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Subnet Masking

A subnet, or subnetwork, is a segmented piece of a larger network. More specifically, subnets are a logical partition of an IP network into multiple, smaller network segments. The Internet Protocol (IP) is the method for sending data from one computer to another over the internet. Each computer, or host, on the internet has at least one IP address as a unique identifier.

Subnet explained

Goals of a subnet

Organizations will use a subnet to subdivide large networks into smaller, more efficient subnetworks. One goal of a subnet is to split a large network into a grouping of smaller, interconnected networks to help minimize traffic. This way, traffic doesn't have to flow through unnecessary routs, increasing network speeds.

How Subnets work

Each subnet allows its connected devices to communicate with each other, while routers are used to communicate between subnets. The size of a subnet depends on the connectivity requirements and the network technology employed. A point-to-point subnet allows two devices to connect, while a data center subnet might be designed to connect many more devices.

Each organization is responsible for determining the number and size of the subnets it creates, within the limits of the address space available for its use. Additionally, the details of subnet segmentation within an organization remain local to that organization.


The following example shows the separation of the network prefix and the host identifier from an address ( and its associated /24 subnet mask ( The operation is visualized in a table using binary address formats.

  Binary form Dot-decimal notation
IP address 11000000.00000000.00000010.10000010
Subnet mask 11111111.11111111.11111111.00000000
Network prefix 11000000.00000000.00000010.00000000
Host identifier 00000000.00000000.00000000.10000010