The "Eight" in the specification
of CIDR 192.0.0.0/8 is showing the fixed state of top eight bits. Every one of the
four octets is 8 bits, so 8 bits fixed shows that the first octet (192) is fixed.
This makes simpler computation, as the remaining 3 octets each represent 1 byte
= 8 bits. Each octet can be presented as 256 exclusive addresses, so we have 3 existing
octets and that is 256 x 256 x 256 = 16,777,216 addresses of
Performing the dilemma in alternate
way, the lowest 24 bits are not fixed and are consequently accessible for
addressing. Then we have 224 = 16,777,216 addresses of network.