Cisco CCNA – IP address Class A range
CLASS A RANGE:
Network bits available ( x ): 0xxxxxx
Networks: 8 bits. First bit from the network must by 0 so it give us 7 bits to play with. The number of networks which can be created is therefore 2^7 which is 128. However IP address 0.0.0.0 is used as a default gateway and 127.0.0.1 is used as a loop back. Therefore, we need to subtract those 2 addresses which gives as 126:
NETWORKS RANGE: 1- 126
Hosts: 24 bits ( 3 bytes ) can create 2^24 = 16,777,216 hosts in the single network. However we can not use a IP address of all host bits turned off for example 10.0.0.0 which is a network ID and furthermore we can not use a address which has all hosts bits turned on for example 10.255.255.255 which is a broadcast address. So the valid range for class a hosts is ( ( 2^24 ) -2 ) = 16,777,214
Filed under: Cisco CCNA Preparation