Subnetting is the *subdivision of a network into logical groups* called subnets. It works like a network inside a network. Subnetting divides up a network address range into smaller subnets within the network. These smaller subnets form based on the IP addresses and network mask of the devices on the network. Subnetting creates a network of devices *to function as their own network*. This makes the network more efficient and can also be used to create **security zones**. If devices on the same subnet communicate with each other, the switch changes the transmissions to stay on the same subnet, improving speed and efficiency of the communications. Uses [[Classless Inter-Domain Routing|CIDR]] ### Security benefits of subnetting Subnetting allows network professionals and analysts to create a network within their own network without requesting another network IP address from their internet service provider. This process uses network bandwidth more efficiently and improves network performance. Subnetting is one component of creating isolated subnetworks through physical isolation, routing configuration, and firewalls.