How do You Determine the Number of Bits Required for Subnetting a Given Network?

Answer: To determine the number of bits required for subnetting a given network we require the number of subnets in which the given network is to be divided. Then, we can easily determine the number of bits required for subnetting a given network by equating the number of subnets required by 2ⁿ. Also, in classful addressing we can determine the number of bits required for subnetting a given network using subnet mask.

First identify the class of IP address and then find the subnet mask of the class. The number of extra bits in the given subnet mask compared to the subnet mask of the class gives the number of bits required for subnetting a given network.

Steps to Determine Number of Bits Required for Subnetting a Given Network

Below are the steps to determine the number of bits required for subnetting a given network.

• First identify the number of subnets in which we have to divide the network.
• Then, equate the number of subnets to be divided to 2ⁿ.
• Find the value of n.
• The number of bits required foe subnetting a given network is n.

Example

Consider we have to divide a network into 15 subnets then find the number of bits required for subnetting the given network.

Solution:

Number of Subnets required = 15
2n = 15
Take the least value of n that can satisfy the above expression 
n = 4
To get number of subnets = 15, the number of bits required for subnetting = 4