What is a subnet, and how does subnetting work?

A subnet, or subnetwork, is a smaller network created from a larger one through a process called subnetting.

Subnetting is a method used to divide a network into two or more smaller networks, each known as a subnet. This is done to improve network performance, enhance security, and simplify management. It involves dividing the IP address into two parts: the network address and the host address. The network address identifies the network, while the host address identifies a specific device (like a computer or printer) within that network.

The process of subnetting starts with an IP address. An IP address is a unique identifier for a device on a network, and it's made up of two parts: the network ID and the host ID. The network ID identifies the network as a whole, while the host ID identifies a specific device within that network.

Subnetting works by taking bits from the host portion of the IP address and using them to create additional network IDs. This is done using a subnet mask, which is a binary pattern that determines how the IP address is divided. The subnet mask has the same number of bits as the IP address, and the position of the ones and zeros in the mask determines the division between the network and host portions of the IP address.

For example, if you have a network with the IP address 192.168.1.0 and a subnet mask of 255.255.255.0, the first three octets (192.168.1) represent the network ID, and the last octet (0) represents the host ID. If you wanted to divide this network into two subnets, you could change the subnet mask to 255.255.255.128. This would give you two subnets: 192.168.1.0 to 192.168.1.127 and 192.168.1.128 to 192.168.1.255.

Subnetting is a crucial aspect of network management. It allows for better organisation, control, and security of a network. By dividing a network into smaller subnets, administrators can control traffic flow, isolate issues, and prevent problems from affecting the entire network.