network plus
A form of directory service used in networks with Windows servers. Creates an organization of related computers that share one or more Windows domains.
Active Directory ...
A block cipher created in the late 1990s that uses a 128-bit block size and a 128-, 192-, or 256-bit key size. Practically uncrackable.
Advanced Encryption Standard (AES) ...
A router hierarchy in which every router underneath a higher router always uses a subnet of that router's existing routes.
Aggregation...
A set of rules for solving a problem in a given number of steps.
Algorithm...
The basic ISDN configuration, which consists of two B channels (which can carry voice or data at a rate of 64 Kbps) and one D channel (which carries setup and configuration information, as well as data, at 16 Kbps).
Basic Rate Interface (BRI) ...
A network topology that uses a single bus cable that connects all of the computers in line. Bus topology networks must be terminated to prevent signal reflection.
Bus Topology...
Device that can tap into a 66- or 110-punchdown block to see if a particular line is working.
Butt Set ...
Short for "cabinet files." These files are compressed and most commonly used during Microsoft operating system installation to store many smaller files, such as device drivers.
CAB Files...
Category 3 wire, a TIA/EIA standard for UTP wiring that can operate at up to 16 Mbps.
CAT 3...
Category 4 wire, a TIA/EIA standard for UTP wiring that can operate at up to 20 Mbps. This wire is not widely used, except in older Token Ring networks.
CAT 4...
Category 5 wire, a TIA/EIA standard for UTP wiring that can operate at up to 100 Mbps.
CAT 5...
Category 5e wire, a TIA/EIA standard for UTP wiring with improved support for 100 Mbps using two pairs and support for 1000 Mbps using four pairs.
CAT 5e...
Category 6 wire, a TIA/EIA standard for UTP wiring with improved support for 1000 Mbps.
CAT 6...
A bridge device that interconnects the cable company's DOCSIS service to the user's Ethernet network. In most locations, the cable modem is the demarc.
Cable Modem...
DNS servers that do not have any forward lookup zones. They resolve names of systems on the Internet for the network, but are not responsible for telling other DNS servers the names of any clients.
Cache-Only DNS Servers (Caching-Only DNS Servers) ...
The list kept by a DNS server of IP addresses it has already resolved, so it won't have to re-resolve an FQDN it has already checked.
Cached Lookup ...
Engine A server dedicated to storing cache information on your network. These servers can reduce overall network traffic dramatically.
Caching...
Less common type of DNS record that acts as a computer's alias.
Canonical Name (CNAME) ...
A process by which a printer uses a local LPT port that connects to a networked printer. This is usually only done to support older programs that are not smart enough to know how to print directly to a UNC-named printer; it's quite rare today.
Capturing a Printer...
A public encryption key signed with the digital signature from a trusted third party called a certificate authority (CA). This key serves to validate the identity of its holder when that person or company sends data to other parties.
Certificate ...
A series of complex and hard-to-reverse mathematics run on a string of ones and zeroes in order to make a new set of seemingly meaningless ones and zeroes.
Cipher...
The output when cleartext is run through a cipher algorithm using a key.
Ciphertext ...
In Kerberos, a system that hands out Ticket-Granting Tickets to clients after comparing the client hash to its own. See also Ticket-Granting Ticket (TGT).
(AS) Authentication Server...
An encryption algorithm in which data is encrypted in "chunks" of a certain length at a time. Popular in wired networks.
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Bit Error Rate Test (BERT) An end-to-end test that verifies a T-carrier connection.
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GLOSSARY
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An Ethernet LAN designed to run on UTP cabling. Runs at 100 Mbps, uses baseband signaling, and uses two pairs of wires on CAT 5 or better cabling.
...100BaseT
An Ethernet LAN designed to run on UTP cabling. Runs at 100 Mbps and uses four-pair CAT 3 or better cabling. Made obsolete by 100BaseT.
...100BaseT4
The technically accurate but little-used name for 100BaseT.
...100BaseTX
fiber-optic implementation of Ethernet that runs at 10 megabits per second (Mbps) using baseband signaling. Maximum segment length is 2 km.
...10BaseFL
An Ethernet LAN designed to run on UTP cabling. Runs at 10 Mbps and uses baseband signaling. Maximum length for the cabling between the NIC and the hub (or the switch, the repeater, and so forth) is 100 m.
...10BaseT
A 10 GbE standard using 1550-nm single-mode fiber. Maximum cable length up to 40 km.
...10GBaseER/10GBaseEW
A 10 GbE standard using 1310-nm single-mode fiber. Maximum cable length up to 10 km.
...10GBaseLR/10GBaseLW
A 10 GbE standard using 850-nm multimode fiber. Maximum cable length up to 300 m.
...10GBaseSR/10GBaseSW
standard designed to run on CAT 6a UTP cabling. Maximum cable length of 100 m.
...10GBaseT A 10 GbE
Block The most common connection used on the back of an RJ-45 jack and patch panels.
...110-Punchdown
A Gigabit Ethernet standard using unique copper cabling, with a 25-m maximum cable distance.
1000BaseCX...
An umbrella Gigabit Ethernet standard. Also known as 802.3z. Comprises all Gigabit standards with the exception of 1000BaseT, which is under the 802.3ab standard.
1000BaseX...
Currently (2012) the wireless standard with the widest use, 802.11g operates on the 2.4-GHz band with a maximum throughput of 54 Mbps.
802.11g...
A wireless standard that added security features.
802.11i ...
An updated 802.11 standard that increases transfer speeds and adds support for multiple in/multiple out (MIMO) by using multiple antennas. 802.11n can operate on either the 2.4- or 5-GHz frequency band and has a maximum throughput of 400 Mbps.
802.11n...
A wireless standard (also known as WiMax) with a range of up to 30 miles.
802.16...
A list of the IP addresses and names of all the systems on a DNS server domain.
A Records...
A document that defines what a person may and may not do on an organization's computers and networks.
Acceptable Use Policy...
A clearly defined list of permissions that specifies what actions an authenticated user may perform on a shared resource.
Access Control List (ACL) ...
An LED on a NIC, hub, or switch that blinks rapidly to show data transfers over the network.
Activity Light...
A wireless networking mode where each node is in direct contact with every other node in a decentralized free-for-all. Ad hoc mode is similar to the mesh topology.
Ad Hoc Mode...
A protocol in the TCP/IP suite used with the command-line utility of the same name to determine the MAC address that corresponds to a particular IP address.
Address Resolution Protocol (ARP) ...
each aspect of a network, from documentation to performance to hardware.
Asset Management Managing...
(ADSL) A fully digital, dedicated connection to the telephone system that provides download speeds of up to 9 Mbps and upload speeds of up to 1 Mbps.
Asymmetric Digital Subscriber Line...
A networking feature in operating systems that enables DHCP clients to self-configure an IP address and subnet mask automatically when a DHCP server isn't available.
Automatic Private IP Addressing (APIPA) ...
One or more networks that are governed by a single protocol within that AS, which provides routing for the Internet backbone.
Autonomous System (AS) ...
In wireless networking, a single access point servicing a given area.
Basic Service Set (BSS) ...
Naming scheme in wireless networks.
Basic Service Set Identifier (BSSID) ...
One analog cycle on a telephone line.
Baud ...
A type of ISDN channel that carries data and voice information using standard DS0 channels at 64 Kbps.
Bearer Channel (B Channel) ...
Two or more NICs in a system working together to act as a single NIC to increase performance.
Bonding ...
A component of TCP/IP that allows computers to discover and receive an IP address from a DHCP server prior to booting the OS. Other items that may be discovered during the BOOTP process are the IP address of the default gateway for the subnet and the IP addresses of any name servers.
Bootstrap Protocol (BOOTP) ...
An exterior gateway routing protocol that enables groups of routers to share routing information so that efficient, loop-free routes can be established.
Border Gateway Protocol (BGP-4) ...
A group of computers under the control of one operator, used for malicious purposes.
Botnet ...
A negative situation in which bridging devices (usually switches) are installed in a loop configuration, causing frames to loop continuously. Switches using Spanning Tree Protocol (STP) prevent bridge loops by automatically turning off looping ports.
Bridge Loop...
An early type of DSL connection that made the DSL line function the same as if you snapped an Ethernet cable into your NIC.
Bridged Connection ...
Analog signaling that sends multiple signals over the cable at the same time. The best example of broadband signaling is cable television. The zero, one, and idle states exist on multiple channels on the same cable. See also Baseband.
Broadband ...
The address a NIC attaches to a frame when it wants every other NIC on the network to read it. In TCP/IP, the general broadcast address is 255.255.255.255. In Ethernet, the broadcast MAC address is FF-FF-FF-FF-FF-FF.
Broadcast Address...
The result of one or more devices sending a nonstop flurry of broadcast frames on the network.
Broadcast Storm...
A frame or packet addressed to all machines, almost always limited to a broadcast domain.
Broadcast...
Domain A network of computers that will hear each other's broadcasts. The older term collision domain is the same, but rarely used today.
Broadcast...
Rating A grade assigned to cable to help network installers get the right cable for the right network technology. CAT ratings are officially rated in megahertz (MHz), indicating the highest-frequency bandwidth the cable can handle.
Category (CAT) ...
A device that tests a cable to ensure that it can handle its rated amount of capacity.
Certifier ...
A remote access authentication protocol. It has the serving system challenge the remote client, which must provide an encrypted password.
Challenge Handshake Authentication Protocol (CHAP) ...
A set of documents that defines procedures for changes to the network.
Change Management Documentation ...
A portion of the wireless spectrum on which a particular wireless network operates. Setting wireless networks to different channels enables separation of the networks.
Channel ...
Wireless technology that enables WAPs to use two channels for transmission.
Channel Bonding...
A Gigabit Ethernet standard using multimode fiber cabling, with a 5-km maximum cable distance.
1000BaseSX...
The number of bauds per second. In the early days of telephone data transmission, the baud rate was often analogous to bits per second. Due to advanced modulation of baud cycles as well as data compression, this is no longer true.
...Baud Rate
The umbrella IEEE standard for all versions of Gigabit Ethernet other than 1000BaseT.
...802.3z
A port-authentication network access control mechanism for networks.
...802.IX
Currently (2012) the fastest Ethernet designation available, with a number of fiber-optic and copper standards.
...10 Gigabit Ethernet (10 GbE)
An Ethernet LAN designed to run on fiber-optic cabling. Runs at 100 Mbps and uses baseband signaling. Maximum cable length is 400 m for half-duplex and 2 km for full-duplex.
...100BaseFX
The IEEE committee responsible for all Ethernet standards.
...802 Committee
A wireless standard that operates in the frequency range of 5 GHz and offers throughput of up to 54 Mbps.
...802.11a
The first popular wireless standard, which operates in the frequency range of 2.4 GHz and offers throughput of up to 11 Mbps.
...802.11b
The IEEE standard for 1000BaseT.
...802.3ab
A Gigabit Ethernet standard using single-mode fiber cabling, with a 220- to 500-m maximum cable distance.
1000BaseLX...
A Gigabit Ethernet standard using CAT 5e/6 UTP cabling, with a 100-m maximum cable distance.
1000BaseT ...
A method of addressing groups of computers as though they were a single computer. Anycasting starts by giving a number of computers (or clusters of computers) the same IP address. Advanced routers then send incoming packets to the closest of the computers.
Anycast...
Tracks application events, such as when an application opens or closes. Different types of application logs record different events.
Application Log...
An attribute of a file that shows whether the file has been backed up since the last change. Each time a file is opened, changed, or saved, the archive bit is turned on. Some types of backups turn off this archive bit to indicate that a good backup of the file exists on tape.
Archive Bit...
Address assigned to routers in an OSPF network to prevent flooding beyond the routers in that particular network. See also Open Shortest Path First (OSPF).
Area ID...
An encryption method in which the key used to encrypt a message and the key used to decrypt it are different, or asymmetrical.
Asymmetric-Key Algorithm...
(ATM) A network technology that runs at speeds between 25 and 622 Mbps using fiber-optic cabling or CAT 5 or better UTP.
Asynchronous Transfer Mode...
xThe degradation of signal over distance for a networking cable.
Asynchronous Transfer Mode...
Servers DNS servers that hold the IP addresses and names of systems for a particular domain or domains in special storage areas called forward lookup zones.
Authoritative DNS...
A connector used for 10Base2 coaxial cable. All BNC connectors have to be locked into place by turning the locking ring 90 degrees.
BNC Connector...
Digital signaling that has only one signal (a single signal) on the cable at a time. The signals must be in one of three states: one, zero, or idle.
Baseband...
Static image of a system's (or network's) performance when all elements are known to be working properly.
Baseline...
A simple form of NAT that translates a computer's private or internal IP address to a global IP address on a one-to-one basis.
Basic NAT...
6in4
One of the most popular of all the IPv6 tunneling standards, and one of only two IPv6 tunneling protocols that can go through a NAT.
6to4
The dominant IPv6 tunneling protocol because it is the only IPv6 tunnel that doesn't require a tunnel broker. It is generally used to directly connect two routers because it normally requires a public IPv4 address.
A command used to discover hosts on a network, similar to ping, but that relies on ARP rather than ICMP. The arping command won't cross any routers, so it will only work within a broadcast domain. See also Address Resolution Protocol (ARP) and ping.
arping...