Hi,

With the network command you only control which interface should OSPF run on (the interface(s) which its IP(s) are covered by the network command), and has nothing to do with the subnet mask of the routes advertised (the routes advertised inherit the subnet mask from the interfaces), and thus its your call how to control the wildcard mask of the network command to control which interface(s) should run OSPF, personally i prefer running the network command with a wildcard of 0.0.0.0 to indicate certain specific interfaces and to be clear in the configuration, and you can also summarize multiple interfaces with one network command, it all depends on your scenario, and as for the exam you can freely either use the 0.0.0.0 wildcard, or just inverse the subnet mask which i saw many people/books do, but i just don't like it as i can't feel its benefit.

HTH,

Mohammed Mahmoud.