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of the data (routing), TCP takes care of keeping track of the individual units of
data (called packets) that a message is divided into for efficient delivery over
the network. TCP is known as a "connection oriented" protocol due to requir-
ing the receiver of a packet to return an acknowledgment of receipt to the
sender of the packet resulting in transmission control.
TCP/IP (Transmission Control Protocol/Internet Protocol) - The basic com-
munication language or set of protocols for communications over a network
(developed specifically for the Internet). TCP/IP defines a suite or group of
protocols and not only TCP and IP.
Topology - A network's topology is a logical characterization of how the
devices on the network are connected and the distances between them. The
most common network devices include hubs, switches, routers, and gateways.
Most large networks contain several levels of interconnection, the most impor-
tant of which include edge connections, backbone connections, and wide-area
connections.
USB (Universal Serial Bus) - A "plug-and-play" interface between a comput-
er and peripherals, such as digital cameras, scanners, game controllers, speak-
ers, keyboards, portable data storage, or printers. With USB, you can add a new
peripheral to your computer without having to add an adapter card or powering
down the computer. USB also supports hot-swapping, the addition or removal
of devices while the computer is running.
USB 1.1-compliant devices support data rates of 1.5Mbps (low-speed) and up
to 12Mbps (full-speed). USB 2.0-compliant devices are backward compatible
with earlier USB devices, and they support data rates of 1.5Mbps (low-speed),
12Mbps (full-speed), and up to 480Mbps (high-speed).
WEP (Wired Equivalent Privacy) - A data privacy mechanism based on a 64-
bit or 128-bit shared key algorithm, as described in the IEEE 802.11 standard.
WLAN (Wireless Local Area Network) - A group of computers and associat-
ed devices that communicate with each other wirelessly.
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Server - Any computer whose function in a network is to provide user access
to files, printing, communications, and other services.
Software - Instructions for the computer. A series of instructions that performs
a particular task is called a "program." The two major categories of software are
"system software" and "application software." System software is made up of
control programs such as the operating system and database management sys-
tem (DBMS). Application software is any program that processes data for the
user.
A common misconception is that software is data. It is not. Software tells the
hardware how to process the data.
Spread Spectrum - Spread Spectrum technology is a wideband radio frequen-
cy technique developed by the military for use in reliable, secure, mission-crit-
ical communications systems. It is designed to trade off bandwidth efficiency
for reliability, integrity, and security. In other words, more bandwidth is con-
sumed than in the case of narrowband transmission, but the trade off produces
a signal that is, in effect, louder and thus easier to detect, provided that the
receiver knows the parameters of the spread-spectrum signal being broadcast.
If a receiver is not tuned to the right frequency, a spread-spectrum signal looks
like background noise. There are two main alternatives, Direct Sequence
Spread Spectrum (DSSS) and Frequency Hopping Spread Spectrum (FHSS).
SSID (Service Set IDentifier) - A unique name shared among all points in a
wireless network. The SSID must be identical for each point in the wireless net-
work and is case-sensitive.
Storage - The semi-permanent or permanent holding place for digital data.
Subnet Mask - The method used for splitting IP networks into a series of sub-
groups, or subnets. The mask is a binary pattern that is matched up with the IP
address to turn part of the host ID address field into a field for subnets.
Switch - 1. A data switch connects computing devices to host computers,
allowing a large number of devices to share a limited number of ports. 2. A
device for making, breaking, or changing the connections in an electrical cir-
cuit.
TCP (Transmission Control Protocol) - A method (protocol) used along with
the IP (Internet Protocol) to send data in the form of message units (datagram)
between network devices. While IP takes care of handling the actual delivery
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