Summary of Subnetting

You have seen that flexibility has been built into IP addressing via a process known as subnetting , which allows organizations to divide up classful network IDs into a number of other networks. Any device can determine how an IP address is divided by looking at the IP address's subnet mask. This mask indicates which bits have been used for subnetting and which bits are still being used to identify hosts. Of course, each class of IP address has a default mask. Furthermore, we identified some important questions to consider when setting up an addressing scheme. Specifically, you need to know the number of hosts and networks an organization requires in the present and the future.

The ability to do subnet masks on the fly for the CCNA exam is crucial. The good news is that this ability is also crucial to being proficient at networking in general. Therefore, feel good about spending a significant amount of time practicing the art of subnetting.