Linksys PPS1UW - Manual (Page 26)

Basically, a firewall, working closely with a router, examines each network
packet to determine whether to forward it toward its destination.
Firmware - Code that is written onto read-only memory (ROM) or program-
mable 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, telecommunica-
tions, and other information technology devices. The term arose as a way to dis-
tinguish 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.
HTTP (HyperText Transport Protocol) - The communications protocol used to
connect to servers on the World Wide Web. Its primary function is to establish a
connection with a Web server and transmit HTML pages to the client browser.
Hub - The device that serves as the central location for attaching wires from
workstations. Can be passive, where there is no amplification of the signals; or
active, where the hubs are used like repeaters to provide an extension of the
cable that connects to a workstation.
IEEE (The Institute of Electrical and Electronics Engineers) - The IEEE
describes itself as “the world’s largest technical professional society, promoting
the development and application of electrotechnology and allied sciences for
the benefit of humanity, the advancement of the profession, and the well-being
of our members.”
The IEEE fosters the development of standards that often become national and
international standards. The organization publishes a number of journals, has
many local chapters, and several large societies in special areas, such as the
IEEE Computer Society.
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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 dis-
tribute 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 espe-
cially useful in education and other environments where users change fre-
quently. 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.
Domain - A subnetwork comprised of a group of clients and servers under the
control of one security database. Dividing LANs into domains improves per-
formance and security.
Driver - A workstation or server software module that provides an interface
between a network interface card and the upper-layer protocol software running
in the computer; it is designed for a specific card, and is installed during the
initial installation of a network-compatible client or server operating system.
DSSS (Direct-Sequence Spread-Spectrum) - DSSS generates a redundant bit
pattern for each bit to be transmitted. This bit pattern is called a chip (or chip-
ping code). The longer the chip, the greater the probability that the original data
can be recovered. Even if one or more bits in the chip are damaged during
transmission, statistical techniques embedded in the radio can recover the orig-
inal data without the need for retransmission. To an unintended receiver, DSSS
appears as low power wideband noise and is rejected (ignored) by most nar-
rowband receivers.
Firewall - A firewall is a set of related programs, located at a network gateway
server, that protects the resources of a network from users from other networks.
(The term also implies the security policy that is used with the programs.) An
enterprise with an intranet that allows its workers access to the wider Internet
installs a firewall to prevent outsiders from accessing its own private data
resources and for controlling what outside resources to which its own users
have access.
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