What is class A range?

A Class-A network is a network with a subnet mask of 255.0.0.0 or /8, and the official Class A range runs from 1.0.0.0/8 to 127.0.0.0/8.

This is over half the total addresses that can be assigned in the entire IPv4 address space, because although 10.0.0.0/8 (dedicated to private networks) and 127.0.0.0/8 (dedicated to loopback interfaces) cannot be otherwise used, the slices taken out of the other half are larger.