- A bit combination which identifies which portion of an IP address corresponds to the network or subnetwork, and blocks out the rest. For example, a network may use the same values in the first three address fields of a four field address such as WWW.XXX.YYY.ZZZ, and block out, or mask, all but the ZZZ portion, since it is the only one that will vary. Its abbreviation is subnet mask. Also spelled sub-network mask. Also called address mask, or network mask.
- abbreviationsubnet mask