End Node

A node such as a PC that can only send and receive information for its own use. It cannot route and forward information to another node. 
 

Ethernet
 
The most popular LAN technology in use today. The IEEE standard 802.3 defines the rules for configuring an Ethernet network. It is a 10 Mbps, CSMA/CD baseband network that runs over thin coax, thick coax, twisted pair or fiber optic cable.

 
EtherTalk
 
Apple Computer's protocol for Ethernet transmissions. 

Exploit
 
An exploit is a piece of malware – in this case a rootkit - that takes advantage of a newly-announced or otherwise unpatched vulnerability. These vulnerabilities are most often found in operating systems, browsers, and other applications that routinely connect to the web, like media players and PDF readers.

Exploits can be hidden on any kind of web page – recent victims include Alicia Keys’ MySpace page and the Major League Baseball (MLB.com) site. They are usually delivered as a drive-by download which – as its name implies – happens invisibly, without your knowledge.

FDDI 
 
Fiberoptic Data Distribution Interface. A cable interface capable of transmitting data at 100 Mbps. Originally specified for fiber lines, FDDI can also operate over twisted-pair cable for short distances. 
 

Fiber-Optic Cable 
 
A transmission medium composed of a central glass optical fiber cable surrounded by cladding and an outer protective sheath. It transmits digital signals in the form of modulated light from a laser or LED (light-emitting diode). 
 

File Server
 
A computer that stores data for network users and provides network access to that data. 
 

Filtering
 
Process whereby an Ethernet switch or bridge reads the contents of a packet and then finds that the packet does not need to be forwarded, drops it. a filtering rate is the rate at which a device can receive packets and drop them without any loss of incoming packets or delay in processing. 
 

Firmware
 
Alterable programs in semipermanent storage, e.g., some type of read-only or flash reprogrammable memory. 
 

Forwarding
 
Process whereby an Ethernet switch or bridge reads the contents of a packet and then passes that packet on to the appropriate attached segment. A forwarding rate is the time that it takes the device to execute all of the steps. 
 

Flash ROM
 
See ROM. 
 

Framing
 
Dividing data for transmission into groups of bits, and adding a header and a check sequence to form a frame. 
 

FTP
 
File Transfer Protocol, a TCP/IP protocol for file transfer. 
 

Full-Duplex
 
Independent, simultaneous two-way transmission in both directions, as opposed to half-duplex transmission.

 
Gateway
 
A device for interconnecting two or more dissimilar networks. It can translate all protocol levels from the Physical layer up through the Applications layer of the OSI model, and can therefore interconnect entities that differ in all details.

Hardware Address
 
See Network Address.
 

Header 
 
The initial part of a data packet or frame containing identifying information such as the source of the data, its destination, and length.
 

Heartbeat
 
Ethernet defined SQE signal quality test function. 
 

Hertz (Hz)
 
A frequency unit equal to one cycle per second. 
 

Host
 
Generally a node on a network that can be used interactively, i.e., logged into, like a computer. 
 

Host Table
 
A list of TCP/IP hosts on the network along with their IP addresses.