Each IP Network address is written as four parts separated by dots. Each of these parts comprises 8 binary bits. The 8 binary bit make an octet, so that each IP address has four octets. For example, the IP address 192.168.0.1 is made up of 4 octets having the following binary bits:-
11000000.10101000.00000000.00000001
The IP addresses are grouped into classes. The classes are defined by the most significant four bits of the first octet. The tables below show a short form of the IP addresses and their classes.
Classes
|
Class
|
First Octet
|
First 4 Bits
|
Remarks
|
|
A
|
1 - 127
|
0000
|
|
|
B
|
128 - 191
|
1000
|
|
|
C
|
192 - 223
|
1100
|
|
|
D
|
224 - 239
|
1110
|
Multicast
|
|
E
|
240 - 255
|
1111
|
Experimental
|
Loopback Testing
|
Class
|
First 2 Octets
|
Remarks
|
|
A
|
127.0 - 127.255
|
|
Private
|
Class
|
IP Address
|
CIDR Prefix
|
|
A
|
10.0.0.0 - 10.255.255.255
|
10.0.0.0 /8
|
|
B
|
172.16.0.0 - 172.31.255.255
|
172.16.0.0 /12
|
|
C
|
192.168.0.0 - 192.168.255.255
|
192.168.0.0 /16
|
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(c) Compiled by B V Wood.
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