IP Subnetting Part 1: What is a Subnet?
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.
So the question I ask today is–
What is a Subnet?
If I asked this as a multiple choice question, which one of the possible answers would you choose?
- In OSI terms, the layer under the network layer–also known as the data link layer.
- A subset of a Classful Network
- 255.255.255.192
- 192.168.1.0
If you chose answer B, you are correct. A subnet is a subset of a Classful Network. So the next logical question is, “What is a Classful Network?”
As we answer these questions, we will use “Classful Network” and Network interchangeable. As we move to discussions about subnets, we will explicitly address them as such.
Classful Networks, in TCP/IP terminology are outline in RFC791. It specifically states the following–
Addresses are fixed length of Continue reading