IP Addressing and Subnetting

IP Addressing:

IP Addressing uses to identify each machine uniquely through its IP (Internet Protocol) address. An IP address is a 32-bit unique address (IPv4) given a host to the network interface. Even if the machine isn’t connected to the internet but connects to a LAN then it also the IP address of all the machines should be unique within the LAN. It consists of two parts:

i. network ID or net ID: It identifies the network to which the host is connected. The Network Information Centre is assigned the network id.

ii. host ID: It identifies network connection to the host rather than actual host itself. The local network administrator assigns the host id. There are five classes of IP addresses as given below:

IPv4 classes:

There are mainly five type Ipv4 classes:
1. Class A: It’s address range – to
2. Class B: Its address range – to
3. Class C: It’s address range – to
4. Class D: It’s address range – to
5. Class E: It’s address range – to


The original Ip addressing scheme has a few drawbacks. For example, in the case of a large class B system having 64000 hosts, it is difficult for the local administrator to manage all the hosts, especially if they form a network of small networks.

If a problem arises out of a particular IP then it becomes necessary for the administrator to identify the physical location of the machine holding the IP. So, there should be some technique that can identify the physical location of the machine just by getting the IP address of it. Subnet Addressing concept introduces to solve this problem.

Now, it should be clear that the IP address range provided to an organization has a fixed net ID. So, the IP addresses of all the machines of that organization have the same net ID. What varies between them is the host ID part. Subnetting means the physical clustering of the machine within the organization. Subnet Addressing means providing a specific address to each of the subnets.