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ES3610/11 User Guide Appendix A: Guide to IP Addressing
I447GB issue 6 Page 51
What is an IP Address?
A full explanation of IP addressing is beyond the scope of this user guide. However the following
details will provide you with enough information to get started.
An IP Address is a 32-bit binary number that is used to identify each device on an Ethernet network.
This number is usually represented by four decimal numbers (each in the range 0 to 255) separated
by dots,
e.g. 198.123.34.240. This is called ‘dotted decimal notation’.
An IP Address is divided into two parts:
•
the ‘network identifier’, and
•
the ‘host identifier’.
On a given network each address must have the same network identifier value but have a unique host
identifier. There are, therefore, different ‘classes’ of address which define:
•
the range of valid addresses, and
•
which parts of the address are used for the network and host identifiers.
The most common IP Address classes are:
Class Name Valid Address Range Identifier Arrangement*
Class A 0.0.0.1 to 127.255.255.254 NNN.HHH.HHH.HHH
Class B 128.0.0.1 to 191.255.255.254 NNN.NNN.HHH.HHH
Class C 192.0.0.1 to 223.255.255.254 NNN.NNN.NNN.HHH
*Where:NNN = Network identifier
HHH = Host identifier
Private & Public Address Ranges
Within each of the above classes are a range of addresses designated as ‘private’ addresses. These
are addresses which should only ever be used on private local networks and intranets and cannot be
accessed directly from the internet.
10.0.0.0 – 10.255.255.255
172.16.0.0 – 172.31.255.255
169.254.0.0 –169.254.255.255
192.168.0.0 – 192.168.255.255
All other addresses outside these ranges are considered ‘public’ addresses.
Multicast Address Range
A further range of addresses are available for multicast usage:
224.0.0.0 – 239.255.255.255
These addresses (also known as Class D addresses) are used to allow several devices to be part of
the same multicast group. Each device in the group has the same multicast address and can
effectively send data to all other devices in the same group simultaneously.