Private IP Address Classes
The IP addresses were not randomly classified into classes but a clear logic was applied to divide them into various classes. These classes also dictated the number of IP address any class could hold.
Let me first tell you the classes of IP address and how they are categorized. There are 3 MAIN classes of IP addresses. CLASS A, CLASS B, CLASS C.
You may be aware that the IP address is a block of 4 numbers separated by the DOT symbol, the division was based on a simple calculation. Here's how:
In class A, the first bit of the LAST block is always ZERO. The range for class B IP address could be from 00000001 - 01111111 (1 - 127). Any IP address in the range of 220.127.116.11 - 127.0.0.0 is a valid Class A IP address
In class B, the Second bit of the LAST block is always ZERO. The range for class B IP address could be from 10000000 - 10111111 (128 - 191). Any IP address in the range of 18.104.22.168 - 22.214.171.124 is a valid Class B IP address
In class C, the third bit of the LAST block is always ZERO. The range for class C IP address could be from 11000000 - 11011111 (192 - 223). Any IP address in the range of 192.0.0.0 - 126.96.36.199 is a valid Class C IP address
To Save the IP addresses for ever growing demand, a set of IP addresses were reserved for private use. These IP addresses cannot not be routed over the internet and meant for use internally.
The following are the private IP addresses in the 3 classes:
Class A: 10.0.0.0 Subnet: 255.0.0.0
Class B: 172.16.0.0 - 172.16.30.0 Subnet: 255.255.0.0
Class C: 192.168.1.0 Subnet 255.255.255.0