IP protocol (Internet Protocol) is used in computer to communicate over the Internet. Here the numerical addresses are used i.e. called IP addresses. This is created of four whole numbers (4 bytes) between 0 and 255 and written in the format xxx.xxx.xxx.xxx. In technical format, we take an example, 203.163.105.36 as an IP address. Every computer on a network has a unique IP address on that network because network computers are used this for communicating. In IP addresses the number of bytes represents the network. Remembering this IP addresses are divided into classes which are class a IP address, class b IP address and class c IP address : 1>Class A - Major international company uses this type of large network. IP addresses with a first Octet 1 to 126 of IP addresses are belong to the class. Three octets are used for identifying the each host.126 Class A type networks are attached each with 16,777,214 (2²⁴ -2) possible hosts. As a result total of 2,147,483,648 (2³¹) unique IP addresses are used. The bit value which is in high order, there the very first octet is 0 (it is the very first binary number)

2>Class B - A uncast address lies in the range 128.0.0.1 to 191.255.255.254 in Internet Protocol version 4 (IPv4). Where the beginning set is of 2 bits in a 10 sequence that indicates a class B IP address. With the 16,384 (2 14) (this can be happened in theoretical),the next 14 bits can be able to identify the specific network. But the rest 16,382 network addresses remain available for assignment because addresses 0 and 16,383 are reserved for it.

3>Class C – The last part of IP address is class C type. Here any IP which lies in the last part are automatically indicates the class C part. This type of class is intended for a large number of networks. But here the condition is that it would have a few (relatively) number of computers (hosts) connected. The range of this type of class is 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 (networks) are possible, each of which can support 254 computers (hosts).This three types of classes can be also divided by their sizes. Among them class b IP address are in medium of size which means it is smaller than class A type but larger than class C type. If we use a class b of 172.16.0.0 with a mask of 255.255.192.0(subnet) with 30 workstations then we have to use 172.16.0.0->255.255.255.192.