What is the purpose of a subnet mask?

The primary purpose of a subnet mask is to divide a network into smaller subnetworks, or subnets. This division allows for more efficient use of IP address space and can help improve network performance and security. When a subnet mask is used in conjunction with an IP address, it determines which portion of the address refers to the network and which part refers to the specific device (or host) within that network.

By utilizing subnetting, organizations can create multiple logical networks within a single physical network, enabling better organization of devices and reducing broadcast traffic. This is especially useful in larger networks where the number of devices can overwhelm the local broadcast domain.

In practical terms, a subnet mask works by applying a binary operation to the IP address, enabling routers and devices to interpret addresses correctly within the context of the divided subnets. Overall, subnetting helps organize network structures and makes routing more efficient, which is essential in modern IP networking.