Subnet
Also known as: Subnetwork · IP Subnet
A subnet is a defined range of addresses within an IP network, marked off by a subnet mask.
A subnet divides a larger IP address space into smaller, clearly bounded ranges. Devices within the same subnet can talk to each other directly, without a router forwarding the traffic. A subnet is defined by its subnet mask or CIDR notation, such as 192.168.10.0/24 for 256 addresses.
In practice, each site, floor or area of a business often gets its own subnet — for example 192.168.10.0/24 for the office and 192.168.20.0/24 for production. Devices use the subnet mask to work out whether a destination sits in the same range or needs to go through the gateway. The size of a subnet sets how many devices can fit in it at once.
A common mistake is choosing a subnet that's too small, which runs out of room the moment new devices — cameras, printers, IoT sensors — get added. Subnets and VLANs are also frequently confused: a VLAN separates traffic at the network level, while a subnet is the IP addressing logic behind it — the two usually go together but aren't the same thing.
What it means in practice
For a business, this means proper subnet planning prevents addresses running short every time a device is added, or network ranges overlapping unnecessarily. The gap in planning usually only shows once a new site or machine can't get a free address. NDVDL lays out this structure during network planning so it can grow with the business.
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