Well, that is it for the quick review, so let's go ahead and start on Variable Length Subnet Masking (VLSM). It came into existence for the simple reason that IPv4 public addresses were running out. In the past, when companies purchased public IP addresses (let's say they only needed 1,000 IPs), they would give them a whole Class B address range, which can handle 65,534 IP addresses. They quickly found out that it was not the correct practice to follow.
So, what did the Internet Assigned Numbers Authority (IANA) and service providers do to fix this issue? VLSM. Now you can move the prefix line or subnet mask to the appropriate number of IP addresses needed for that segment. VLSM has some rules, which are as follows:
- You must start with highest number of IP addresses
- They should be in a continuous order
- The networks should start with an even number...