Guide To Networks Ch4 Terms

Front 1

address resource record

Back 1

A type of DNS data record that maps the IP address of an Internet-connected device to its domain name.

Front 2

alias

Back 2

A nickname for a node’s host name. Aliases can be specified in a local host file.

Front 3

anycast address

Back 3

A type of address specified in IPv6 that represents a group of interfaces, any one of which (and usually the first available of which) can accept a transmission. At this time, anycast addresses are not designed to be assigned to hosts, such as servers orworkstations, but rather to routers.

Front 4

APIPA

Back 4

(Automatic Private IP Addressing) A service available on computers running the Windows 98, Me, 2000, XP, Vista, Server 2003, or Server 2008 operating system that automatically assigns the computer’s network interface an IP address from the range of 169.254.0.0 to 169.254.255.255 if an IP address hasn’t been assigned to that interface.

Front 5

ARP

Back 5

(Address Resolution Protocol) A core protocol in the TCP/IP suite that belongs in the Network layer of the OSI model. ARP obtains the MAC (physical) address of a host, or node, and then creates a local database that maps the MAC address to the host’s IP (logical) address.

Front 6

ARP table

Back 6

A database of records that maps MAC addresses to IP addresses. The ARP table is stored on a computer’s hard disk where it is used by the ARP utility to supply the MAC addresses of network nodes, given their IP addresses.

Front 7

BOOTP

Back 7

(Bootstrap Protocol)

Front 8

country code TLD

Back 8

A top-level domain that corresponds to a country. For example, the country code TLD for Canada is .ca, and the country code TLD for Japan is .jp.

Front 9

DDNS

Back 9

(Dynamic DNS) A method of dynamically updating DNS records for a host. DDNS client computers are configured to notify a service provider when their IP addresses change, then the service provider propagates the DNS record change across the Internet automatically.

Front 10

DHCP

Back 10

(Dynamic Host Configuration Protocol) An Application layer protocol in the TCP/IP suite that manages the dynamic distribution of IP addresses on a network. Using DHCP to assign IP addresses can nearly eliminate duplicate-addressing problems.

Front 11

diskless workstation

Back 11

A workstation that doesn’t contain a hard disk, but instead relies on a small amount of read-only memory to connect to a network and to pick up its system files.

Front 12

DNS

Back 12

(Domain Name System or Domain Name Service) A hierarchical way of tracking domain names and their addresses, devised in the mid-1980s. The DNS database does not rely on one file or even one server, but rather is distributed over several key computers across the Internet to prevent catastrophic failure if one or a few computers go down. DNS is a TCP/IP service that belongs to the Application layer of the OSI model.

Front 13

domain

Back 13

A group of computers that belong to the same organization and have part of their IP addresses in common.

Front 14

domain name

Back 14

The symbolic name that identifies a domain. Usually, a domain name is associated with a company or other type of organization, such as a university or military unit.

Front 15

dotted decimal notation

Back 15

The shorthand convention used to represent IPv4 addresses and make them more easily readable by humans. In dotted decimal notation, a decimal number between 0 and 255 represents each binary octet. A period, or dot, separates each decimal.

Front 16

dynamic

Back 16

ARP table entry A record in an ARP table that is created when a client makes an ARP request that cannot be satisfied by data already in the ARP table.

Front 17

dynamic IP address

Back 17

An IP address that is assigned to a device upon request and may change when the DHCP lease expires or is terminated. BOOTP and DHCP are two ways of assigning dynamic IP addresses.

Front 18

Dynamic Ports

Back 18

TCP/IP ports in the range of 49,152 through 65,535, which are open for use without requiring administrative privileges on a host or approval from IANA.

Front 19

echo reply

Back 19

The response signal sent by a device after another device pings it.

Front 20

echo request

Back 20

The request for a response generated when one device pings another device.

Front 21

Format Prefix A

Back 21

variable-length field at the beginning of an IPv6 address that indicates what type of address it is (for example, unicast, anycast, or multicast).

Front 22

FTP

Back 22

(File Transfer Protocol) An Application layer protocol used to send and receive files via TCP/IP.

Front 23

fully qualified host name

Back 23

A host name plus domain name. For example, a host belonging to the loc.gov domain might be called Jasmine, making its fully qualified host name Jasmine.loc.gov.

Front 24

hop

Back 24

A term used to describe each trip a unit of data takes from one connectivity device to another. Typically, hop is used in the context of router-to-router communications. host file A text file that associates TCP/IP host names with IP addresses.

Front 25

host name

Back 25

A symbolic name that describes a TCP/IP device.

Front 26

hosts

Back 26

The name of the host file used on UNIX, Linux, and Windows systems. On a UNIXor Linux-based computer, hosts is found in the /etc directory. On a Windows-based computer, it is found in the %systemroot%\system32\drivers\etc folder.

Front 27

ICMP

Back 27

(Internet Control Message Protocol) A core protocol in the TCP/IP suite that notifies the sender that something has gone wrong in the transmission process and that packets were not delivered.

Front 28

ifconfig

Back 28

A TCP/IP configuration and management utility used with UNIX and Linux systems.

Front 29

IGMP

Back 29

(Internet Group Management Protocol or Internet Group Multicast Protocol) A TCP/IP protocol used to manage multicast transmissions. Routers use IGMP to determine which nodes belong to a multicast group, and nodes use IGMP to join or leave a multicast group.

Front 30

internetwork

Back 30

To traverse more than one LAN segment and more than one type of network through a router.

Front 31

IP datagram

Back 31

The IP portion of a TCP/IP frame that acts as an envelope for data, holding information necessary for routers to transfer data between subnets.

Front 32

ipconfig

Back 32

The utility used to display TCP/IP addressing and domain name information in the Windows NT, Windows 2000, Windows XP, and Windows Vista client operating systems.

Front 33

IPv4

Back 33

(IP version 4) The current standard for IP addressing that specifies 32-bit addresses composed of four octets.

Front 34

IPv4LL

Back 34

(IP version 4 Link Local) A protocol that manages automatic address assignment among locally connected nodes. IPv4LL is part of the Zeroconf group of protocols.

Front 35

IPv6

Back 35

(IP version 6) A newer standard for IP addressing that will replace the current IPv4 (IP version 4). Most notably, IPv6 uses a newer, more efficient header in its packets and allows for 128-bit source and destination IP addresses. The use of longer addresses will allow for many more IP addresses to be in circulation.

Front 36

label

Back 36

A character string that represents a domain (either top-level, second-level, or thirdlevel).

Front 37

lease

Back 37

The agreement between a DHCP server and client on how long the client can use a DHCP-assigned IP address. DHCP services can be configured to provide lease terms equal to any amount of time.

Front 38

loopback address

Back 38

An IP address reserved for communicating from a node to itself (used mostly for troubleshooting purposes). The IPv4 loopback address is always cited as 127.0.0.1, although in fact, transmitting to any IP address whose first octet is 127 will contact the originating device. In IPv6, the loopback address is represented as ::1.

Front 39

loopback test

Back 39

An attempt to contact one’s own machine for troubleshooting purposes. In TCP/IP-based networking, a loopback test can be performed by communicating with an IPv4 address that begins with an octet of 127. Usually, this means pinging the address 127.0.0.1.

Front 40

multicast address

Back 40

A type of address in the IPv6 that represents multiple interfaces, often on multiple nodes. An IPv6 multicast address begins with the following hexadecimal field: FF0x, where x is a character that identifies the address’s group scope.

Front 41

multicasting

Back 41

A means of transmission in which one device sends data to a specific group of devices (not necessarily the entire network segment) in a point-to-multipoint fashion.

Front 42

name server

Back 42

A server that contains a database of TCP/IP host names and their associated IP addresses. A name server supplies a resolver with the requested information. If it cannot resolve the IP address, the query passes to a higher-level name server.

Front 43

namespace

Back 43

The database of Internet IP addresses and their associated names distributed over DNS name servers worldwide.

Front 44

network class

Back 44

A classification for TCP/IP-based networks that pertains to the network’s potential size and is indicated by an IP address’s network ID and subnet mask. Network Classes A, B, and C are commonly used by clients on LANs; network Classes D and E are reserved for special purposes.

Front 45

network ID

Back 45

The portion of an IP address common to all nodes on the same network or subnet.

Front 46

newsgroup

Back 46

An Internet-based forum for exchanging messages on a particular topic. Newsgroups rely on NNTP for the collection and dissemination of messages.

Front 47

NNTP

Back 47

(Network News Transfer Protocol or Network News Transport Protocol) An Application layer protocol in the TCP/IP suite that facilitates the exchange of newsgroup messages, or articles, between multiple servers and users.

Front 48

NTP

Back 48

(Network Time Protocol) A simple Application layer protocol in the TCP/IP suite used to synchronize the clocks of computers on a network. NTP depends on UDP for Transport layer services.

Front 49

octet

Back 49

One of the four bytes that are separated by periods and together make up an IPv4 address.

Front 50

ping

Back 50

To send an echo request signal from one node on a TCP/IP-based network to another, using the PING utility. See also PING.

Front 51

PING

Back 51

(Packet Internet Groper) A TCP/IP troubleshooting utility that can verify that TCP/IP is installed, bound to the NIC, configured correctly, and communicating with the network. PING uses ICMP to send echo request and echo reply messages that determine the validity of an IP address.

Front 52

port number

Back 52

The address on a host where an application makes itself available to incoming data.

Front 53

RARP

Back 53

(Reverse Address Resolution Protocol) A core protocol in the TCP/IP suite that belongs in the Network layer of the OSI model. RARP relies on a RARP table to associate the IP (logical) address of a node with its MAC (physical) address. RARP can be used to supply IP addresses to diskless workstations.

Front 54

Registered Ports

Back 54

The TCP/IP ports in the range of 1024 to 49,151. These ports are accessible to network users and processes that do not have special administrative privileges. Default assignments of these ports must be registered with IANA.

Front 55

release

Back 55

The act of terminating a DHCP lease.

Front 56

Rendezvous

Back 56

Apple Computer’s implementation of the Zeroconf group of protocols.

Front 57

resolver

Back 57

Any host on the Internet that needs to look up domain name information.

Front 58

resource record

Back 58

The element of a DNS database stored on a name server that contains information about TCP/IP host names and their addresses.

Front 59

root server

Back 59

A DNS server maintained by ICANN and IANA that is an authority on how to contact the top-level domains, such as those ending with .com, .edu, .net, .us, and so on. ICANN oversees the operation of 13 root servers around the world.

Front 60

routable

Back 60

The protocols that can span more than one LAN because they carry Network layer and addressing information that can be interpreted by a router.

Front 61

socket

Back 61

A logical address assigned to a specific process running on a computer. Some sockets are reserved for operating system functions.

Front 62

static ARP table entry

Back 62

A record in an ARP table that someone has manually entered using the ARP utility. Static ARP table entries remain the same until someone manually modifies them with the ARP utility.

Front 63

static IP address

Back 63

An IP address that is manually assigned to a device and remains constant until it is manually changed.

Front 64

subnet

Back 64

A part of a network in which all nodes shares a network addressing component and a fixed amount of bandwidth.

Front 65

subnet mask

Back 65

In IPv4 addressing, a 32-bit number that, when combined with a device’s IP address, indicates what kind of subnet the device belongs to.

Front 66

subnetting

Back 66

The process of subdividing a single class of network into multiple, smaller networks.

Front 67

subprotocols

Back 67

The specialized protocols that work together and belong to a protocol suite.

Front 68

switch

Back 68

The letters or words added to a command that allow you to customize a utility’s output. Switches are usually preceded by a hyphen or forward slash character.

Front 69

TCP

Back 69

(Transmission Control Protocol) A core protocol of the TCP/IP suite. TCP belongs to the Transport layer and provides reliable data delivery services.

Front 70

TCP/IP

Back 70

(Transmission Control Protocol/Internet Protocol) A suite of networking protocols that includes TCP, IP, UDP, and many others. TCP/IP provides the foundation for data exchange across the Internet.

Front 71

TCP/IP core protocols

Back 71

The major subprotocols of the TCP/IP suite, including IP, TCP, and UDP.

Front 72

Telnet

Back 72

A terminal emulation protocol used to log on to remote hosts using the TCP/IP protocol. Telnet resides in the Application layer of the OSI model.

Front 73

TFTP

Back 73

(Trivial File Transfer Protocol) A TCP/IP Application layer protocol that enables file transfers between computers. Unlike FTP, TFTP relies on UDP at the Transport layer and does not require a user to log on to the remote host.

Front 74

TLD

Back 74

(top-level domain) The highest-level category used to distinguish domain names—for example, .org, .com, and .net. A TLD is also known as the domain suffix.

Front 75

UDP

Back 75

(User Datagram Protocol) A core protocol in the TCP/IP suite that sits in the Transport layer of the OSI model. UDP is a connectionless transport service.

Front 76

unicast address

Back 76

A type of IPv6 address that represents a single interface on a device. An IPv6 unicast address begins with either FFC0 or FF80.

Front 77

Well Known Ports

Back 77

The TCP/IP port numbers 0 to 1023, so named because they were long ago assigned by Internet authorities to popular services (for example, FTP and Telnet), and are, therefore, well known and frequently used.

Front 78

Zeroconf

Back 78

(Zero Configuration) A collection of protocols designed by the IETF to simplify the setup of nodes on a TCP/IP network. Zeroconf assigns a node an IP address, resolves the node’s host name and IP address without requiring a DNS server, and discovers services, such as print services, available to the node, also without requiring a DNS server.

Front 79

TTL

Back 79

(Time to Live) A number that indicates the maximum time that a datagram or packet can remain on the network before it is discarded. Although this field was originally meant to represent units of time, on modern networks it represents the number of router hops a datagram has endured. The TTL for datagrams is variable and configurable, but is usually set at 32 or 64. Each time a datagram passes through a router, its TTL is reduced by 1. When a router receives a datagram with a TTL equal to 1, the router discards that datagram.