Cross Linking Websites

Because of the numbering scheme outlined in part 1 of this article, and because of the way blocks of address's were assigned in the early days of the internet, there is a shortage of unique IP address's.

This means that when you buy your $10/month hosting package (which is really a great deal when you consider what you get for it these days) you do not usually get your own unique IP address for your web site, you share it with others.

IP address are classified into 3 class's (groups) depending on the decimal equivalent of the 1st octet in the address as below:
0-255.xxx.xxx.xxx = all address's

Class A
Intended for a small number of networks that had a large number of computers (hosts) attached. Class A IP Address have a value in the range 1...126 as the first octet. The values 0 and 127 are not available because they have special uses. Class A addresses use the first octet to identify the network which means that 126 addresses are usable, each of which can support 16,777,216 computers (hosts).

Class B
Intended for some networks that had an intermediate number of computers (hosts) attached. Class B IP Addresses have a value in the range 128...191 as the first octet. Class B addresses use the first two octets to identify the network which means that 16,320 addresses are usable, each of which can support 65,536 computers (hosts).

Class C
Intended for a large number of networks that would have a small (relatively) number of computers (hosts) attached. Class C IP Addresses have a value in the range 192...223 as the first octet. Class C addresses use the first three octets to identify the network which means that 2,080,800 addresses are possible, each of which can support 254 computers (hosts).

See part 2 Cross Linking Websites