Refer to the exhibit. A network associate has configured OSPF with the command:City(configrouter)# network 192.168.12.64 0.0.0.63 area 0After completing the configuration, the associate
discovers that not all the interfaces are participating in OSPF. Which three of the interfaces shown
in the exhibit will participate in OSPF according to this configuration statement? (Choose three.)
A.
Serial0/0
B.
FastEthernet0 /0
C.
Serial0/1.104
D.
Serial0/1.103
E.
Serial0/1.102
F.
FastEthernet0 /1
Explanation:
OSPF uses the concept of wildcard masks much like access list filters. OSPF network matches
are done using the network number and wildcard bits. The network number is the network portion
of the IP address, with the host bits all set to zero. The wildcard bits determine which portion of the
address the access list will act on. Only bits set to zero are acted upon (bits set to one are
ignored.) This is the exact opposite of a netmask. Remember that this number is in bits, and you
will always have all zeros to the left of the first one, and all ones to the right of the last zero. The
table below shows some examples of netmasks and wildcard bits.
In this example, the 192.168.12.64 0.0.0.63 will comprise of all interfaces with an IP address in the
192.168.12.64-127 range.
