 12]

RFC 1392                   Internet Glossary                January 1993


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

  datagram
     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, packet.
     [Source: J. Postel]

  DCA
     See: Defense Information Systems Agency

  DCE
     Data Circuit-terminating Equipment

  DCE
     See: Distributed Computing Environment

  DDN
     See: Defense Data Network

  DDN NIC
     See: Defense Data Network Network Information Center

  DECnet
     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 Advanced Research Projects Agency (DARPA)
     An agency of the U.S. Department of Defense responsible for the
     development of new technology for use by the military.  DARPA
     (formerly known as 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]

  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



User Glossary Working Group                                    [Page 13]

RFC 1392                   Internet Glossary                January 1993


     is used to connect military installations and is managed by the
     Defense Information Systems Agency.  See also: Defense Information
     Systems Agency.

  Defense Data Network Network Information Center (DDN NIC)
     Often called "The NIC", the DDN NIC's primary responsibility is
     the assignment of Internet network addresses and Autonomous System
     numbers, the administration of the root domain, and providing
     information and support services to the DDN.  It is also a primary
     repository for RFCs.  See also: Autonomous System, network
     address, Internet Registry, Network Information Center, Request
     For Comments.

  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.

  DEK
     See: Data Encryption Key

  DES
     See: Data Encryption Standard

  dialup
     A temporary, as opposed to dedicated, connection between machines
     established over a standard phone line.

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




User Glossary Working Group                                    [Page 14]

RFC 1392                   Internet Glossary                January 1993


  DISA
     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

  DNS
     See: Domain Name System

  domain
     "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 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.  For example, .US (United
     States), .UK (United Kingdom), .AU (Australia).  It is defined in
     STD 13, RFCs 1034 and 1035.  See also: Fully Qualified Domain
     Name.

  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]





User Glossary Working Group                                    [Page 15]

RFC 1392                   Internet Glossary                January 1993


  DS1
     A framing specification for T-1 synchronous lines.  See also: T1

  DS3
     A framing specification for T-3 synchronous lines.  See also: T3

  DSA
     See: Directory System Agent

  DTE
     Data Terminal Equipment

  DUA
     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]

  EARN
     See: European Academic and Research Network

  EBCDIC
     See: Extended Binary Coded Decimal Interchange Code

  Ebone
     A pan-European backbone service.

  EFF
     See: Electronic Frontier Foundation

  EFLA
     See: Extended Four Letter Acronym

  EGP
     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.



User Glossary Working Group                                    [Page 16]

RFC 1392                   Internet Glossary                January 1993


     Electronic mail is one of the most popular uses of the Internet.
     [Source: NNSC]

  email
     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 "[email protected]".  See also: bang path, mail path, UNIX-
     to-UNIX CoPy.
     [Source: ZEN]

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

  encryption
     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.

  Ethernet
     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.
     [Source: COMER]

  European Academic and Research Network (EARN)
     A network connecting European academic and research institutions
     with electronic mail and file transfer services using the Bitnet
     protocol.  See also: Bitnet





User Glossary Working Group                                    [Page 17]

RFC 1392                   Internet Glossary                January 1993


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

  Extended Four Letter Acronym (EFLA)
     A recognition of the fact that there are far too many TLAs.  See
     also: Three Letter Acronym.
     [Source: K. Morgan]

  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 STD 18, 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 RFC 1014.  It is similar to ASN.1.
     See also: Abstract Syntax Notation One.
     [Source: RFC1208]

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

  FAQ
     Frequently Asked Question

  FDDI
     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 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,
     DARPA, NSF, NASA, and HHS.  See also: Defense Advanced Research
     Projects Agency, National Science Foundation.





User Glossary Working Group                                    [Page 18]

RFC 1392                   Internet Glossary                January 1993


  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.

  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.  It is defined in STD 9, RFC 959.  See also: anonymous
     FTP.

  finger
     A program that displays information about a particular user, or
     all users, logged on the local system or on a remote system.  It
     typically shows full name, last login time, idle time, terminal
     line, and terminal location (where applicable).  It may also
     display plan and project files left by the user.

  FIX
     See: Federal Information Exchange

  flame
     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

  FNC
     See: Federal Networking Council

  For Your Information (FYI)
     A subseries of RFCs that are not technical standards or
     descriptions of protocols.  FYIs convey general information about
     topics related to TCP/IP or the Internet.  See also: Request For
     Comments, STD.

  FQDN
     See: Fully Qualified Domain Name





User Glossary Working Group                                    [Page 19]

RFC 1392                   Internet Glossary                January 1993


  fragment
     A piece of a packet.  When a router is forwarding an IP packet to
     a network that has a maximum packet size smaller than the 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.

  fragmentation
     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.

  frame
     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.

  freenet
     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]

  FTP
     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.

  FYI
     See: For Your Information

  gross
     A dozen dozen (144).

  gated
     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".



User Glossary Working Group                                    [Page 20]

RFC 1392                   Internet Glossary                January 1993


     Pronounced "gate-dee".  See also: Exterior Gateway Protocol, Open
     Shortest Path First..., Routing Information Protocol, routed.

  gateway
     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.

  Gopher
     A distributed information service that makes available
     hierarchical collections of information across the Internet.
     Gopher uses a simple protocol 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.

  GOSIP
     See: Government OSI Profile

  Government OSI Profile
     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.
     [Source: BIG-LAN]

  hacker
     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.

  header
     The portion of a packet, preceding the actual data, containing
     source and destination addresses, and error checking and other
     fields.  A header is also the part of an electronic mail message
     that precedes the body of a message and contains, among other
     things, the message originator, date and time.  See also:
     Electronic Mail, packet.

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



User Glossary Working Group                                    [Page 21]

RFC 1392                   Internet Glossary                January 1993


  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]

  HIPPI
     See: High Performance Parallel Interface

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

  host
     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

  hostname
     The name given to a machine.  See also: Fully Qualified Domain



User Glossary Working Group                                    [Page 22]

RFC 1392                   Internet Glossary                January 1993


     Name.
     [Source: ZEN]

  host number
     See: host address

  HPCC
     See: High Performance Computing and Communications

  hub
     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
     network.
     [Source: MALAMUD]

  I-D
     See: Internet-Draft

  IAB
     See: Internet Architecture Board

  IANA
     See: Internet Assigned Numbers Authority

  ICMP
     See: Internet Control Message Protocol

  IEEE
     Institute of Electrical and Electronics Engineers

  IEEE 802
     See: 802.x

  IEN
     See: Internet Experiment Note

  IESG
     See: Internet Engineering Steering Group

  IETF
     See: Internet Engineering Task Force

  IINREN
     See: Interagency Interim National Research and Education Network

  IGP
     See: Interior Gateway Protocol



User Glossary Working Group                                    [Page 23]

RFC 1392                   Internet Glossary                January 1993


  IMHO
     In My Humble Opinion

  IMR
     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]

  Interagency Interim National Research and Education Network (IINREN)
     An evolving operating network system.  Near term (1992-1996)
     research and development activities will provide for the smooth
     evolution of this networking infrastructure into the future
     gigabit NREN.
     [Source: HPCC]

  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, router.

  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]





User Glossary Working Group                                    [Page 24]

RFC 1392                   Internet Glossary                January 1993


  internet
     While an internet is a network, the term "internet" is usually
     used to refer to a collection of networks interconnected with
     routers.  See also: network.

  Internet
     (note the capital "I") The Internet is the largest internet in the
     world.  Is a three level hierarchy composed of backbone networks
     (e.g., NSFNET, MILNET), mid-level networks, and stub networks.
     The Internet is a multiprotocol internet.  See also: backbone,
     mid-level network, stub network, transit network, Internet
     Protocol, Corporation for Research and Educational Networks,
     National Science Foundation.

  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 technical body that oversees the development of the Internet
     suite of protocols.  It has two task forces: the IETF and the
     IRTF.  "IAB" previously stood for Internet Activities Board.  See
     also: Internet Engineering Task Force, Internet Research Task
     Force.

  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 "[email protected]".  See also:
     assigned numbers, STD.

  Internet Control Message Protocol (ICMP)
     ICMP is an extension to the Internet Protocol.  It allows for the
     generation of error messages, test packets and informational
     messages related to IP.  It is defined in STD 5, RFC 792.
     [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.




User Glossary Working Group                                    [Page 25]

RFC 1392                   Internet Glossary                January 1993


  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 are no longer active.  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
     organizations.

  internet number
     See: internet address

  Internet Protocol (IP)
     The Internet Protocol, defined in STD 5, 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, Request For Comments, TCP/IP Protocol Suite.

  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



User Glossary Working Group                                    [Page 26]

RFC 1392                   Internet Glossary                January 1993


     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 Force.
     [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 Mail.

  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 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 Government.
     [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.

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

  IP
     See: Internet Protocol





User Glossary Working Group                                    [Page 27]

RFC 1392                   Internet Glossary                January 1993


  IP address
     The 32-bit address defined by the Internet Protocol in STD 5, 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

  IPX
     See: Internetwork Packet eXchange

  IR
     See: Internet Registry

  IRC
     See: Internet Relay Chat

  IRSG
     See: Internet Research Steering Group

  IRTF
     See: Internet Research Task Force

  IS
     See: Intermediate System

  IS-IS
     See: Intermediate System-Intermediate System

  ISDN
     See: Integrated Services Digital Network

  ISO
     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.

  ISOC
     See: Internet Society

  ISODE
     See: ISO Development Environment





User Glossary Working Group                                    [Page 28]

RFC 1392                   Internet Glossary                January 1993


  JKREY
     Joyce K. Reynolds

  KA9Q
     A popular implementation of TCP/IP and associated protocols for
     amateur packet radio systems.  See also: TCP/IP Protocol Suite.
     [Source: RFC1208]

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

  Kermit
     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]

  Knowbot
     An experimental directory service.  See also: white pages, WHOIS,
     X.500.

  LAN
     See: Local Area Network

  layer
     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.

  listserv
     An automated mailing list distribution system originally designed
     for the Bitnet/EARN network.  See also: Bitnet, European Academic
     Research Network, mailing list.




User Glossary Working Group                                    [Page 29]

RFC 1392                   Internet Glossary                January 1993


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

  LLC
     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, 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 Control.

  Lurking
     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]

  MAC
     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]



User Glossary Working Group                                    [Page 30]

RFC 1392                   Internet Glossary                January 1993


  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]

  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



User Glossary Working Group                                    [Page 31]

RFC 1392                   Internet Glossary                January 1993


     should ALWAYS be sent to the list's "-request" address (e.g.,
     [email protected] for the IETF mailing list).  See
     also: Electronic Mail, mail exploder.

  MAN
     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]

  Martian
     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.
     [Source: RFC1208]

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

  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 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]

  MIB
     See: Management Information Base

  mid-level network
     Mid-level networks (a.k.a. regionals) make up the second level of



User Glossary Working Group                                    [Page 32]

RFC 1392                   Internet Glossary                January 1993


     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.

  MIME
     See: Multipurpose Internet Mail Extensions

  moderator
     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.

  MTU
     See: Maximum Transmission Unit

  MUD
     See: Multi-User Dungeon

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

  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.  It is
     defined in RFC 1341.  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 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: Telnet.
     [Source: LAQUEY]

  MX Record
     See: Mail Exchange Record

  NAK
     See: Negative Acknowledgment



User Glossary Working Group                                    [Page 33]

RFC 1392                   Internet Glossary                January 1993


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

  namespace
     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, is an essential part of
     academic and research communications.  It is a highspeed "network
     of networks" which is hierarchical in nature.  At the highest
     level, it is a backbone network currently comprising 16 nodes
     connected to a 45Mb/s facility which spans the continental United
     States.  Attached to that are mid-level networks and attached to
     the mid-levels are campus and local networks.  NSFNET also has
     connections out of the U.S. to Canada, Mexico, Europe, and the
     Pacific Rim.  The NSFNET is part of the Internet.

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

  netiquette
     A pun on "etiquette" referring to proper behavior on a network.

  Netnews
     See: Usenet

  network
     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.



User Glossary Working Group                                    [Page 34]

RFC 1392                   Internet Glossary                January 1993


     See also: Local Area Network, Metropolitan Area Network, Wide Area
     Network, internet.

  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,
     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
     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 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.  It is defined in STD 12, RFC 1119.  See



User Glossary Working Group                                    [Page 35]

RFC 1392                   Internet Glossary                January 1993


     also: Internet.
     [Source: NNSC]

  NFS
     See: Network File System

  NIC
     See: Network Information Center

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

  NIS
     See: Network Information Services

  NIST
     See: National Institute of Standards and Technology

  NNTP
     See: Network News Transfer Protocol

  NOC
     See: Network Operations Center

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

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

  NREN
     See: National Research and Education Network

  NSF
     See: National Science Foundation

  NSS
     See: Nodal Switching System

  NTP
     See: Network Time Protocol

  OCLC
     See: Online Computer Library Catalog



User Glossary Working Group                                    [Page 36]

RFC 1392                   Internet Glossary                January 1993


  octet
     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 Interior Gateway Protocol (OSPF)
     A link state, as opposed to distance vector, routing protocol.  It
     is an Internet standard IGP defined in RFC 1247.  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.

  OSI
     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]

  OSPF
     See: Open Shortest-Path First Interior Gateway Protocol

  packet
     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



User Glossary Working Group                                    [Page 37]

RFC 1392                   Internet Glossary                January 1993


     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,
     router.
     [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.

  PD
     Public Domain

  PDU
     See: Protocol Data Unit

  PEM
     See: Privacy Enhanced Mail

  PING
     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 1171, provides a
     method for transmitting packets over serial point-to-point links.
     See also: Serial Line IP.
     [Source: FYI4]

  POP
     See: Post Office Protocol and Point Of Presence

  port
     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.





User Glossary Working Group                                    [Page 38]

RFC 1392                   Internet Glossary                January 1993


  Post Office Protocol (POP)
     A protocol designed to allow single user hosts to read mail from a
     server.  There are three versions: POP, POP2, and POP3.  Latter
     versions are NOT compatible with earlier versions.  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.

  postmaster
     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]

  PPP
     See: Point-to-Point Protocol

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

  Prospero
     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.

  protocol
     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).





User Glossary Working Group                                    [Page 39]

RFC 1392                   Internet Glossary                January 1993


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

  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]

  PSN
     See: Packet Switch Node.

  PTT
     See: Postal, Telegraph and Telephone

  queue
     A backup of packets awaiting processing.

  RARE
     See: Reseaux Associes pour la Recherche Europeenne

  RARP
     See: Reverse Address Resolution Protocol

  RBOC
     Regional Bell Operating Company

  RCP
     See: Remote copy program

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

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





User Glossary Working Group                                    [Page 40]

RFC 1392                   Internet Glossary                January 1993


  recursive
     See: recursive

  regional
     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.
     [Source: RFC1208]

  repeater
     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: For
     Your Information, STD.

  Reseaux Associes pour la Recherche Europeenne (RARE)
     European association of research networks.
     [Source: RFC1208]

  Reseaux IP Europeenne (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.



User Glossary Working Group                                    [Page 41]

RFC 1392                   Internet Glossary                January 1993


  RFC
     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 (STD 11, RFC 822).
     822 format was previously known as 733 format.  See also:
     Electronic Mail.
     [Source: COMER]

  RIP
     See: Routing Information Protocol

  RIPE
     See: Reseaux IP Europeenne

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

  route
     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.

  routed
     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.

  router
     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.

  routing
     The process of selecting the correct interface and next hop for a
     packet being forwarded.  See also: hop, router, Exterior Gateway
     Protocol, Interior Gateway Protocol.

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




User Glossary Working Group                                    [Page 42]

RFC 1392                   Internet Glossary                January 1993


  Routing Information Protocol (RIP)
     A distance vector, as opposed to link state, routing protocol.  It
     is an Internet standard IGP defined in STD 34, RFC 1058 (updated
     by RFC 1388).  See also: Interior Gateway Protocol, Open Shortest
     Path First....

  RPC
     See: Remote Procedure Call

  RTFM
     See: Read the F*cking Manual

  RTT
     See: Round-Trip Time

  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.  See also: Point-to-Point Protocol.

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

  SIG
     Special Interest Group

  signature
     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, Usenet.

  Simple Mail Transfer Protocol (SMTP)
     A protocol, defined in STD 10, RFC 821, used to transfer
     electronic mail between computers.  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, defined in STD 15, RFC 1157,
     developed to manage nodes on an IP network.  It is currently
     possible to manage wiring hubs, toasters, jukeboxes, etc.  See
     also: Management Information Base.

  SLIP
     See: Serial Line IP




User Glossary Working Group                                    [Page 43]

RFC 1392                   Internet Glossary                January 1993


  SMDS
     See: Switched Multimegabit Data Service

  SMI
     See: Structure of Management Information

  SMTP
     See: Simple Mail Transfer Protocol

  SNA
     See: Systems Network Architecture

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

  SNMP
     See: Simple Network Management Protocol

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

  stream-oriented
     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.  This protocol is defined in STD 16,
     RFC 1155.  See also: Management Information Base.
     [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.

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



User Glossary Working Group                                    [Page 44]

RFC 1392                   Internet Glossary                January 1993


     [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

  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]

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

  T1
     An AT&T term for a digital carrier facility used to transmit a
     DS-1 formatted digital signal at 1.544 megabits per second.

  T3
     A term for a digital carrier facility used to transmit a DS-3
     formatted digital signal at 44.746 megabits per second.
     [Source: FYI4]

  TAC
     See: Terminal Access Controller (TAC)

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

  TCP
     See: Transmission Control Protocol

  TCP/IP Protocol Suite
     Transmission Control Protocol over Internet Protocol.  This is a



User Glossary Working Group                                    [Page 45]

RFC 1392                   Internet Glossary                January 1993


     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.

  TELENET
     A public packet switched network using the CCITT X.25 protocols.
     It should not be confused with Telnet.

  Telnet
     Telnet is the Internet standard protocol for remote terminal
     connection service.  It is defined in STD 8, RFC 854 and extended
     with options by many other RFCs.

  Terminal Access Controller (TAC)
     A device which connects terminals to the Internet, usually using
     dialup modem connections and the TACACS protocol.

  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]

  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]

  TLA
     See: Three Letter Acronym

  TN3270
     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
     terminal.
     [Source: BIG-LAN]





User Glossary Working Group                                    [Page 46]

RFC 1392                   Internet Glossary                January 1993


  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.

  topology
     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]

  transceiver
     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 STD 7,
     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.  See RFC 1135.

  TTFN
     Ta-Ta For Now

  TTL
     See: Time to Live

  tunnelling
     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



User Glossary Working Group                                    [Page 47]

RFC 1392                   Internet Glossary                January 1993


     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.

  UDP
     See: User Datagram Protocol

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

  UNIX-to-UNIX CoPy (UUCP)
     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]

  Usenet
     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 STD 6,
     RFC 768.  It is a connectionless protocol which adds a level of
     reliability and multiplexing to IP.  See also: connectionless,
     Transmission Control Protocol.

  UTC
     See: Universal Time Coordinated



User Glossary Working Group                                    [Page 48]

RFC 1392                   Internet Glossary                January 1993


  UUCP
     See: UNIX-to-UNIX CoPy

  virtual circuit
     A network service which provides connection-oriented service
     regardless of the underlying network structure.  See also:
     connection-oriented.

  virus
     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.

  W3
     See: World Wide Web

  WAIS
     See: Wide Area Information Servers

  WAN
     See: Wide area network

  WG
     Working Group

  white pages
     The Internet supports several databases that contain basic
     information about users, such as email 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, WHOIS, X.500.

  WHOIS
     An Internet program which allows users to query a database of
     people and other Internet entities, such as domains, networks, and
     hosts, kept at the DDN NIC.  The information for people shows a
     person's company name, address, phone number and email address.
     See also: Defense Data Network Network ..., white pages, Knowbot,
     X.500.
     [Source: FYI4]

  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,



User Glossary Working Group                                    [Page 49]

RFC 1392                   Internet Glossary                January 1993


     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.

  World Wide Web (WWW or 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.

  worm
     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.

  WRT
     With Respect To

  WWW
     See: World Wide Web

  WYSIWYG
     What You See is What You Get

  X
     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.

  X.25
     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.

  X.400
     The CCITT and ISO standard for electronic mail.  It is widely used
     in Europe and Canada.





User Glossary Working Group                                    [Page 50]

RFC 1392                   Internet Glossary                January 1993


  X.500
     The CCITT and ISO standard for electronic directory services.  See
     also: white pages, Knowbot, WHOIS.

  XDR
     See: eXternal Data Representation

  Xerox Network System (XNS)
     A network developed by Xerox corporation.  Implementations exist
     for both 4.3BSD derived systems, as well as the Xerox Star
     computers.

  XNS
     See: Xerox Network System

  Yellow Pages (YP)
     A service used by UNIX administrators to manage databases
     distributed across a network.

  YP
     See: Yellow Pages

  zone
     A logical group of network devices (AppleTalk).



























User Glossary Working Group                                    [Page 51]

RFC 1392                   Internet Glossary                January 1993


References

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

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

  FYI4    Malkin, G., and A. Marine, "FYI on Questions and Answers:
          Answers to Commonly asked "New Internet User" Questions", FYI
          4, RFC 1325, 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, C., "Analyzing Sun Networks", Van Nostrand Reinhold,
          New York, NY, 1992.

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

  LAQUEY  LaQuey, T. (with J. Ryer), "The Internet Companion: A
          Beginner's Guide to Global Networking", Addison-Wesley,
          Reading, MA, 1992.

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

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

  STD1    Postel, J., "IAB Official Protocol Standards", STD 1, RFC
          1360, Internet Architecture Board, September 1992.

  STD2    Reynolds, J., and J. Postel, "Assigned Numbers", STD 2, RFC
          1340, USC/Information Sciences Institute, July 1992.

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

  ZEN     Kehoe, B., "Zen and the Art of the Internet", February 1992.





User Glossary Working Group                                    [Page 52]

RFC 1392                   Internet Glossary                January 1993


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, Privacy Enhanced
  Mail (PEM), Trojan Horse, virus, and worm.


Authors' Addresses

  Gary Scott Malkin
  Xylogics, Inc.
  53 Third Avenue
  Burlington, MA 01803

  Phone:  (617) 272-8140
  EMail:  [email protected]


  Tracy LaQuey Parker
  University of Texas at Austin
  Computation Center
  Austin, TX 78712

  Phone: (512) 471-2444
  EMail: [email protected]























User Glossary Working Group                                    [Page 53]