Paul Stewart of PacketU comments:
We cover all sorts of different topics on this site. Today, we are starting a multipart series on subnetting. These concepts are fundamental building blocks for network administrators, engineers and architects. The subnetting topics outlined in this series should be well understood prior to moving into advanced design or configuration topics. Moreover, the underlying technical concepts of this subject should be understood prior to utilizing any shortcuts to calculate subnet addresses and useable address space.
A great introduction to subnets for those that need to brush up on it before taking a networking exam.
Read more at: IP Subnetting Part 1: What is a Subnet?