BSCI Exam Cram™ 2 (Exam 642-801)

Using VLSM to Extend the IP Addresses Scheme

As IP subnets have grown, administrators have looked for ways to use their address space more efficiently and flexibly. One of the resulting techniques is called variable-length subnet masking (VLSM). VLSM is a method of designating a different subnet mask for the same network number on different subnets. Thus, a network administrator can use a long mask on networks with few hosts and a shorter mask on subnets with many hosts. If VLSM is not supported on your routers, your organization is stuck with the prospect of using a single subnet mask for an entire growing Class A, B, or C network. VLSM facilitates a hierarchical design that is more representative of an organization's logical network topology. ...