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Appendix D: Glossary
IP Address
Psion Teklogix 9160 G2 Wireless Gateway User Manual D -59
The current version of IP is IPv4 . A new version, called IPv6 or IPng, is under development.
IPv6 is an attempt to solve the shortage of IP addresses.
IP Address
Systems are defined by their IP address , a four-byte (octet) number uniquely defining each
host on the Internet. It is usually shown in form
192.168.2.254
. This is called dotted-decimal
notation.
An IP address is partitioned into two portions: the network prefix and a host number on that
network. A
Subnet Mask is used to define the portions. There are two special host numbers:
• The Network Address consists of a host number that is all zeroes (for example,
192.168.2.0
).
• The Broadcast Address consists of a host number that is all ones (for example,
192.168.2.255
).
There are a finite number of IP addresses that can exist. Therefore, a local area network
typically uses one of the
IANA
-designated address ranges for use in private networks. These
address ranges are:
10.0.0.0
to
10.255.255.255
172.16.0.0
to
172.31.255.255
192.168.0.0
to
192.168.255.255
A Dynamic IP Address is an IP address that is automatically assigned to a host by a DHCP
server or similar mechanism. It is called dynamic because you may be assigned a different
IP address each time you establish a connection.
A Static IP Address is an IP address that is hard-wired for a specific host. A static address is
usually required for any host that is running a server, for example, a Web server.
IPSec
IP Security (IPSec) is a set of protocols to support the secure exchange of packets at the IP
layer. It uses shared public keys. There are two encryption modes: Transport and Tunnel.
• Transport mode encrypts only the data portion (payload) of each packet, but leaves the
headers untouched.
• The more secure Tunnel mode encrypts both the header and the payload.