Every IP address must be accompanied by a subnet mask. By now you should be able to look at an IP address and tell what class it is. Unfortunately your computer doesn’t think that way. For your computer to determine the network and subnet portion of an IP address it must “AND” the IP address with the subnet you take a single network such as and divide it into five smaller networks (, , , , ) the outside world still sees the network as , but the internal computers and routers see five smaller subnetworks. Each independent of the other. This can only.
