[happythought]

In the spirit of nitpicking, class A, B, and C referred to specific address blocks, not network sizes. A /24 in the class A range was still class A rather than class C.

[unethical_ban]

I worked on network/firewall at a rather large bank from 2009-2019 and we used the class labels and "slash 24s" etc. interchangeably when talking. Not that you're incorrect, but that the slang was used and everyone knew what people meant by it.

[tptacek]

See, I had no idea. This is the best kind of nitpicking.

[swinglock]

Look up CIDR on Wikipedia, which is what we use now and you know it already, but more so to learn the difference from the old classful networking.

Then you'll never use "Class A/B/C" again. :) It's correct to just say /24 while Class C isn't, because it has a more specific but outdated meaning.

[tptacek]

I'm familiar with CIDR, I just always understood it to mean "arbitrary prefix lengths, not just on byte boundaries".