I don't think CIDR has anything to do with this. If you had a class B network, were you required to segment it into class C's? no, right? so, same problem, it's

I don't think CIDR has anything to do with this. If you had a class B network, were you required to segment it into class C's? no, right? so, same problem, it's not clear what are your network and broadcast addresses without knowing your class, same as not knowing your cidr /n if you are "inside" your network, you have the mask; if you are outside, you don't know. yes, if you are inexperienced and have never seen anything but class C, you might not make allowances for class B etc. The real problem with trying to solve these problems is we not allowed to deploy LARTs any more, or clue-by-fours.