Subnet Masks

A subnet mask is what we use to assign different amounts of networks and hosts to an IP network. It essentially divides the IP address into two parts: the network and host. This is a trading game- the more hosts you have, the fewer networks you will have. And yet the more networks you have, the fewer hosts you will have. Review the class A default subnet masks as shown below.

The class B network will need to recognize two network portions, and two host portions. This can be seen in the below diagram.

Lastly, we have the class C subnet. It is the most commonly used subnet, so pay special attention to it in the upcoming lecture. You can see a diagram of the default subnet below.