5.1. Working with Subnets and Subnet Masks

Subnets divide one network into multiple smaller networks, normally interconnected by network devices called routers. (See Chapter 7 for more about routers.)

Not every network environment requires subnets. For example, if your organization's network has 254 or fewer hosts — and the network lives in one building (what a concept), there's no reason to subnet it. But if your organization's network expands into multiple locations, the network administrator needs to look at a couple of options: