Subnetting is all about modifying the subnet mask in order to create smaller networks $($subnets$)$ from one large network.

Given a network address and a subnet mask:

Determine the number of subnets needed. $($In this case, it was given to you. Other times, you will look at a layout.$)$

Determine how many host bits you need to borrow from the original subnet mask

Determine the new subnet mask, and then determine the increment.

Determine the subnet address for each subnet..

Determine the broadcast address for each subnet.

Determine the range of usable host IP Addresses for each subnet

Determine the IPv$4$ Address of the First Host on this Subnet.

Determine the IPv$4$ Address of the Last Host on this Subnet.

Determine the number of hosts per subnet