What is an IP address?

By | July 10, 2009

What is an IP address?

IP address is a 32-bit numeric address written as four numbers separated by periods. Each number can be zero to 255. The four numbers in an IP address are called octets and that is how each octet have eight positions when viewed in binary form. Every machine on the Internet­ has a unique identifying number, called an IP Address. For example,

* 216.27.61.137

­To make it easier for us humans to remember, IP addresses are normally expressed in decimal format as a “dotted decimal number” like the one above. But computers communicate in binary form. Look at the same IP address in binary:

* 11011000.00011011.00111101.10001001

In an isolated network, you can assign IP addresses at random as long as each one is unique. However, connecting a private network to the Internet requires using registered IP addresses (called Internet addresses) to avoid duplicates. IP addresses are registered by Regional Internet Registries. ARIN, RIPE NCC, LACNIC and APNIC, AFRI-NIC — assign Internet addresses from Class A, B, & C.

Out of the almost 4.3 billion possible combinations, certain values are restricted from use as typical IP addresses. For example, the IP address 0.0.0.0 is reserved for the Default Network and the address 255.255.255.255 is used for Broadcasts. IP address 127.0.0.1 is used as the loopback address, used by the host computer to send a message back to itself

The octets are split into two sections: Net and Host. The Net section always contains the first octet. Host (sometimes referred to as Node) identifies the actual computer on the network. The Host section always contains the last octet.