After doing CCNA Virtual Lab Titanium, it graded me wrong because of incorret wildcard configration in the OSPF Practice Scenario.

It expected the following commands:

Enter configuration commands, one per line. End with CNTL/Z
MANUFACTURING(config)#router ospf 100
MANUFACTURING(config-router)#network area 0

I understood how to reach number 3 in the last octet (256-Block Size - 1) but I re-read the book and it is not clear for me what it means.What does exactly number 3 tell us?

Network is , host range and 10, broadcast I sincerely did not understand what informatio number 3 matches.

I read Cisco Press book (Odon) and he does not mention such configuration.

Thanks in advance.