Subneting is a process of breaking the network into smaller units. These units care called as subnets. Here a subnet could be several machines in a single LAN. Networks using IP can create sub networks of logical addresses. With every IP address there some of the bits in the machine can be used to identify a specific subnet. The IP address then contains three parts: the network number, the subnet number, and the machine number.

Advantages of using Subneting:-

1. Easier network management and trouble shooting
2. Routing table's size is reduced which means faster network transfers
3. Solves network congestion problems:- Since the complete network is divided into smaller networks
4. Network addresses can be decentralized e.g. the administrator of the network can monitor the subnet .

Subnets that can be customized; i.e. modifying the dividing point between subnet ID and host ID to suit the needs of our network. The subnet mask that we use when creating a customized subnet is, called a custom subnet mask. This custom subnet mask is used to find the customization.

Adding 1 's as a bit means increasing the subnets and decreasing the hosts. Removing or decreasing l' s means decreasing subnets and increasing hosts. Hence by increasing or decreasing the subnet architecture can be decided as per needs.

A subnet mask allows identification of host part and network part of an IP address. Subnet mask can be used to find if an IP address is present on a subnet or not.