Subnetting allows you to create multiple logical networks that exist within a single Class A, B, or C network. If you do not subnet, you are only able to use one network from your Class A, B, or C network, which is unrealistic.
In this course you will learn the necessary information about IP addressing and subnetting
such as how addresses are broken down and how subnetting works. you will learn all necessary information about
subnetting through practical examples which help you answer any questions about subnetting easily and in a very short time.
any one who wants to take CCNA exam need to know how to do subnetting.