Wildcard mask

A wild card mask is a matching rule.

For example, a wildcard mask of 0.0.0.254 (00000000.00000000.00000000.111111102) applied to IP address 10.10.10.2 (00001010.00001010.00001010.000000102) will match even-numbered IP addresses 10.10.10.0, 10.10.10.2, 10.10.10.4, 10.10.10.6 etc.

Same mask applied to 10.10.10.1 (00001010.00001010.00001010.000000012) will match odd-numbered IP addresses 10.10.10.1, 10.10.10.3, 10.10.10.5 etc.

A network and wildcard mask combination of 1.1.1.1 0.0.0.0 would match an interface configured exactly with 1.1.1.1 only, and nothing else.

For example, when two affected hosts fall in different subnets, the use of a wildcard mask will group them together.