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CAT 5
- ANSI/EIA (American National Standards Institute/Electronic Industries
Association) Standard 568 is one of several standards that specify “categories” (the
singular is commonly referred to as “CAT”) of twisted pair cabling systems (wires,
junctions, and connectors) in terms of the data rates that they can sustain. CAT 5 cable
has a maximum throughput of 100 Mbps and is usually utilized for 100BaseTX networks.
CAT 5e
- The additional cabling performance parameters of return loss and farend
crosstalk (FEXT) specified for 1000BASE-T and not specified for 10BASE-T and
100BASE-TX are related to differences in the signaling implementation. 10BASE-T and
100BASE-TX signaling is unidirectional—signals are transmitted in one direction on a
single wire pair. In contrast, Gigabit Ethernet is bi-directional—signals are transmitted
simultaneously in both directions on the same wire pair; that is, both the transmit and
receive pair occupy the same wire pair.
CPU (Central Processing Unit)
- The computing part of the computer. Also called the
“processor,” it is made up of the control unit and ALU.
Daisy Chain
- Connected in series, one after the other. Transmitted signals go to the
first device, then to the second, and so on.
Database
- A database is a collection of data that is organized so that its contents can
easily be accessed, managed, and updated.
Data Packet
- One frame in a packet-switched message. Most data communications is
based on dividing the transmitted message into packets. For example, an Ethernet
packet can be from 64 to 1518 bytes in length.
Default Gateway
- The routing device used to forward all traffic that is not addressed to
a station within the local subnet.
Demodulation
- Opposite of modulation; the process of retrieving data from a
modulated carrier wave.
DHCP (Dynamic Host Configuration Protocol)
- A protocol that lets network
administrators centrally manage and automate the assignment of Internet Protocol (IP)
addresses in an organization's network. Using the Internet’s set of protocol (TCP/IP),
each machine that can connect to the Internet needs a unique IP address. When an
organization sets up its computer users with a connection to the Internet, an IP address
must be assigned to each machine. Without DHCP, the IP address must be entered
manually at each computer and, if computers move to another location in another part of
the network, a new IP address must be entered. DHCP lets a network administrator
supervise and distribute IP addresses from a central point and automatically sends a
new IP address when a computer is plugged into a different place in the network. DHCP
uses the concept of a “lease” or amount of time that a given IP address will be valid for a
computer. The lease time can vary depending on how long a user is likely to require the
Internet connection at a particular location. It’s especially useful in education and other
environments where users change frequently. Using very short leases, DHCP can
dynamically reconfigure networks in which there are more computers than there are
available IP addresses. DHCP supports static addresses for computers containing Web
servers that need a permanent IP address.
DMZ - (DeMilitarized Zone)
allows one IP address (or computer) to be exposed to the
Internet. Some applications require multiple TCP/IP ports to be open. It is recommended
that you set your computer with a static IP address if you want to use DMZ Hosting.
DNS
- Domain Name System (DNS). The distributed name/address mechanism used in
the Internet..