Tài liệu Glossary of Networking Terms docx

Glossary of
Networking Terms
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578

Glossary of Networking Terms

10Base-2

An implementation of Ethernet that specifies a 10Mbps sig-
naling rate, baseband signaling, and coaxial cable with a maximum segment
length of 185 meters (approximately 607 feet).

85% policy

A Web site design policy that encourages the use of technolo-
gies that will reach many people but not let the stragglers drag functionality
down for other viewers. The Web site is designed so that the majority of
Internet users can view its content.

abend

Short for

ab

normal

end

. Novell’s term for a server crash.

ABEND.LOG

The log file in the

SYS:\SYSTEM

directory on a NetWare 4.11
or later server that records all abends that have occurred on a NetWare server,
including detailed information regarding the abend.

access control

Any system that keeps people from accessing resources
they don’t need. If they can’t access it, they can’t steal it.

Access Control List (ACL)

The list of rights an object has to resources in
the network. Also a type of firewall. In this case, the lists reside on a router
and determine which machines can use the router and in what direction.

access log

A Web server log file that indicates who has accessed which
resource. The access log records the IP address of the accessing station, the
time and date of the access, which file was accessed, and the protocol used

to access it.

ACK

See

acknowledgment.

acknowledgment (ACK)

A message confirming that the data packet was
received. This occurs at the Transport layer of the OSI model.

ACL

See

Access Control List.

active detection

A type of intruder detection that constantly scans the
network for possible break-ins.

active monitor

Used in Token Ring networks, a process that prevents
data frames from roaming the ring unchecked. If the frame passes the active
monitor too many times, it is removed from the ring. Also ensures that a
token is always circulating the ring.

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579

Active Server Pages (ASP)

The server-side scripting solution for
Microsoft Web servers—mainly, Internet Information Server (IIS).

adaptive content policy

A Web site design policy in which Web sites
don’t necessarily have to choose between accessibility and glamour. Instead,
sites can deliver advanced features to clients that can use them and standard
features to clients who can’t use advanced features. In this way, the whole
audience is well served. Writing the Web site to work in this way, however,
adds complexity and often cost.

Adobe Acrobat

A file format that is used on the Internet to distribute files
that contain graphics and text in a specified layout. Acrobat allows users on
diverse platforms to view (and in its latest version, annotate) documents that
incorporate text, graphics, hyperlinks, and complex layouts. It’s better than
HTML because the publisher has absolute control over how the publication
looks on users’ machines. Acrobat files carry a

.PDF

filename extension.

American Standard Code for Information Interchange (ASCII)

The
standard code used to convert decimal numbers used during computer com-
munications into characters, numbers, and symbols for display on screen.

antivirus

A category of software that uses various methods to eliminate
viruses in a computer. It typically also protects against future infection.

See
also

virus.

Application layer

Layer seven of the OSI model; the Application layer
deals with how applications access the network and describes application
functionality, such as file transfer, messaging, and so on.

application log

Windows NT log file, viewable in the Event Viewer, that
is used to keep track of events for network services and applications.

application server

Any server that hosts a network application.

ARCNet

The Attached Resource Computer Network, which was devel-
oped by Datapoint Corporation in the late 1970s as one of the first baseband
networks. It can use either a physical star topology or a bus topology.
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580

Glossary of Networking Terms

ARP table

A table used by the ARP protocol. Contains a list of known
TCP/IP addresses and their associated MAC addresses. The table is cached in
memory so that ARP lookups do not have to be performed for frequently
accessed TCP/IP and MAC addresses.

See also

Address Resolution Protocol;
media access control; Transmission Control Protocol/Internet Protocol.

ASCII

See

American Standard Code for Information Interchange (ASCII).

ASP

See

Active Server Pages (ASP).

Asynchronous Transfer Mode (ATM)

A connection-oriented network
architecture based on broadband ISDN technology that uses constant-size
53-byte cells instead of packets. Because cells don’t change size, they are
switched much faster and more efficiently than packets across a network.

AT command set

A set of modem initialization commands developed by
the Hayes company for their modems, so named because each command
begins with

AT

.

See also

modem initialization commands.

ATM

See

Asynchronous Transfer Mode.

Attachment Unit Interface (AUI) port

On some NICs, a port through
which the NIC can be connected to different media types by using an
external transceiver.

Audio Visual Interleaved (AVI) files

A video file format that has support
for full-motion video and animation with sound. Developed for the Windows
environment by Microsoft, AVI files usually have

.AVI

filename extensions.

auditing

A system of record keeping in which special software takes notes
of what is happening on a network and why and allows administrators to
look at those notes (called log files) later.

authentication

The process of verifying that a person (or a piece of soft-
ware, in situations where programs share information without human inter-
vention) is who he claims to be.

AVI files

See

Audio Visual Interleaved (AVI) files.

B channel

See

Bearer channel.
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Glossary of Networking Terms

581

backbone ISP

An ISP with very high-speed connections (several hundred
megabits per second) to the other backbone ISPs. These connections form
the “backbone” of the Internet

.

backup domain controller (BDC)

Computer on a Windows NT network
that has a read-only copy of the SAM database for fault-tolerance and per-
formance-enhancement purposes.

See also

Security Accounts Manager.

bandwidth

In network communications, the amount of data that can be
sent across a wire in a given time (usually in one second). Each communica-
tion that passes along the wire decreases the amount of available bandwidth.

banner ads

A rectangular graphic, generally about 500 pixels wide by 60
pixels tall, that’s placed on a Web page, usually to sell some items or services.
When a surfer clicks a banner ad, he’s taken to the advertiser’s Web site (and
usually, the fact that he got there through a banner ad is noted).

baseband

A transmission technique in which the signal uses the entire
bandwidth of a transmission medium.

baseline

A category of network documentation that indicates how the net-
work normally runs. It includes such information as network statistics,
server utilization trends, and processor performance statistics.

Bearer channel

The channels in an ISDN line that carry data (also called
the B channel). Each Bearer channel typically has a bandwidth of 64Kbps.

bindery

Flat database used in NetWare 3.

x

and earlier servers to store net-
work resource information (such as user, group, and security information).
Each server in the network has its own bindery database.

BinHex

The MacOS file compression standard. The BinHex format allows
you to combine several files into one compressed unit and extract them indi-
vidually. They usually have an

.HQX

filename extension.

biometric authentication

A type of authentication that uses fingerprints,
retinal scan, voiceprints, face recognition, and other biologically unique fea-
tures of humans instead of passwords for network authentication.

Bit Fiddler

A virus that changes small random bits in files.
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582

Glossary of Networking Terms

BNC connector

Tubular connectors most commonly used with
coaxial cable.

boot sector virus

A virus that overrides the boot sector, thereby making it
appear as if there is no pointer to your operating system. When this happens,
you will see a “Missing operating system” or “Hard disk not found” error
message on power-up.

bounded medium

A network medium where the signal travels over a
cable of some kind.

bridge

A network device, operating at the Data Link layer, that logically
separates a single network into segments but lets the two segments appear to
be one network to higher-layer protocols.

broadband

A network transmission method in which a single transmis-
sion medium is divided so that multiple signals can travel across the same
medium simultaneously.

brouter

A connectivity device that will act as a router for routable proto-
cols and act as a bridge for nonroutable protocols.

brownout

See

power brownout.

browser

A computer program that uses the Hypertext Transfer Protocol

and is used on a workstation to access hosts on the Web.

brute force attack

A type of network attack where the attacker simply
uses a computer to generate random combinations of characters in the hope
of stumbling onto the correct combination for a password. Brute force
attacks rely on the capacity of attacking computers to tirelessly generate dif-
ferent combinations of characters and feed them to defended network
resources.

burst mode

An addition to NCP that allows multiple date frames to be
sent without waiting for an acknowledgment for the previous frame of data.

See also

NetWare Core Protocol.

business-to-business commerce

Businesses providing goods and ser-
vices to other businesses.
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Glossary of Networking Terms

583

bytecodes

The result of running Java source code through a Java com-
piler. This result is used within an imaginary chip called the Java Virtual
Machine (JVM).

See also

Java Virtual Machine (JVM).

C

A general-purpose programming language that can be used to write pro-
grams for various platforms. The code must be specifically written for a par-
ticular platform, however.

C++

An object-oriented version of C.

See also

C.

CA

See

certification authority.

cable

A physical transmission medium that has a central conductor of wire
or fiber surrounded by a plastic jacket.

cable map

A general network documentation indicating each cable’s
source and destination as well as where each network cable runs.

cable tester

See

time-domain reflectometer.

cache-in-a-box

A “black box” that you plug into your network to increase
Internet surfing by caching portions of frequently accessed Web sites.

CAD program

Any program that is used during the computer-aided design
(CAD) process; typically used by engineers.

captive audience policy

A type of Web content policy that by which Web

site creators create the content in the format they want, their audience must
use only browsers that work with these content types. Captive audience pol-
icies usually rely on the content creators also having control of the browsers
people have on their desktops.

carrier sense multiple access with collision avoidance (CSMA/CA)

A
media access method that sends a request to send (RTS)



packet and waits to
receive a clear to send (CTS)



packet before sending. Once the CTS is
received, the sender sends the packet of information.

carrier sense multiple access with collision detection (CSMA/CD)

A
media access method that senses whether there is a signal on the wire, indi-
cating that someone is transmitting currently. If no one else is transmitting,
it attempts a transmission and listens to hear whether someone else tries
to transmit at the same time. If this happens, both senders back off and
don’t transmit again until some random period of time has passed.
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Glossary of Networking Terms

centralized WAN

A WAN with a computer that connects computers and
dumb terminals to a central site.

See also

wide area network.

certificate

Proof that someone (or something) is what he or she (or it)
claims to be.

certification authority

An organization that’s responsible for verifying
the identity of people and issuing certificates to those whose identities can be
verified. Also known as a certificate authority.

CGI

See

Common Gateway Interface.

ciphertext

Text after it has been encrypted.

CIR

See

Committed Information Rate.

cleartext

Normal text before it is encrypted.

Client Services for NetWare (CSNW)

Software that allows Windows NT
computers to access NetWare resources.

client-server network A server-centric network in which all resources are
stored on a file server; processing power is distributed among workstations
and the file server.
client-side markup language Any system of adding tags (markup) to a
text document in order to supply information about how the text should be
rendered in a Web browser or what it means. Client-side markup languages
are interpreted by Web browsers.
clipper chip A hardware implementation of the skipjack encryption
algorithm.
coaxial cable Often referred to as coax. A type of cable used in network

wiring. Typical coaxial cable types include RG-58 and RG-62. 10Base-2
Ethernet networks use coaxial cable. Coaxial cable is usually shielded.
cold site backup system A backup system that does not run continu-
ously. Therefore, before you can restore data, the computer must be repaired
and the software must be reloaded on the server.
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Glossary of Networking Terms 585
collision The error condition that occurs when two stations on a CSMA/
CD network transmit data (at the Data link layer) at the same time. See also
carrier sense multiple access with collision detection.
Committed Information Rate (CIR) A commitment from your service
provider stating the minimum bandwidth you will get on a Frame Relay
network.
Common Gateway Interface (CGI) A specification that defines a way of
packaging text data (such as the contents of a form) for transmission over a
network. The CGI specification takes the contents of a form and the names
of the form elements (as specified in HTML) and assembles them all into a
long string of characters. That string can then be passed to a program on the
server side for processing and a response.
compiler A special software program that translates the human-readable
source code of a programming language into machine code that processors
and operating systems can understand. Compilers are usually specific to a
programming language.
Component Object Model (COM) The Microsoft “twin” to JavaBeans.
It’s a means of writing independent code modules and having them commu-
nicate with one another. The idea is that you could have a single, specialized
COM module that various other pieces of software (other COM modules
and non-COM programs) refer to for different reasons. Unlike JavaBeans,
however, COM currently will work only on Windows (and some Unix)

machines.
concentrator See hub.
connectionless protocol A transport protocol, such as UDP, that does
not create a virtual connection between sending and receiving stations. See
also User Datagram Protocol.
connection-oriented protocol A transport protocol that uses acknowl-
edgments and responses to establish a virtual connection between sending
and receiving stations. TCP is a connection-oriented protocol. See also
Transmission Control Protocol.
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586 Glossary of Networking Terms
CONSOLE.LOG A NetWare server log file that keeps a history of all errors
and information that has been displayed on the server’s console since the
CONLOG.NLM file was loaded.
contention A media access method that allows any computer to transmit
whenever it has data. Every station has an equal opportunity to transmit.
cookie A special text message given to a Web browser by a Web server.
The browser stores this message on the local hard disk. The next time
someone using that Web browser on that computer visits the same Web
server, the Web browser sends this message back to the Web server (which
created it). Cookies are used to provide customized Web sites for users.
copyleft A legal term whereby an organization (usually a not-for-profit
group like the Free Software Foundation) establishes copyright to an item of
intellectual property—source code for software, usually—then distributes it
free of charge. People who use the software must agree to its licensing agree-
ment, which specifies that they may not make a profit on its distribution. The
GNU utilities are covered by copyleft.
copyright The right of an author, artist, publisher, or other legal entity to
collect money from the use of words, music, performance works, items of

visual art, or other creative products.
country codes The two-letter abbreviations for countries; used in the
DNS hierarchy. See also Domain Name Services.
CRC See cyclical redundancy check.
crossover cable The troubleshooting tool used in Ethernet UTP installa-
tions to test communications between two stations, bypassing the hub. See
also unshielded-twisted pair.
cross-sell The process of selling the buyer of a given product accessories
and other related products.
CSMA/CA See carrier sense multiple access with collision avoidance.
CSMA/CD See carrier sense multiple access with collision detection.
CSNW See Client Services for NetWare.
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Glossary of Networking Terms 587
cyclical redundancy check (CRC) An error-checking method in data
communications that runs a predefined formula against data before trans-
missions. The sending station then appends the resultant value (called a
checksum) to the data and sends it. The receiving station uses the same for-
mula on the data. If the receiving station doesn’t get the same checksum
result for the calculation, it considers the transmission invalid, rejects the
frame, and asks for a retransmission.
Data Encryption Standard (DES) A government standard for private key
systems that has lookup table functions and fast encryption. A 64-bit private
key is used. See also private key; public key.
Data Link layer The second layer of the OSI model; the Data Link layer
describes the logical topology of a network—the way that packets move
throughout a network. It also describes the method of media access. See also
Open Systems Interconnection.
data mining The process by which applications attempt to analyze the

data in databases and draw conclusions from it.
data packet A unit of data sent over a network. A packet includes a
header, addressing information, and the data itself. A packet is treated as a
single unit as it is sent from device to device.
database Any collection of data, usually organized in some fashion.
Database Management System (DBMS) A program that adds data to
databases, extracts data from them, organizes the data for various applica-
tions, and generally attempts to guarantee that the database is fast, easily
accessible, and secure from outsiders.
database server Any program that’s responsible for maintaining one or
more databases and responding to queries sent to them. This definition also
refers to a type of server that runs database server software.
datagram A unit of data smaller than a packet.
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588 Glossary of Networking Terms
Dataphone Digital Service (DDS) line This type of Internet bandwidth
link technology from AT&T is a dedicated, point-to-point connection with
throughput anywhere from 2400bps to 56Kbps. The 56Kbps digital connec-
tion is the most common, and this type of line has since obtained the moniker
56K Line. When not purchased from AT&T, this line is known as a Digital
Data Service line.
DBMS See Database Management System (DBMS).
DCOM See Distributed Component Object Model (DCOM).
default gateway The router that all packets are sent to when the work-
station doesn’t know where the destination station is or when it can’t find
the destination station on the local segment.
Defense Advanced Research Projects Agency (DARPA) The govern-
ment agency responsible for the creation of ARPAnet, on which the founda-
tion for the Internet was laid.

Delta channel A channel used for link management on an ISDN line. See
also Integrated Services Digital Network.
demilitarized zone (DMZ) The special area (defined by a firewall) where
all public access servers are located, protected from outside attack yet avail-
able to users on both sides of the firewall.
denial of service (DOS) attack Type of attack that prevents any users,
even legitimate ones, from using the system and its resources.
DES See Data Encryption Standard.
DHCP See Dynamic Host Configuration Protocol.
differential backup Backs up data that has changed since the last full
backup.
digital Any signal that has discrete values over time. A digital signal has no
transition between values. It is one value in one instant (that is, a specific
number, such as 1) and a different value the next (that is, a second number,
such as 0).
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Glossary of Networking Terms 589
digital certificate Digital proof that someone is who he claims to be on the
Internet.
digital signature Pieces of electronic information that serve to guarantee
that an item—a document, a credit card number, whatever—was not tam-
pered with as it traveled over the Internet from sender to recipient. By exam-
ining a digital signature that arrives with a piece of data, you can be sure that
the data has arrived in exactly the same state it was in when it left the
sender’s computer.
Digital Subscriber Line (DSL) A digital WAN technology that brings
high-speed digital networking to homes and businesses over POTS. There
are many types, such as HDSL (High Data Rate Digital Subscriber Line) and
VDSL (Very High Data Rate Digital Subscriber Line). See also Public

Switched Telephone Network.
directory A network database that contains a listing of all network
resources, such as users, printers, groups, and so on.
directory service A network service that provides access to a central data-
base that contains detailed information about the resources available on a
network.
disk drive subsystem The entire set of hard disks, controllers, and soft-
ware that makes up the storage component of a workstation or a server.
disk drivers NLMs that provide NetWare with access to the disk channel.
See also NetWare Loadable Module.
disk striping Technology that enables writing data to multiple disks
simultaneously in equal portions called stripes. These stripes maximize use
by having all of the read/write heads working constantly. Different data is
stored on each disk and is not automatically duplicated (this means that disk
striping in and of itself does not provide fault tolerance).
distance vector A route-discovery method in which each router, using
broadcasts, tells every other router what networks and routes it knows about
and the distance to them.
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590 Glossary of Networking Terms
Distributed Component Object Model (DCOM) A subset of COM that
includes COM modules running on different machines and referring to one
another across a network. See also Component Object Model (COM).
distributed computing A technology where portions of a computing job
are spread over several machines.
DLL See Dynamic Link Library.
DMZ See demilitarized zone.
DDNS See Dynamic DNS.
DNS resolver Client software used to make requests of the DNS server in

order to resolve DNS host names into IP addresses. See also Domain Name
Services; Internet Protocol.
DNS server Any server that performs DNS host name to IP address reso-
lution. See also Domain Name Services; Internet Protocol.
DNS zone An area in the DNS hierarchy that is managed as a single unit.
See also Domain Name Services.
document type definition (DTD) A common XML specification that
allows one party to publish data in conformance with a DTD so that another
party, having access to the same DTD, can interpret the information
published.
DOD Networking Model A four-layer conceptual model describing how
communications should take place between computer systems. The four
layers are Process/Application, Host-to-Host, Internet, and Network Access.
domain A group of networked Windows computers that share a single
SAM database. See also Security Accounts Manager.
Domain Name Services (DNS) Used in TCP/IP networks, the network
service that translates host names to IP addresses. See also Transmission
Control Protocol/Internet Protocol.
drive mapping The process of assigning a drive letter at the client to a
directory or folder on the server.
DSL See Digital Subscriber Line.
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Glossary of Networking Terms 591
D-type connector A type of network connector that connects computer
peripherals. It contains rows of pins or sockets shaped in a sideways D.
dumb terminal A keyboard and monitor that send keystrokes to a central
processing computer (typically a mainframe or minicomputer) and return
screen displays to the monitor. The unit has no processing power of its own,
hence, the moniker dumb.

duplexed hard drives Two hard drives to which identical information is
written simultaneously. A dedicated controller card controls each drive.
Used for fault tolerance.
Dynamic DNS (DDNS) A Windows 2000 feature that dynamically regis-
ters a DNS host name for network workstations as they are brought online.
See also Domain Name Services.
dynamic entry An entry made in the ARP table whenever an ARP request
is made by the Windows TCP/IP stack and the MAC address is not found in
the ARP table. The ARP request is broadcast on the local segment. When the
MAC address of the requested IP address is found, that information is added
to the ARP table. See also Address Resolution Protocol; Internet Protocol;
media access control; Transmission Control Protocol/Internet Protocol.
Dynamic Host Configuration Protocol (DHCP) A protocol used on a
TCP/IP-based network to send client configuration data—including TCP/IP
address, default gateway, subnet mask, and DNS configuration—to clients.
See also Domain Name Services; default gateway; subnet mask; Transmis-
sion Control Protocol/Internet Protocol.
Dynamic Link Library (DLL) Small pieces of executable Windows code
that Windows programmers use so they don’t have to write commonly used
routines into each program.
dynamic packet filtering The process of using a firewall to monitor the
packets involved in an exchange between the Internet and a private network
and rejecting those that don’t match patterns for “safe” packets.
dynamic routing The use of route discovery protocols to talk to other
routers and find out what networks they are attached to. Routers that use
dynamic routing send out special packets to request updates of the other
routers on the network as well as to send their own updates.
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592 Glossary of Networking Terms

dynamic state list A list that is held on a firewall and changes as commu-
nication sessions are added and deleted. Only computers that are in a current
communication session are allowed to send information back and forth.
E1 An E1 is the same style channel as a T1 connection, but it is a European
standard and is made up of 32 64Kbps channels for a total throughput of
2.048Mbps. See also T1.
E3 E3 is a bandwidth technology for Europe that uses 480 64Kbps chan-
nels for a total bandwidth of 34.368Mbps.
e-commerce The exchange of money and goods using the Internet as the
exchange medium.
e-commerce server An Internet Web server that provides e-commerce
services through Web server scripts or programs.
EEPROM See electronically erasable programmable read-only memory.
electromagnetic interference (EMI) The interference that can occur
during transmissions over copper cable because of electromagnetic energy
outside the cable. The result is degradation of the signal.
electronic mail (e-mail) An application that allows people to send mes-
sages via their computers on the same network or over the Internet.
electronically erasable programmable read-only memory (EEPROM)
A special integrated circuit on expansion cards that allows data to be stored
on the chip. If necessary, the data can be erased by a special configuration
program. Typically used to store hardware configuration data for expan-
sion cards.
electrostatic discharge (ESD) A problem that exists when two items with
dissimilar static electrical charges are brought together. The static electrical
charges jump to the item with fewer electrical charges, causing ESD, which
can damage computer components.
emergency scan A scan used after a virus has taken control of a com-
puter. An emergency antivirus boot disk is used.
EMI See electromagnetic interference.

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Glossary of Networking Terms 593
Encapsulated PostScript (EPS) files A graphics file format where the
graphic is recorded in the PostScript printer language, which means it’s pos-
sible to generate a PostScript file on one computer and print it on any Post-
Script printer, even if the computer to which the printer is connected
contains no software that understands PostScript. Web browsers don’t sup-
port EPS, though, so its application to Internet publishing is limited.
encoding The process of translating data into signals that can be trans-
mitted on a transmission medium.
encryption Any method of converting a readable message into a coded
message for secure transmission over an unsecure medium (for example, the
Internet).
encryption algorithm Also called a hashing algorithm. A sequence of
mathematical procedures that alters the text and encrypts it, thus rendering
it unreadable.
encryption key A string of alphanumeric characters used to encrypt and
decrypt a message. A message cannot be encrypted or decrypted without
the key.
ENS See Event Notification Services.
enterprise computing The process of sharing information among the
applications with which an organization, such as a company or a unit of gov-
ernment, does its business.
EPS files See Encapsulated PostScript (EPS) files.
error log A type of Web server log file that logs any errors reported by the
Web server.
ESD See electrostatic discharge.
Ethernet A shared-media network architecture. It operates at the Physical
and Data Link layers of the OSI model. It uses baseband signaling over either

a bus or a star topology with CSMA/CD as the media access method. The
cabling used in Ethernet networks can be coax, twisted-pair, or fiber-optic.
See also carrier sense multiple access with collision detection; Open Systems
Interconnection (OSI).
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594 Glossary of Networking Terms
Event Notification Services (ENS) A component of Novell Directory
Print Services (NDPS) broker that notifies users and administrators of
network-printing events. See also Novell Directory Print Services.
expansion slot A slot on the computer’s bus. Expansion cards are plugged
into these slots to expand the functionality of the computer (for example, if
you plug in a NIC card, you can add the computer to a network). See also
network interface card.
eXtensible Markup Language (XML) A type of markup language that
describes what the text in a browser window means. Rather than lock Web
publishers into a universal set of tags that must be made to apply in all situ-
ations (as HTML does), XML allows users to define their own tags as
needed.
failover server A hot site backup system in which the failover server is
connected to the primary server. A heartbeat is sent from the primary server
to the backup server. If the heartbeat stops, the failover system starts and
takes over. Thus, the system doesn’t go down, although the primary server
is not running.
fair use Copyright law recognizes that a vibrant creative community relies,
in part, on artists’ ability to use the creative products of others as starting
points for their own creative work. Such applications of copyrighted mate-
rial are known as fair use applications in the law.
fault-resistant network A network that will be up and running at least 99
percent of the time or that is down less than 8 hours a year.

fault-tolerant network A network that can recover from minor errors.
fax server A computer with a special fax board that sends and receives
faxes without the need for paper. It delivers and receives faxes for the entire
network.
FDDI See Fiber Distributed Data Interface.
FDM See frequency division multiplexing.
Fiber Distributed Data Interface (FDDI) A network topology that uses
fiber-optic cable as a transmission medium and dual, counter-rotating rings
to provide data delivery and fault tolerance.
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fiber-optic A type of network cable that uses a central glass or plastic core
surrounded by a plastic coating.
fibre channel A type of server-to-storage system connection that uses
fiber-optic connectors.
File and Print Services for NetWare (FPNW) A method of providing
files and printers hosted by Windows NT to Novell clients. When installed
and configured on a Windows NT server, this service makes a Windows NT
server look like a NetWare server to Novell clients.
file server A server that specializes in holding and distributing files.
File Transfer Protocol (FTP) A TCP/IP protocol and software that permit
the transfer of files between computer systems. Because FTP has been imple-
mented on numerous types of computer systems, files can be transferred
between disparate computer systems (for example, a personal computer and
a minicomputer). See also Transmission Control Protocol/Internet Protocol.
firewall A combination of hardware and software that protects a network
from attack by hackers that could gain access through public networks,
including the Internet.
forms Collections of user interface elements that include text fields, check

boxes, radio buttons, selection lists, and several kinds of buttons to allow a
user to enter information into an HTML page.
FPNW See File and Print Services for NetWare.
FQDN See fully qualified domain name.
Frame Relay A WAN technology that uses packet switching to transmit
packets over a WAN. See also packet switching.
frequency division multiplexing (FDM) The division of a single trans-
mission medium into multiple channels so that multiple signals can be car-
ried on the medium simultaneously, each using a different frequency.
FTP See File Transfer Protocol.
FTP proxy A server that uploads and downloads files from another server
on behalf of a workstation.
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full backup A backup that copies all the data to the archive medium.
full-featured development language A programming language that can
be used to write stand-alone programs. You can use a full-featured develop-
ment language to write an elaborate word processor, a Web browser, or a
database front end.
fully qualified domain name (FQDN) An address that uses both the host
name (workstation name) and the domain name.
gateway The hardware and software needed to connect two disparate net-
work environments so that communications can occur.
Gateway Services for NetWare Software that is installed as a service on
a Windows NT server and translates requests for Windows NT resources
into NetWare requests. It also translates SMB protocol requests into NCP
requests. It allows multiple Windows NT clients to connect through a Win-
dows NT server to NetWare servers using only Windows NT client software
and protocols. See also NetWare Core Protocol; Server Message Block.

GIF See Graphics Interchange Format.
global group A type of group in Windows NT that is used in multiple-
domain environments. Members from the local domain can be placed into
global groups, which can be used anywhere in the network, and rights can be
assigned to any resource in the network.
Gopher A text-based utility that was used in the early years of the Internet
to search for data and news. This utility would present selections in a hier-
archical format. Developed from work done at the University of Minnesota.
Their mascot was the gopher, so they named this technology Gopher.
Grandfather-Father-Son (GFS) backup method A standard rotation
scheme for backup tapes. Daily backups are the Son, the last full back
up of the week is the Father, and the last full backup of the month is the
Grandfather.
Graphics Interchange Format (GIF) A graphics file type that specifies
images that consist of from 2 to 256 colors.
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ground loop A condition that occurs when a signal cycles through a
common ground connection between two devices, causing EMI interference.
See also electromagnetic interference.
grouping A method for organizing users (into administrator groups,
printer groups, and so on, for example) that eases network administration.
Gzip A Unix file compression utility similar to WinZip. Gzip files usually
have a .GZ filename extension. Gzip is often applied to tar files to further
compress them.
HAL See Hardware Abstraction Layer.
HAM See Host Adapter Module.
Hardware Abstraction Layer (HAL) The layer in the Windows NT archi-
tecture that makes Windows NT platform independent. A new HAL is

required to run Windows NT on a platform other than the commonly
accepted choices (Intel, MIPS, Alpha).
hardware address A Data Link layer address assigned to every NIC at the
MAC sublayer. The address is in the format xx:xx:xx:xx:xx:xx; each xx is
a two-digit hexadecimal number. See also network interface card; media
access control.
Hardware Compatibility List (HCL) The list of Microsoft-recommended
hardware for running Windows operating system software. Hardware must
be on this list to be truly compatible with Windows operating systems.
hardware loopback Connects the transmission pins directly to the
receiving pins, allowing diagnostic software to test whether a NIC can suc-
cessfully transmit and receive. See also network interface card.
HCL See Hardware Compatibility List.
header The section of a packet where the source and destination address
reside.
hop One pass through a router. See also router.
host Any network device with a TCP/IP network address. See also Trans-
mission Control Protocol/Internet Protocol.
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Host Adapter Module (HAM) A feature of the NetWare Peripheral Archi-
tecture that provides communication with the host adapter.
HOSTS file A file within many operating systems (including Windows 95/98
and NT and Unix) that provides manual host name to IP address resolution. The
file must be edited on each client machine with a list of all host names and IP
addresses on the network.
hot backup system A complete duplicate of a set of computing services
stored in a server room. If the main system fails, it can take over operation
without any downtime.

HTML See Hypertext Markup Language.
HTML forms See forms.
HTML tags See tags.
HTTP See Hypertext Transfer Protocol.
hub A Physical layer device that serves as a central connection point for
several network devices. Also known as a concentrator, a hub repeats the sig-
nals it receives on one port to all other ports.
Hypertext Markup Language (HTML) A set of codes used to format text
and graphics that will be displayed in a browser. The codes define how data
will be displayed.
Hypertext Transfer Protocol (HTTP) The protocol used for communica-
tion between a Web server and a Web browser.
IBM data connector Used to connect IBM Token Ring stations using
Type 1 STP cable. This connector is both male and female, so every IBM data
connector can connect to any other IBM data connector. See also shielded
twisted-pair.
ICMP See Internet Control Message Protocol.
IEEE See Institute of Electrical and Electronics Engineers.
IEEE 802.x standards The IEEE standards for LAN and MAN networking.
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Glossary of Networking Terms 599
IEEE 802.1 LAN/MAN Management Standard that specifies LAN/MAN
network management and internetworking.
IEEE 802.2 Logical Link Control Standard that specifies the operation of
the Logical Link Control (LLC) sublayer of the Data Link layer of the OSI
model. The LLC sublayer provides an interface between the MAC sublayer
and the Network layer. See also media access control; Open Systems Inter-
connection.
IEEE 802.3 CSMA/CD Networking Standard that specifies a network

that uses a logical bus topology, baseband signaling, and a CSMA/CD net-
work access method. See also carrier sense multiple access with collision
detection.
IEEE 802.4 Token Bus Standard that specifies a physical and logical bus
topology that uses coaxial or fiber-optic cable and the token passing media
access method.
IEEE 802.5 Token Ring Specifies a logical ring, physical star, and token
passing media access method based on IBM’s Token Ring.
IEEE 802.6 Distributed Queue Dual Bus (DQDB) Metropolitan Area
Network
Provides a definition and criteria for a DQDB metropolitan area
network (MAN).
IEEE 802.7 Broadband Local Area Networks Standard for broadband
cabling technology.
IEEE 802.8 Fiber-Optic LANs and MANs A standard containing guide-
lines for the use of fiber-optics on networks, which includes FDDI and
Ethernet over fiber-optic cable. See also Fiber Distributed Data Interface;
Ethernet.
IEEE 802.9 Integrated Services (IS) LAN Interface A standard con-
taining guidelines for the integration of voice and data over the same cable.
IEEE 802.10 LAN/MAN Security A series of guidelines dealing with var-
ious aspects of network security.
IEEE 802.11 Wireless LAN Defines standards for implementing wireless
technologies such as infrared and spread-spectrum radio.
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600 Glossary of Networking Terms
IEEE 802.12 Demand Priority Access Method Defines standards that
combine the concepts of Ethernet and ATM. See also Asynchronous
Transfer Mode; Ethernet.

IETF See Internet Engineering Task Force.
incremental backup Backs up data that has changed since the last full or
incremental backup.
Institute of Electrical and Electronics Engineers (IEEE) An international
organization that sets standards for various electrical and electronics issues.
Integrated Services Digital Network (ISDN) A telecommunications
standard that is used to digitally send voice, data, and video signals over the
same lines.
Intel 386 (I386) architecture Platform that includes the 386, 486, Pen-
tium, Pentium Pro, Pentium II, and Pentium III processors.
intellectual property A legal term that denotes any intangible product of
a human being, a group of human beings, or another legal entity (such as a
corporation). That product then further belongs to the individual or group
that created it. It is a legal way of allowing an idea to be copyrighted.
International Organization for Standardization (ISO) The standards
organization that developed the OSI model. This model provides a guideline
for how communications occur between computers.
Internet A global network made up of a large number of individual net-
works interconnected through the use of public telephone lines and TCP/IP
protocols. See also Transmission Control Protocol/Internet Protocol.
Internet Architecture Board (IAB) The committee that oversees manage-
ment of the Internet. It is made up of two subcommittees: the Internet Engi-
neering Task Force (IETF) and the Internet Research Task Force (IRTF). See
also Internet Engineering Task Force; Internet Research Task Force.
Internet bandwidth link The communications pathway between the var-
ious LANs that make up the Internet.
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Internet commerce Any sort of business that is facilitated by the

Internet. Usually, the term applies primarily to commerce that involves a
Web site of some kind.
Internet Control Message Protocol (ICMP) A message and management
protocol for TCP/IP, primarily used for error checking. The Ping utility uses
ICMP. See also Ping; Transmission Control Protocol/Internet Protocol.
Internet Engineering Task Force (IETF) An international organization
that works under the Internet Architecture Board to establish standards and
protocols relating to the Internet. See also Internet Architecture Board.
Internet layer Layer of the DOD model that corresponds to the Network
layer of the OSI model. See also Open Systems Interconnection.
Internet Protocol (IP) The protocol in the TCP/IP protocol suite respon-
sible for network addressing and routing. See also Transmission Control
Protocol/Internet Protocol.
Internet Research Task Force (IRTF) An international organization that
works under the Internet Architecture Board to research new Internet tech-
nologies. See also Internet Architecture Board.
Internet Service Provider (ISP) A company that provides, usually for a
fixed monthly fee, direct access to the Internet for home and business com-
puter users.
Internet-in-a-box Specialized devices that provide Internet access to an
entire network over a single Internet connection quickly and easily.
Internetwork Packet eXchange (IPX) A connectionless, routable net-
work protocol based on the Xerox XNS architecture. It is the default pro-
tocol for versions of NetWare before NetWare 5. It operates at the Network
layer of the OSI model and is responsible for addressing and routing packets
to workstations or servers on other networks. See also Open Systems Inter-
connection; Xerox Network System.
intranet server HTTP servers that are located on a company’s LAN and
serve information only to employees of that company or any other user who
has been given authority to view it.

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