SUBNETS AND VLANS

When you want to divide a physical network up, each separate part is known as a subnet. You can identify which subnet a device belongs to by the first three numbers in your IP address—for example, 192.168.0. Networked devices can only see other devices on the same subnet, so a device with an IP address of 192.168.0.2 can see another device on the same physical network with an IP of 192.168.0.3. It cannot, however, see one with the IP address 192.168.1.3, because 192.168.1 is a separate subnet.

VLANs work in a different way—instead of carving up the network into different subnets, they insert a tag or “magic packet” into network traffic sent to and from the VLAN, ensuring it’s filtered accordingly.