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CSMA/CD
A method of managing traffic and reducing noise on an Ethernet
network. A network device transmits data after detecting that a
channel is available. However, if two devices transmit data simul-
taneously, the sending devices detect a collision and retransmit
after a random time delay.
DHCP
A utility that enables a server to dynamically assign IP addresses
from a predefined list and limit their time of use so that they
can be reassigned. Without DHCP, an IT Manager would have to
manually enter in all the IP addresses of all the computers on
the network. When DHCP is used, whenever a computer logs
onto the network, it automatically gets an IP address assigned
to it.
Dial-up
A communication connection via the standard telephone net-
work, or Plain Old Telephone Service (POTS).
DNS
A program that translates URLs to IP addresses by access-
ing a database maintained on a collection of Internet servers.
The program works behind the scenes to facilitate surfing the
Web with alpha versus numeric addresses. A DNS server con-
verts a name like mywebsite.com to a series of numbers like
107.22.55.26. Every website has its own specific IP address on
the Internet.
DSL
Various technology protocols for high-speed data, voice and
video transmission over ordinary twisted-pair copper POTS
(Plain Old Telephone Service) telephone wires.
Encryption key
An alphanumeric (letters and/or numbers) series that enables
data to be encrypted and then decrypted so it can be safely
shared among members of a network. WEP uses an encryption
key that automatically encrypts outgoing wireless data. On the
receiving side, the same encryption key enables the computer to
automatically decrypt the information so it can be read.
Firewall
Keeps unauthorized users out of a private network. Everything
entering or leaving a system’s internal network passes through
the firewall and must meet the system’s security standards in
order to be transmitted. Often used to keep unauthorized peo-
ple from using systems connected to the Internet.
Hub
A multiport device used to connect PCs to a network via
Ethernet cabling or via WiFi. Wired hubs can have numerous
ports and can transmit data at speeds ranging from 10 Mbit/s
to multigigabyte speeds per second. A hub transmits packets it
receives to all the connected ports. A small wired hub may only
connect 4 computers; a large hub can connect 48 or more.