You have been given an IP address network of 213.43.53.0. You are asked to subnet it for 22 hosts per network. What is the subnet mask you will need to use to maximize networks?

The mask you will need to use is 255.255.255.224 (/27). This will allow for 30 hosts per network for a total of 8 networks. The formula for solving for hosts is 2^X – 2 is equal to or greater than 22 hosts, which in this case is (2^5 – 2) = (32 – 2) = 30. So 5 bits are used for the host side, leaving 3 bits for the subnet side. 3 bits + 24 bits (original subnet mask) = /27, or 255.255.255.224.