In classful IPv4 addressing, which class would you use for networks with many hosts per network?

• A. Class A
• B. Class B
• C. Class C
• D. Class D

Answer: (A)

In classful IPv4 addressing, how many devices you can put on a single network depends on how the 32 bits are divided between the network part and the host part. For networks with many hosts, you want a large host portion. Class A reserves 8 bits for the network and leaves 24 bits for hosts, which gives up to 2^24 minus 2 usable addresses on one network (16,777,214). That is the largest host pool available in classful addressing, making Class A the best fit for networks with many hosts per network. By comparison, Class B allows 65,534 usable hosts per network, Class C allows 254, and Class D is for multicast rather than unicast host addressing.