It was for compatibility with classful networks. If you have a class A (/8) network, you could (in principle) treat it as a single network and number all the ma

It was for compatibility with classful networks. If you have a class A (/8) network, you could (in principle) treat it as a single network and number all the machines on it sequentially from 12.1 to 12.16777215. Of course, nobody actually does that anymore. But the parser behavior is still out there because there's the possibility that someone is still using it...