Subnetting involves modification of an IP network into smaller IP networks which are called subnets.  

In a layman language, Subnetting is a process which involves dividing of a network into smaller networks which are termed as subnetworks or subnets. Every subnet has its own address. Initially, these subnets were designed for resolving the issue of shortage of the IP addresses over Internet.

Subnetting helps in reducing network traffic as well as for concealing network complexity. It is used for reducing the wastage of IP addresses. Subnetting is quite useful as it offers various facilities, some of which are listed below –

·       Low level of LAN security - you can manage each subnet separately by increasing the level of security.

·       Broadcast containment: it reduces collision as each sub-network is a different broadcast domain.

·       Address flexibility: it leads to the minimum loss of the IP addresses.

Subnetting is a basic topic covered during CCNA Course. Remember, it is not a theoretical topic so know the practical implementation of the topic for developing a better understanding.