Question 1

Why does a /26 have 64 addresses but only 62 hosts?

Accepted Answer

The first address identifies the network and the last is the broadcast address, so neither is assigned to an interface.

Question 2

Are classes A, B and C still used?

Accepted Answer

Not for routing. Since CIDR any prefix length is allowed; class names survive as shorthand for /8, /16 and /24.

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