How to Calculate the Subnet IDby Richard Jennings
In computer networking, a subnet is a section of a network that has been partitioned from other subnets, as part of a larger IP network. Subnetting allows a network administrator to logically organize machines and workstations on a network with multiple clients by creating divisions of smaller subnets. The subnet ID identifies the subnetwork that follows the network ID and precedes the host ID, which indentifies users, or clients, of a subnet belonging to a larger network.
Open a subnet calculator in a web browser (see Resources).
Select the network class and enter the IP address.
Select the subnet mask.
Select the number of subnet bits and mask bits.
Select the number of subnets and hosts per subnet. The subnet ID is automatically displayed in the "Subnet ID" field.