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Variable Length Subnet Mask

Vangie Beal
Last Updated May 24, 2021 7:58 am
Variable Length Subnet Mask, abbreviated as VLSM, is a means to specify a different subnet mask for the same network number on different subnets. With VLSM, a network administrator can use a long mask on networks with few hosts and a short mask on subnets with many hosts. To use VLSM, the routing protocol must support it.

See also subnet mask.