What Is Variable Length Subnet Mask (VLSM)?

VLSM is like your old friend who always wears a mask. He's the one who comes to all of your parties, but people need to learn his real name. He's the one who helps you out when you're in trouble, but nobody knows where he lives. He's the one who keeps you safe and happy, but no one knows how it looks. VLSM is just like that guy—except it's not a guy. VLSM is a mathematical concept network administrators use to manage their IP addresses. It allows them to assign different masks to different sections of their networks based on how many hosts they want in each area and how much space they have available for IP addresses. VLSM also has some other names: classless Internet Protocol (IP) address, subnetting with variable length subnet masks (SVLSM), and network prefixes with variable length subnetting (NPVS). VLSM is a clever way to create IP addresses that can assign to a network in a very space-efficient way. It uses subnet masks of varying lengths, not just for routers! VLSM, or Variable Length Subnet Masking, is a way of dividing your network's IP addresses into smaller groups. It can help you create more efficient routing and save on costs. Like FLSM (Fixed Length Subnet Masking), VLSM divides IP addresses into subnets based on the subnet mask. The difference is that instead of assigning an actual IP address to each group of hosts, as with FLSM, VLSM gives only part of an address. For example, suppose you were using a class C network (192.168. 0. 0/16) and wanted to divide it into two subnets instead of assigning 192. 168. 0 through 192.168. 255 to one subnet and 192. 168. 1 through 192. 168.254 to another subnet. In that case, you could give just 192 through 191 to one subnet and 192 through 191 plus 1 to another subnet—saving on costs by not having to buy new IPs for each new host device added to those subnets later on down the road! Another benefit of VLSM is that it simplifies assigning IP addresses for networks.