This document outlines 5 IP address classes (A, B, C, D, E) including their address ranges, private address ranges, reserved addresses, subnet masks, number of possible networks, and number of host addresses. Class A networks have a default subnet mask of 255.0.0.0 and support up to 128 networks with over 16 million hosts each. Class B networks use 255.255.0.0 and have 65,534 networks with up to 65,534 hosts. Class C supports the most networks, over 2 million, but only supports 254 hosts each.