[roger_smith]

I think it's worth noting that this is known as classful networking and I'm pretty sure has been obsolete since the mid 90's. Also, class A would technically be from 0-127.

127 range is reserved for loopback and not typically included in the class listing

http://www.vlsm-calc.net/ipclasses.php


While CIDR is basically law of the land these days, you have to understand this foundation to understand subnetting and understand how routers see IP addresses. That was the main point I didn't get to yet and likely will when I'm less tired.