subnet - Are Cisco admins expected to understand classful networks?

While studying for the CCENT exam, my reference materials have made an alarming number of references to class A/B/C networks. Thankfully they just treat Class A/B/C as shorthand for /8, /16, and /24 CIDR subnets, and don't make any mention of an implicit subnet from the first nibble. Still, it throws me off to have "Class B" pop up in a question or explanation and have to remind myself at every step that there is an implied /16 mask in there.

Is this a convention that is still widely used despite being obsoleted over two decades ago? Am I going to just have to get used to this from my senior admins? And, perhaps most importantly, does Cisco expect its certified technicians/associates/experts to accept and use classful network terminology?
(Ignore the last question if it violates Cisco's exam confidentiality policy.)

Update: After switching to a more authoritative reference/study guide, it became clear that Cisco expects knowledge of actual classful networks, insofar as the official study guide dedicates several chapters to them. This makes the question less about the A/B/C terminology and more about if/why admins are expected to know about classful networks.

Answer

You should know three things about class-based-routing:

• Class-based routing was a simpler system that was abandoned (in 1993) long before most people ever heard about the Internet. In all likelihood, nobody you will ever know has used it. And if any of your network equipment is that old, you should seriously consider alternate employment. The system used the first few bits of the address to determine its class, and (indirectly) its netmask. Note that the netmask was implied in the class, it did not determine the class. Saying you have a "Class C at 172.16.1.0" will earn you a swift kick from anyone with even a vague understanding of class-based routing.




• People currently say Class A, B, and C to mean /8, /16, and /24 netmasks, respectively. As should be obvious from the above, they do so incorrectly. They typically think it makes them appear knowledgeable and wise to the history of of the Internet (oh, the irony).




• Some hold-overs of the original system still exist. "Class D" (prefix 224 to 239) is still multicast, and "Class E" (prefix 240 to 255) is still "Reserved" or "Experimental". Plus, some (older) systems assume a default netmask based on the original class designation; so /8 for prefix 0 through 128, for example. This is often more annoying than helpful, but that's where it came from.