For two or more computers to be able to communicate to a network it is necessary for them to identify each other uniquely. Now this is where IP address comes in. When a computer is connected to a network is automatically assigned an IP address.
This IP address allows computer to send their data packets to specific computers on the network. During communication an IP address is a string of 32 bits. Bits are split into 4 equal parts each containing 8 bits. These four binary numbers are then converted into decimal equivalent to give an IP address.
The way in which IP addresses are allocated Is very similar to our phone number Is located, in a sense that the phone number can be split into both the area code and ID code. Similarly IP address is Split up into a network Code and a host ID.
In the above mentioned IP address the first three decimals are used to identify the network. This however is not always the case. This is because the part which defines the network Part in an IP address depends on its class. There are five different types of IP address.
- Class A
- Class B
- Class C
- Class D
- Class E
Each of these classes have a specific functions. A to C are used for allocating IP address D is used for multi casting and E is reserved for experimental use. The actual difference between the classes is the way in which they are split between network and host.
In Class A IP address only the first part of the address is used as a network ID. The leading bit in Class A IP address Is always a zip. This means the remaining 7 bits in the first part can be used to create network IDs.
There are possible 2 to the seven networks IDs that can be created. The remaining 24 bits of the IP address can be used to create host IDs, using class a IP addresses you could have a possible 128 network each containing a possible of 2 to the 24 host.
Class B IP address uses the first two part of the address. To create the network code for the class B address the leading bits are 1 and 0.
This means the remaining for 14 bits can now be used to create the network ID causing the amount of possible networks to rise up to two to the 14. This time the remaining 16 bits are used to create the host IDs meaning a possible 2 to 16 hosts per network.
As the trend would suggest the class C IP address uses the first three parts of the address to create network ID. This time the leading bit is 110 leaving 21 Bits to create the network IDs, the amount of possible networks has increased to the 2 to the 21.
This leaves 8 bit to create the host ID. This means that on a class C IP address there are possible to 2 to the 21 that works is containing a possible 256 users.