We are going to start getting into subnetting. But before I actually start describing you what is, how to, something that we need to tell you a few bits of information, to kind of help you understand what in the world you’re doing. Because one of the things that happened to me when I was learning what subnetting is, I was told how to subnet, I was told all the math and stuff involved and I could mimic the numbers but I didn’t really understand why I was doing it and what was the purpose. You know why would anybody want to do this. So I think it’s very important to get the point across as to what subnetting is and why you would even want to do it to begin with. So I got a couple questions here that I want to answer for you.

The first one says why we want to subnet a network.

And the second one is what is subnetting. I mean just what is subnet essentially.

Networking is an investment in your business. It takes time and when done correctly can yield great results for years to come.

Diane Helbig


What is subnetting

Let’s do the second question first. Subnetting the word subnet is short for sub network. So in essence what you have is – you have a network that you’re going to be working on think of it as like your company’s network, the business you work for. You have a network that runs your company and what you want to do is, you want to take that network and you want to break it into smaller pieces. You want to create what’s called sub networks. It’s a sub network of your overall network. So subnetting is in essence is breaking something down into smaller pieces.

And the easiest way that I think that can explain this is considering, everybody’s ordered a pizza before and everybody’s had a pizza delivered to their house, or went and got a pizza somewhere. If you think about it when you purchase a pizza, you purchase one whole pizza. And when you open the box the pizza is right there. it’s round assuming it’s round somewhere. Can be square I know but it’s round and it is one whole pizza you bought. But you don’t eat the whole pizza, not at least in one sitting. What you do is, you eat the pizza in slices. So in essence they take that one whole pizza and they chop it up into smaller pieces that is easier for you to eat. But how many pizzas do you have? You still have one. You have one pizza that’s broken into smaller pieces to make it easier for you to manage.

What is Subnetting

If you handle well this is the same concept, the exact same concept for subnetting. You have one network, one whole network that you’re going to break down into smaller pieces, so that you can manage the network easier and you can organize things better.

And in fact that leads us into the top question up here, which is : why do you want something that a network benefits and what is the reasoning behind doing this other than it’s on a test it’s a book. You know why would you want to do this? Well there are three basic reasons.

Reasons why you want to subnet a network.

There are three main reasons why you would want to subnet a network.


Security is huge in the world today. You see it on the news all the time. There are you know terrorist attacks, there are all sorts of hacking going on. So security in general is very important. And your network security is also very important. You have a lot of information, a lot of data stored on your network that you do not want people to get access to. It can be anything from personal records to a top-secret project that your company is working on, that you just don’t want to fall into the wrong hands.


Another thing that you need is organization. You’re organizing your network, you can take each piece of your network and you can assign it to a particular division or particular department within your company. For instance you can take one slice here and put everyone in your company that’s in say Human Resources. They might be in this slice and only Human Resources be in that slice whereas the very next one it might be your Salesforce and only your Salesforce. Next could be just your IT department and so on and so on.


You know really the possibilities are endless so you can organize your network. And by organizing your network with people that have like jobs, allow you to secure the network better. I’ll explain that more in just a minute.


And the next thing that subnetting gives you is performance. Smaller networks tend to be faster networks. So you have the ability to increase network performance by isolating each one of these networks away from each other, and it can make your network run a little bit faster.

Now the security, the organization and the performance this all comes from again taking your one whole network here and breaking it into smaller pieces.

Now the way this really works and the way that this functions so well is from use of one network device that you should already have a little bit of experience with and that network device is called a router.


A router is a network device that has one function in life, or I should say one main function in life, and that function is to connect different networks together. Well what signifies a different network? A different network is signified by its network ID.

You can get the idea about the network ID from my other post which you can check here.  


How router works

So a router takes the different area codes or the different network IDs and allows them to connect together, allows them to talk. So in essence if we take our little pizza analogy here and we take each slice as a sub Network or a small piece of our overall network, if we were to put a router here in the middle. So we make a router go in the middle. We can allow all these other networks to talk to one another. But the beautiful thing is that since we’re the network administrator we control this router. Which means that we control all access from one network to another network. If we don’t want certain people to access human resources they won’t, because we will block them. If we want to give them access we can. The cool part about this is that you have what’s called a single point of administration.

So you can administer the router, no matter how many people you have out here on the network. Those people must go through your router to get to another location. Therefore if I manage this one router, if I manage this one place, everyone to go from one network to another must go through here and then over there. So I could manage that they have to go through me. It’s a wonderful thing that gives us our security obviously.

We could break things down by organizing our departments or organizing our divisions within our company. Each division or each department has its own sub Network and then the performance increases usually. These are smaller pieces of the overall pie. So the smaller piece gives us a little bit better performance.

So this is what subnetting is. The basics of what subnetting is as well as you know why you would want to do this.