Hi guys, new forum member here!

I'm currently studying like crazy with the hope of doing an OSCP qualification when I learn enough, but as my question was network related I thought it maybe best to post it here..


I've been following this guide
http://www.infiltrated.net/pentesting101.html

and learning all the essential areas it describes until i get to the following line from the networking part..

"You will need a firm grasp on subnetting. The differences between a Class A, B and C network, and no a Class C is not a slash twenty four (/24). If that came as a surprise to you, then you seriously need to go back and read. "

This has confused me a LOT, from my previous University studies I was lead to believe that a Class C subnet IS slash 24 (/24) as it has 24 of the possible 32 bits active (255.255.255.0) and pretty much everything i've researched has backed that up.. have I missed something obvious here??