FLSM and VLSM – Part 1

After many requests to extend the Subnetting Mastery video series, I am adding an appendix which will cover Fixed Length Subnet Masks (FLSM) and Variable Length Subnet Masks (VLSM).

This is Part 1, which teaches how to answer questions of this variety:

• If you start with a /18, what size sub-network would you need to create 100 sub-networks?
• If you start with a /21, how many sub-networks could you create that could contain 50 IP addresses?

In this video, we’ll teach you about the Network Doubling logic, and how to simplify the questions above, and easily come to the correct answer. Then we’ll discuss the difference between FLSM questions and VLSM questions.

Finally, we’ll show you 2^N notation, which uses a Powers of 2 table to quickly answer questions like those above.

The next video in the series will dive deeper in to VLSM.

Every video in the Subnet Mastery series as well as an IPv4 Subnetting Problem Generator is available here:

Enjoy!

Related Posts:

FLSM and VLSM – Part 2

Wildcard Masks

Discontiguous Wildcard Masks

Classful vs Classless vs CIDR vs FLSM vs VLSM