When doing any moderate to advanced networking, you are likely to have to deal with subnetting. While some people have an ability to do the binary math in their head to figure out the correct subnet-mask, some may find it difficult to calculate, for them Ipcalc is a tool in Linux which help them to calculate no. of subnets, subnetting mask and other Ip addressing related stuff.Ipcalc takes an IP address and netmask and calculates the resulting broadcast, network, Cisco wildcard mask, and host range. By giving a second netmask, you can design subnets and supernets. It is also intended to be a teaching tool and presents the subnetting results as easy-to-understand binary values.