Connectivity & Networks
Subnet mask
A setting that tells an IP device which addresses are considered local to its network.
IN ONE SENTENCE
It helps the device decide whether to communicate directly or through a router.
In normal English
Two devices can have valid-looking IP addresses but still fail to communicate if their subnet configuration does not match the network design.
Why would I use it?
Use it whenever configuring static IP networking.
THINK OF IT LIKE…
The boundary line showing which network neighbours live on your street.
Related terms
IP address, gateway address, TCP/IP
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