Just wanted to share a little fast cheat for figuring out the wildcard mask for networks!
The wildcard mask is used some places in IOS, for example in the network command in configuration of the OSPF routing process.
To figure out the network wildcard mask, just take each octet in the netmask and subtract it from 255.
For 255.255.255.0 the wildcard mask will then be 0.0.0.255
For 255.255.255.252 the wildcard mask will be 0.0.0.3 (255 – 252)
Makes work go faster !
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[...] This will limit VTY access to 10.0.0.0/8 and 192.168.0.0/16, the netmask is a Cisco wildcard mask, troubles figuring them out? Try the wildcard cheat. [...]