Ethernet - IEEE standard network protocol that specifies how data is placed on and retrieved
from a common transmission medium. Has a transfer rate of 10 Mbps. Forms the underlying
transport vehicle used by several upper-level protocols, including TCP/IP and XNS.
DDNS (Dynamic Domain Name System) - Allows a network device with a dynamic Internet IP
address to have a fixed host and domain name, such as myhostname.mydomainname.com. It is
useful when you are hosting your own website, FTP server, or other server behind a router, so
people can find your site no matter how often the Internet IP address changes. Using DDNS
requires registering with a DDNS service provider on the Internet.
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.
DNS - The Domain Name System (DNS) is the way that Internet domain names are located and
translated into Internet Protocol (IP) addresses. A domain name is a meaningful and
easy-to-remember “handle” for an Internet address.
Domain - A sub network comprised of a group of clients and servers under the control of one
security database. Dividing LANs into domains improves performance and security.
Firmware - Code that is written onto read-only memory (ROM) or programmable read-only
memory (PROM). Once firmware has been written onto the ROM or PROM, it is retained even
when the device is turned off.
Full Duplex - The ability of a device or line to transmit data simultaneously in both directions.
Gateway – A device that interconnects networks with different, incompatible communications
protocols.
Half Duplex - Data transmission that can occur in two directions over a single line, but only one
direction at a time.
Hardware - Hardware is the physical aspect of computers, telecommunications, and other
information technology devices. The term arose as a way to distinguish the “box” and the
electronic circuitry and components of a computer from the program you put in it to make it do
things. The program came to be known as the software.
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