Wildcard mask

Common card · No. 430550

A wildcard mask is a mask of bits that indicates which parts of an IP address are available for examination. In the Cisco IOS, they are used in several places, for example: To indicate the size of a network or subnet for some routing protocols, such as OSPF. To indicate what IP addresses should be permitted or denied in access control lists (ACLs). A wildcard mask can be thought of as an inverted subnet mask. For example, a subnet mask of 255.255.255.0 (11111111.11111111.11111111.000000002) inverts to a wildcard mask of 0.0.0.255 (00000000.00000000.00000000.111111112). A wild card mask is a matching rule. The rule for a wildcard mask is: 0 means that the equivalent bit must match 1 means that the equivalent bit does not matter Any wildcard bit-pattern can be masked for examination. 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...

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