You are the network administrator and are given the tasks to plan for the future expansion of the network. You decide to subnet the current network of 172.15.0.0. What will be the subnet mask be if every subnet has to allocate 500 hosts.

Explanation: The requirement of having to allocate 500 hosts on each subnet can be achieved by the following: 2^9 = 512. So deducting the broadcast and network address we have 510 possible hosts on each subnet. We used 9 bits to allocate the hosts, this leaves us 7 bits for possible subnets. Those 7 bits in binary is 1111 1110 or 254 in decimal.