The following output was taken from Router R3. A scan of R3’s configuration shows that no
bandwidth commands have been configured in this router. Which of the following answers
lists configuration settings could be a part of a configuration that results in the following
output? (Choose two.)
R3#show ip ospf interface brief
Interface PID Area IP Address/Mask Cost State Nbrs F/C
Se0/0/0.2 3 34 10.10.23.3/29 647 P2P 1/1
Se0/0/0.1 3 34 10.10.13.3/29 1000 P2P 1/1
Fa0/0 3 34 10.10.34.3/24 20 BDR 1/1
A.
An auto-cost reference-bandwidth 1000 command in router ospf mode
B.
An auto-cost reference-bandwidth 2000 command in router ospf mode
C.
An ip ospf cost 1000 interface S0/0/0.1 command in router ospf mode
D.
An auto-cost reference-bandwidth 64700 command in router ospf mode
Explanation:
Because none of the interfaces have a bandwidth command configured, the
only commands that can influence the OSPF cost are the auto-cost reference-bandwidth
router subcommand and the ip ospf cost interface subcommand. To give the output shown in
the question, either the interface cost could be set directly on all
three interfaces listeD. Alternatively, the reference-bandwidth could be set to cause one of
the interface costs to be as shown in the output, with the other two interfaces having their
costs set directly.
For the wrong answers, the ip ospf cost interface s0/0/0.1 router subcommand doesnot exist—instead, it is an interface subcommand. An auto-cost of 64700, used as the
numerator in the ref-bw/bandwidth cost calculation, does not result in any of the
three listed interface costs.
For the two correct answers, with a default bandwidth of 1544 (Kbps) on the serial
subinterfaces, a reference bandwidth of 1000 (Mbps) implies the math 1,000,000 /
1544, for an Interface cost of 647. With a default bandwidth of 100,000 Kbps
(100 Mbps) on Fa0/0, a reference bandwidth of 2000 (MBps) implies math
of 2,000 / 100 = 20.