Given an IP address of 172.16.0.0, which subnet mask below would allow us to divide the network
into the maximum number of subnets with at least 600 host addresses per subnet?

A.
255.255.240.0

B.
255.255.224.0

C.
255.255.248.0

D.
255.255.252.0

Explanation:
The last two octets of this class B address, 252.0, gives us binary: 11111100.00000000. The six
subnet bits give us 62 (26 -2) subnets, each with 1022 (210 -2) hosts, which allows us to have the
maximum number of subnets with almost double the required host addresses. *, 224.0, is
11100000.00000000 binary, which gives us six (23 – 2) subnets with 8190 (213 -2) hosts each. *
240.0, is 11110000.00000000 binary, and gives us 14 (24 -2) subnets each with 4094 (212 -2) hosts. *
248.0, is 11111000.00000000 binary, which creates 30 (25 -2) subnets with 2046 (211 -2) hosts.
Many books give detailed descriptions of IP subnetting.