User's Manual

Subnet Mask
242 Check Point Safe@Office User Guide
Subnet Mask
A 32-bit identifier indicating
how the network is split into
subnets. The subnet mask
indicates which part of the IP
address is the host ID and which
indicates the subnet.
T
TCP
TCP (Transmission Control
Protocol) is a set of rules
(protocol) used along with the
Internet Protocol (IP) to send
data in the form of message units
between computers over the
Internet. While IP takes care of
handling the actual delivery of
the data, TCP takes care of
keeping track of the individual
units of data (called packets) that
a message is divided into for
efficient routing through the
Internet.
For example, when an HTML
file is sent to you from a Web
server, the Transmission Control
Protocol (TCP) program layer in
that server divides the file into
one or more packets, numbers
the packets, and then forwards
them individually to the IP
program layer. Although each
packet has the same destination
IP address, it may get routed
differently through the network.
At the other end (the client
program in your computer), TCP
reassembles the individual
packets and waits until they have
arrived to forward them to you
as a single file.
TCP/IP
TCP/IP (Transmission Control
Protocol/Internet Protocol) is the
underlying communication
protocol of the Internet.
U
UDP
UDP (User Datagram Protocol)
is a communications protocol
that offers a limited amount of
service when messages are
exchanged between computers in
a network that uses the Internet
Protocol (IP). UDP is an
alternative to the Transmission
Control Protocol (TCP) and,
together with IP, is sometimes
referred to as UDP/IP. Like the
Transmission Control Protocol,
UDP uses the Internet Protocol
to actually get a data unit (called
a datagram) from one computer
to another. Unlike TCP,
however, UDP does not provide
the service of dividing a message
into packets (datagrams) and
reassembling it at the other end.