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<H2>Linux System Administrator's Survival Guide lsgxg.htm</H2>



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<FONT SIZE=6 COLOR="#FF0000"><B>Appendix G</B></FONT></CENTER></H1>



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<FONT SIZE=6 COLOR="#FF0000"><B>Glossary</B></FONT></CENTER></H2>



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<P><B>10Base2</B>  An Ethernet term meaning a maximum transfer rate of 10 Megabits per second, which uses baseband signaling, with a contiguous cable segment length of 100 meters and a maximum of two segments.



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<P><B>10Base5</B>  An Ethernet term meaning a maximum transfer rate of 10 Megabits per second, which uses baseband signaling, with five continuous segments not exceeding 100 meters per segment.



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<P><B>1OBaseT</B>  An Ethernet term meaning a maximum transfer rate of 10 Megabits per second, which uses baseband signaling and twisted pair cabling.



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<P><B>Acknowledgment (ACK)</B>  A positive response returned from a receiver to the sender indicating success. TCP uses acknowledgments to indicate the successful reception of a packet.



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<P><B>Address</B>  A memory location in a particular machine's RAM; a numeric identifier or symbolic name that specifies the location of a particular machine or device on a network; and a means of identifying a complete network, subnetwork, or a node within a network.



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<P><B>Address Mask (also called the subnet mask)</B>  A set of rules for omitting parts of a complete IP address in order to reach the target destination without using a broadcast message. The mask can, for example, indicate a subnetwork portion of a larger network. In TCP/IP, the address mask uses the 32-bit IP address.



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<P><B>Address Resolution</B>  Mapping of an IP address to a machine's physical address. TCP/IP uses the Address Resolution Protocol (ARP) for this function.



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<P><B>Address Resolution Protocol (ARP)</B>  See Address Resolution.



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<P><B>Address Space</B>  A range of memory addresses available to an application program.



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<P><B>Agent</B>  In TCP/IP, a agent is an SNMP process that responds to get and set requests. Agents can also send trap messages.



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<P><B>American National Standards Institute (ANSI)</B>  The body responsible for setting standards in the U.S.



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<P><B>Application Programming Interface (API)</B>  A set of routines that are available to developers and applications to provide specific services used by the system, usually specific to the application's purpose. They act as access methods into the application.



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<P><B>Application Layer</B>  The highest layer in the OSF model. It establishes communications rights and can initiate a connection between two applications.



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<P><B>ASCII (American National Standard Code for Information </B><B>Interchange)</B>  An 8-bit character set defining alphanumeric characters.



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<P><B>Asynchronous</B>  Communications without a regular time basis allowing transmission at unequal rates.



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<P><B>Bandwidth</B>  The range of frequencies transmitted on a channel, or the difference between the highest and lowest frequencies transmitted across a channel.



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<P><B>Baseband</B>  A type of channel in which data transmission is carried across only one communications channel, supporting only one signal transmission at a time. Ethernet is a baseband system.



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<P><B>Baud</B>  The number of times a signal changes state in one second.



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<P><B>Berkeley Software Distribution (BSD)</B>  A version of the UNIX operating system that first included TCP/IP support. The UNIX operating systems that included TCP/IP are referred to as 4.2BSD or 4.3BSD.



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<P><B>Bit rate</B>  The rate that bits are transmitted, usually expressed in seconds.



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<P><B>Block Mode</B>  A string of data recorded or transmitted as a unit. Block mode transmission is usually used for high-speed transmissions and in large, high-speed networks.



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<P><B>Broadcast</B>  The simultaneous transmission of the same data to all nodes connected to the network.



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<P><B>Buffer</B>  A memory area used for handling input and output.



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<P><B>Cache</B>  A memory location that keeps frequently requested material ready. Usually a cache is faster than a storage device. It is used to speed data and instruction transfer.



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<P><B>Client</B>  A program that tries to connect to another program (usually on another machine) called a &quot;server&quot;. The client &quot;calls&quot; the server. The server &quot;listens&quot; for calls.



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<P><B>Client-Server Architecture</B>  A catchall term used to refer to a distributed environment in which one program can initiate a session and another program answers its requests. The origin of client-server designs is closely allied with the TCP/IP protocol suite.



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<P><B>Connection</B>  A link between two or more processes, applications, machines, networks, and so on. Connections may be logical, physical, or both.



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<P><B>Connectionless</B>  A type of network service that does not send acknowledgments upon receipt of data to the sender. UDP is a connectionless protocol.



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<P><B>Connection-Oriented</B>  A type of network service in which the transport layer protocol sends acknowledgments to the sender regarding incoming data. This type of service usually provides for retransmission of corrupted or lost data.



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<P><B>Cyclic Redundancy Check (CRC)</B>  A mathematical function performed on the contents of an entity that is then included to allow a receiving system to recalculate the value and compare to the original. If the values are different, corruption of the contents has occurred.



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<P><B>Daemon</B>  A UNIX process that operates continuously and unattended to perform a service. TCP/IP uses several daemons to establish communications processes and provide server facilities.



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<P><B>DARPA (Defense Advanced Research Project Agency)</B>  The governmental body that created the DARPANET for widespread communications. DARPANET eventually became the Internet.



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<P><B>Datagram</B>  A basic unit of data used with TCP/IP.



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<P><B>Data Circuit-Terminating Equipment (DCE)</B>  Required equipment to attach Data Terminal Equipment (DTE) to a network or serial line. A modem is a DCE device. Also called Data Communications Equipment and Data Circuit Equipment.



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<P><B>Data Encryption Standard (DES)</B>  An encryption standard officially sanctioned in the U.S.



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<P><B>Data Link</B>  The part of a node controlled by a data link protocol. It is the logical connection between two nodes.



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<P><B>Data Link Protocol</B>  A method of handling the establishment, maintenance, and termination of a logical link between nodes. Ethernet is a DLP.



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<P><B>Data Terminal Equipment (DTE)</B>  The source or destination of data, usually attached to a network by DEC devices. A terminal or computer acting as a node on a network is usually a DTE device.



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<P><B>Defense Communications Agency (DCA)</B>  The governmental agency responsible for the Defense Data Network (DDN).



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<P><B>Defense Data Network (DDN)</B>  Refers to military networks such as MILNET, ARPANET, and the communications protocols (including TCP/IP) that they employ.



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<P><B>Destination Address</B>  The destination device's address.



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<P><B>Distributed Processing</B>  When a process is spread over two or more devices, it is distributed. It is usually used to spread CPU loads among a network of machines.



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<P><B>Domain Name System (DNS)</B>  A service that converts symbolic node names to IP addresses. DNS is frequently used with TCP/IP. DNS uses a distributed database.



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<P><B>Dotted Decimal Notation</B>  A representation of IP addresses. Also called &quot;dotted quad notation&quot; because it uses four sets of numbers separated by decimals (such as 255.255.255.255).



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<P><B>Double-Byte Character Set</B>  A character set in which alphanumeric characters are represented by two bytes, instead of one bytes as with ASCII. Double-byte characters are often necessary for oriental languages that have more than 255 symbols.



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<P><B>Dumb Terminal</B>  A terminal with no significant processing capability of its own, usually with no graphics capabilities beyond the ASCII set.



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<P><B>Emulation</B>  A program that simulates another device. For example, a 3270 emulator emulates an IBM 3270 terminal, sending the same codes as the real device would.



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<P><B>Ethernet</B>  A data link level protocol comprising the OSI model's bottom two layers. It is a broadcast networking technology that can use several different physical media, including twisted pair cable and coaxial cable. TCP/IP is commonly used with Ethernet networks.



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<P><B>Ethernet Address</B>  A 48-bit address commonly referred to as a &quot;physical&quot; or &quot;hard&quot; address, which uniquely identifies the Ethernet Network Interface Card (NIC) and hence the device the card resides in.



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<P><B>Ethernet Meltdown</B>  A slang term for a situation in which an Ethernet network becomes saturated. The condition usually persists only for a short time and is usually caused by a misrouted or invalid packet.



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<P><B>Extended Binary Coded Decimal Interchange Code (EBCDIC)</B>  An alternative to ASCII used extensively in IBM machinery. Some other vendors use it for mainframes. EBCDIC and ASCII are not compatible but are easy to convert between.



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<P><B>File Server</B>  A process that provides access to a file from remote devices.



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<P><B>File Transfer Protocol (FTP)</B>  A TCP/IP application used for transferring files from one system to another.



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<P><B>Frame Relay</B>  A network switching mechanism for routing frames as quickly as possible.



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<P><B>Gateway</B>  In Internet terms, a gateway is a device that routes datagrams. More recently, the term &quot;gateway&quot; has been used to refer to any networking device that translates protocols of one type network into those of another network.



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<P><B>Gigabyte</B>  One billion bytes corresponding to decimal 1,073,741,824 (as a &quot;kilobyte&quot; is 1,024 decimal).



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<P><B>Hardware Address</B>  The low-level address associated with each device on a network, usually corresponding to the unique identifier of the network interface card (NIC). Ethernet addresses are 48 bits.



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<P><B>Institute of Electrical and Electronic Engineers (IEEE)</B>  A professional organization for engineers that also proposes and approves standards.



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<P><B>Integrated Service Digital Network (ISDN)</B>  A set of standards for integrating multiple services (voice, data, video, and so on).



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<P><B>International Organization for Standardization (ISO)</B>  An international body composed of individual country's standards groups that focuses upon international standards.



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<P><B>Internet</B>  A collection of networks connected together that span the world, which uses the NFSNET as its backbone. The Internet is the specific term for a more general internetwork or collection of networks.