What is IP address and what it represents?

Computers communicate over the Internet using the IP protocol (Internet Protocol), which uses numerical addresses, called IP addresses, made up of four whole numbers (4 bytes) between 0 and 255 and written in the format xxx.xxx.xxx.xxx. For example, 194.153.205.26 is an IP address given in technical format. These addresses are used by networked computers to communicate, so each computer on a network has a unique IP address on that network. Through the IP we can access the computer or any application running on the computer.

Four different parts of IP Address

An IP address is a 32 bit address, generally written in the format of 4 whole numbers separated by dots. There are two distinct parts to an IP address:

• the numbers to the left indicate the network and are called the netID,
• the numbers to the right indicate the computers on this network and are called the host-ID.

Shown in the example below: 

                                

Here's an example:

       130.5.5.25

Each of the decimal numbers represents a string of eight
binary digits. Thus, the above IP address really is this

string of 0s and 1s: 

       10000010.00000101.00000101.00011001

Some portion of the IP address represents the network number or address and some portion represents the local machine address (also known as the host number or address). IP addresses can be one of several classes, each determining how many bits represent the network number and how many represent the host number. The most common class used by large organizations (Class B) allows 16 bits for the network number and 16 for the host number. Using the above example, here's how the IP address is divided: 

          <--Network address--><--Host address-->                      130.5     .          5.25

 

if you wanted to add subnetting to this address, then some portion (in this example, eight bits) of the host address could be used for a subnet address. Thus: 

  <--Network address--><--Subnet address--><--Host address-->

              130.5      .       5           .      25

  

Take a network written 58.0.0.0. The computers on this network could have IP addresses going from 58.0.0.1 to 58.255.255.254. So, it is a case of allocating the numbers in such a way that there is a structure in the hierarchy of the computers and servers.

 

Static versus Dynamic IP Addresses

The discussion above assumes that IP addresses are assigned on a static basis. In fact, many IP addresses are assigned dynamically from a pool. Many corporate networks and online services economize on the number of IP addresses they use by sharing a pool of IP addresses among a large number of users. If you're an America Online user, for example, your IP address will vary from one logon session to the next because AOL is assigning it to you from a pool that is much smaller than AOL's base of subscribers.