Every computer connected to the Internet is assigned a unique number known as an Internet Protocol (IP) address. IP addresses consist of four numbers separated by periods (also called a “dotted-quad”) and look something like 127.0.0.1
Ex: Consider a colony as a network and number of houses in that colony as hosts. The house in a colony can be identified only with the help of Address and that address represents the IP Address.
IP Packet: This is sending IP data from one host to another host which is equivalent to writing a letter to a friend.
Ex: Consider a postal cover where, the message is considered as the data in IP packet, envelop cover is the IP header and address is the IP address.
The four numbers in an IP address are used in different ways to identify a particular network and a host on that network. Three regional internet registries – ARIN, RIPE, NCC and APNIC – assign Internet addresses from the following three classes.
Class A – supports 16 million hosts on each of 126 networks.
Class B – supports 65,000 hosts on each of 16,000 networks.
Class C – supports 254 hosts on each of 2 million networks.
The number of unassigned Internet addresses is running out, so a new classless scheme called CIDR is gradually replacing the system based on classes A, B, C and is tied to adoption of IPv6.
Class A – 18.104.22.168 to 22.214.171.124
Class B – 126.96.36.199 to 188.8.131.52
Class C – 184.108.40.206 to 220.127.116.11
Class D – 18.104.22.168 to 22.214.171.124 Reserved for multicast
Class E – 240.0.0.0 to 254.255.255.254 Reserved