Uniquely identifying a computer

All computers on the Internet must have a way to uniquely identify each other -- just like all telephones need a unique identifier, the phone number. Computers on the Internet have two such methods:

• IP Number: All computers on the Internet are identified by this unique 32-bit address. IP numbers are written with four parts separated with dots. It is very difficult for a human to make sense of IP numbers without a large directory.

• Domain Name System (DNS): To make computer identification easier for non-computers, there is a unique name which identifies an Internet site. Domain Names always have 2 or more parts, separated by dots. The part on the left is the most specific, and the part on the right is the most general.