Up Until now we have just assumed you were getting IP addresses for your 1 network. But what if you have more than 1 network?
To accomodate this we need to break the block of addresses you get into 2 or more smaller blocks (or subnets)
Engineering in Building 1
Sales in Building 2
Support in Building 3
192.168.20.0 / 24
192.168.20.0 / 26
192.168.20.64 / 26
192.168.20.128 / 26
192.168.20.192 / 26
So, why do I have 4 ranges of addresses, when I have only 3 Networks and why are they /26 addresses when I was given a /24?