IP addressing ?

IP Addressing

               If a device wants to communicate using TCP/IP, it needs an IP address. IP addressing was designed to allow hosts on one network to communicate with a host of different network. When the device has an IP Address and required hardware and software, it can send and receive IP packets. Any device that can send or receive IP packets is called an IP host.

It is a 32- bit numerical value which is divided into 4 octets, where each octet is of 8 bits.

There are 2 parts in an IP address i.e. Network ID and Host ID.

·        Network ID is the identification of  a network.

·        Host ID is the identification of host.

Class     Range      N/w bits       Host bit       Subnetmask   

 A         1 – 126         8                   24                  255.0.0.0

 B      128 – 191        16                  16                255.255.0.0

 C       192 – 223        24                 8                   255.255.255.0

 D       224 – 239              It is reserved for multicast.

 E        240 – 255        It is reserved for research/scientific use

                            (also used by NASA)

 127.0.0.0 – 127.255.255.255 is the loopback address. The purpose of  loopback range is testing of TCP/IP protocol implementation on a host. 127.0.0.1 is the address most commonly used for testing purposes.

Private Addresses- these addresses can be used on a private network but they are not routable through internet. By using private addresses, ISPs, corporations and home users only need a small groups to connect their networks to internet.

Subnet Mask- A subnet mask is a 32-bit value that allows the recipient of  IP packets to distinguish the network ID from host ID portion of IP Address. Subnet mask is also 32-bit address, which tells us how many bits are used for network and how many bits are used for host address.

In Subnet mask Network bits are always 1 and Host bits are always 0.