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Cisco Wildcard Mask Calculator

Compute Cisco wildcard masks and the OSPF network statement from any network and prefix.

Subnet mask255.255.255.0
Wildcard mask0.0.0.255
IOS statementnetwork 192.168.1.0 0.0.0.255 area 0

How to read the result

Wildcard = inverse of the subnet mask. IOS uses wildcards in network and access-list statements: /24 = mask 255.255.255.0 = wildcard 0.0.0.255.

Example

192.168.1.0/24 → wildcard 0.0.0.255 → network 192.168.1.0 0.0.0.255 area 0

FAQ

What is a wildcard mask?

The bitwise inverse of a subnet mask. 0 bits must match, 255 bits are ignored.

Where do I use the network statement?

Under router ospf: network <net> <wildcard> area 0 advertises matching interfaces.