What/Why is IP Subnetting/VLSM? Not How

[asdaqamin]

Guy I want to know about IP Adreesing/VLSM.

Recently I have an interview. & ask about the same question. But I only answered the HOW part not WHAT & WHY.or you say any peoper defination.

I have also searched on net after that but not found WHAT & WHY part.

As I know How to do on paper all about that.

[Jon Marshall · Accepted solution]

Hi

What is VLSM = the ability to apply different subnet masks to the same major network rather than having to use the same subnet mask.

WHY = because without VLSM you can have very inefficient address allocation eg.

192.168.5.0/24

You need a subnet that allows for 60 hosts and a subnet for a point to point link.

Without VLSM

60 host subnet = 192.168.5.0/26 or 255.255.255.192.

P2P link wher you only need 2 IP addresses =

192.168.5.64/26

And you have wasted 60 addresses.

With VLSM

192.168.5.0/26

192.168.5.64/30

Jon