Tech-invite3GPPspaceIETFspace
9796959493929190898887868584838281807978777675747372717069686766656463626160595857565554535251504948474645444342414039383736353433323130292827262524232221201918171615141312111009080706050403020100
in Index   Prev   Next

RFC 1983

Internet Users' Glossary

Pages: 62
FYI 18
Obsoletes:  1392

ToP   noToC   RFC1983 - Page 1
Network Working Group                                  G. Malkin, Editor
Request for Comments: 1983                                      Xylogics
FYI: 18                                                      August 1996
Obsoletes: 1392
Category: Informational


                        Internet Users' Glossary


Status of this Memo

   This memo provides information for the Internet community.  This memo
   does not specify an Internet standard of any kind.  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.  I would
   especially like to thank Ryan Moats/InterNIC for his careful review
   and many contributions to this document.


Table of Contents

   non-letter  . .  2      I . . . . . . . 26      R . . . . . . . 46
   A . . . . . . .  2      J . . . . . . . 33      S . . . . . . . 49
   B . . . . . . .  7      K . . . . . . . 33      T . . . . . . . 52
   C . . . . . . . 10      L . . . . . . . 33      U . . . . . . . 55
   D . . . . . . . 14      M . . . . . . . 35      V . . . . . . . 57
   E . . . . . . . 18      N . . . . . . . 39      W . . . . . . . 57
   F . . . . . . . 20      O . . . . . . . 42      X . . . . . . . 59
   G . . . . . . . 22      P . . . . . . . 43      Y . . . . . . . 60
   H . . . . . . . 23      Q . . . . . . . 46      Z . . . . . . . 60

   References  . . . . . . . . . . . . . . . . . . . . . . . . . . 61
   Security Considerations . . . . . . . . . . . . . . . . . . . . 62
   Editor's Address  . . . . . . . . . . . . . . . . . . . . . . . 62
ToP   noToC   RFC1983 - Page 2
Glossary

   10Base2
      A physical layer communications specification for 10Mbps, baseband
      data transmission over a coaxial cable (Thinnet) with a maximum
      cable segment length of 200 meters.

   10Base5
      A physical layer communications specification for 10Mbps, baseband
      data transmission over a coaxial cable (Thicknet) with a maximum
      cable segment length of 500 meters.

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

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

   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.
ToP   noToC   RFC1983 - Page 3
   Acceptable Use Policy (AUP)
      Many transit networks have policies which restrict the use to
      which the network may be put.  For example, some networks may only
      be used for non-commercial purposes.  Some AUPs limit the type of
      material which can be made available to the public (e.g.,
      pornographic material).  Enforcement of AUPs varies with the
      network.  See also: netiquette.

   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

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

   address mask
      A bit mask used to identify which bits in an IP address correspond
      to the network and subnet portions of the address.  This mask is
      often referred to as the subnet mask because the network portion
      of the address (i.e., the network mask) can be determined by the
      encoding inherent in an IP address.  See also: Classless Inter-
      domain Routing.
ToP   noToC   RFC1983 - Page 4
   address resolution
      Conversion of a network-layer address (e.g. IP address) into the
      corresponding physical address (e.g., MAC address).  See also: IP
      address, MAC address.

   Address Resolution Protocol (ARP)
      Used to dynamically discover the low level physical network
      hardware address that corresponds to the high level IP address for
      a given host.  ARP is limited to physical network systems that
      support broadcast packets that can be heard by all hosts on the
      network.  See also: proxy ARP, Reverse Address Resolution
      Protocol.

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

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

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

   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
ToP   noToC   RFC1983 - Page 5
      (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, World Wide Web.

   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
      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]
ToP   noToC   RFC1983 - Page 6
   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.  For example, an anonymous FTP archive site provides
      access to arcived material via the FTP protocol.  WWW servers can
      also serve as archive sites.  See also: anonymous FTP, archie,
      Gopher, Prospero, Wide Area Information Servers, World Wide Web.

   ARP
      See: Address Resolution Protocol

   ARPA
      See: 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
      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]
ToP   noToC   RFC1983 - Page 7
   Asynchronous Transfer Mode (ATM)
      A standard which defines high-load, high-speed (1.544Mbps through
      1.2Gbps), fixed-size packet (cell) switching with dynamic
      bandwidth allocation.  ATM is also known as "fast packet."

   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
      communication channel is available at any given time.  Ethernet is
      an example of a baseband network.  See also: broadband, Ethernet.
      [Source: NNSC]
ToP   noToC   RFC1983 - Page 8
   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

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

   BER
      See: Basic Encoding Rules

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

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

   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
ToP   noToC   RFC1983 - Page 9
      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]

   binary
      11001001

   BIND
      See: Berkeley Internet Name Daemon

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

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

   Border Gateway Protocol (BGP)
      The Border Gateway Protocol is an exterior gateway protocol
      defined in RFC 1771.  It's design is based on experience gained
      with EGP, as defined in RFC 904, and EGP usage in the NSFNET
      Backbone, as described in RFCs 1092 and 1093.  See also: Exterior
      Gateway 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.
ToP   noToC   RFC1983 - Page 10
   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.

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

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

   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.
ToP   noToC   RFC1983 - Page 11
   CCIRN
      See: Coordinating Committee for Intercontinental Research Networks

   CCITT
      See: Comite Consultatif International de Telegraphique et
      Telephonique

   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.  See
      also: Cyclic Redundancy Check.
      [Source: NNSC]

   CIDR
      See: Classless Inter-domain Routing

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

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

   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]
ToP   noToC   RFC1983 - Page 12
   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 (no, they are not acronyms) to promote the creation of, and
      access to, information resources in networked environments in
      order to enrich scholarship and enhance intellectual productivity.

   Comite Consultatif International de Telegraphique et Telephonique (
      CCITT)
      This organization is now part of the International
      Telecommunications Union and is responsible for making technical
      recommendations about telephone and data communications systems.
      Every four years CCITT holds plenary sessions where they adopt new
      standards; the most recent was in 1992.  Recently, the ITU
      reorganized and CCITT was renamed the ITU-TSS.  See also:
      International Telecommunications Union - Telecommunications
      Standards Sector.

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

   congestion
      Congestion occurs when the offered load exceeds the capacity of a
      data communication path.
ToP   noToC   RFC1983 - Page 13
   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
      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
ToP   noToC   RFC1983 - Page 14
   CREN
      See: Corporation for Research and Educational Networking

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

   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.  See also: checksum.
      [Source: MALAMUD]

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

   DARPA
      Defense Advanced Research Projects Agency
      See: Advanced Research Projects Agency

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

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

   datagram
      A self-contained, independent entity of data carrying sufficient
      information to be routed from the source to the destination
ToP   noToC   RFC1983 - Page 15
      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 Data Network (DDN)
      A global communications network serving the US Department of
      Defense composed of MILNET, other portions of the Internet, and
      classified networks which are not part of the Internet.  The DDN
      is used to connect military installations and is managed by the
      Defense Information Systems Agency.  See also: Defense Information
      Systems Agency.

   Defense Data Network Network Information Center (DDN NIC)
      Previously called "The NIC", the DDN NIC's primary responsibility
      was the assignment of Internet network addresses and Autonomous
      System numbers, the administration of the root domain, and
      providing information and support services to the Internet for the
      DDN.  Since the creation of the InterNIC, the DDN NIC performs
      these functions only for the DDN.  See also: Autonomous System,
      network address, Internet Registry, InterNIC, Network Information
      Center, Request For Comments.
ToP   noToC   RFC1983 - Page 16
   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 phone line (analog or ISDN).  See also:
      Integrated Services Digital Network.

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

   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]
ToP   noToC   RFC1983 - Page 17
   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.  The country domain names are
      based on ISO 3166.  For example, .US (United States), .UK (United
      Kingdom), .AU (Australia).  See also: Fully Qualified Domain Name,
      Mail Exchange Record.

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

   DSA
      See: Directory System Agent

   DTE
      Data Terminal Equipment

   DUA
      See: Directory User Agent
ToP   noToC   RFC1983 - Page 18
   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]

   E1
      The basic building block for European multi-megabit data rates,
      with a bandwidth of 2.048Mbps.  See also: T1.

   E3
      A European standard for transmitting data at 57.344Mbps.  See
      also: T3.

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

   EBCDIC
      See: Extended Binary Coded Decimal Interchange Code

   Ebone
      A pan-European backbone service.

   EFF
      See: Electronic Frontier Foundation

   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.
      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
ToP   noToC   RFC1983 - Page 19
      is "gmalkin@xylogics.com".  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.  For example, in Internet terminology, a packet would
      contain a header from the physical layer, followed by a header
      from the datalink layer (e.g.  Ethernet), followed by a header
      from the network layer (IP), followed by a header from the
      transport layer (e.g. TCP), followed by the application protocol
      data.
      [Source: RFC1208]

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

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

   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.  See also: broadcast storm.
      [Source: COMER]

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

   Exterior Gateway Protocol (EGP)
      A protocol which distributes routing information to the routers
      which connect autonomous systems.  The term "gateway" is
      historical, as "router" is currently the preferred term.  There is
      also a routing protocol called EGP defined in RFC 904.  See also:
ToP   noToC   RFC1983 - Page 20
      Autonomous System, Border Gateway Protocol, Interior Gateway
      Protocol.

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

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

   Fiber Distributed Data Interface (FDDI)
      A high-speed (100Mb/s) LAN standard.  The underlying medium is
      fiber optics, and the topology is a dual-attached, counter-
      rotating token ring.  See also: Local Area Network, token ring.
      [Source: RFC1208]

   file transfer
      The copying of a file from one computer to another over a computer
      network.  See also: File Transfer Protocol, Kermit, Gopher, World
      Wide Web.
ToP   noToC   RFC1983 - Page 21
   File Transfer Protocol (FTP)
      A protocol which allows a user on one host to access, and transfer
      files to and from, another host over a network.  Also, FTP is
      usually the name of the program the user invokes to execute the
      protocol.  See also: anonymous FTP.

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

   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 pend