In the days before CIDR (Classless Internet Domain Routing), networks were commonly organized by classes.
Which of the following would have been true of a Class C network?

A.
The first bit of the IP address would be set to zero.

B.
The first bit of the IP address would be set to one and the second bit set to zero.

C.
The first two bits of the IP address would be set to one, and the third bit set to zero.

D.
The first three bits of the IP address would be set to one.

Explanation:
Class C was defined with the 3 high-order bits set to 1, 1, and 0, and designating the next 21 bits to number the
networks. This translates to the IP address range of a class C network of 192.0.0.0 to 223.255.255.255.Incorrect Answers:
A: Class C was defined with three fixed bits, not just one single bit.
B: Class C was defined with three fixed bits, not just two bits.
D: Class C was defined with the first bits set to 1, 1, and 0. Not to 1, 1, and 1.

https://en.wikipedia.org/wiki/Classful_network