Refer to the exhibit.
The network is converged. After link-state advertisements are received from Router_A, what
information will Router_E contain in its routing table for the subnets 208.149.23.64 and
208.149.23.96?
A.
O 208.149.23.64 [110/13] via 190.173.23.10, 00:00:07, FastEthernet 0/0 O 208.149.23.96
[110/13] via 190.173.23.10, 00:00:16, FastEthernet 0/0
B.
O 208.149.23.64 [110/1] via 190.172.23.10, 00:00:07, Serial 1/0 O 208.149.23.96 [110/3] via
190.173.23.10, 00:00:16, FastEthernet 0/0
C.
O 208.149.23.64 [110/13] via 190.172.23.10, 00:00:07, Serial 1/0 O 208.149.23.96 [110/13] via
190.172.23.10, 00:00:16, Serial 1/0 O 208.149.23.96 [110/13] via 190.173.23.10, 00:00:16,
FastEthernet 0/0
D.
O 208.149.23.64 [110/3] via 190.172.23.10, 00:00:07, Serial 1/0 O 208.149.23.96 [110/3] via
190.172.23.10, 00:00:16, Serial 1/0
Explanation:
Router_E learns two subnets subnets 208.149.23.64 and 208.149.23.96 via Router_A through
FastEthernet interface. The interface cost is calculated with the formula 108 /Bandwidth. For
FastEthernet it is 108 / 100 Mbps = 108 / 100,000,000 = 1. Therefore the cost is12(learned from
Router_A)+ 1=13for both subnets – B is not correct. The cost through T1 link is much higher than
through T3 link (T1 cost = 108 / 1.544 Mbps = 64; T3 cost = 108 / 45 Mbps = 2) so surely OSPF will
choose the path through T3 link -> Router_E will choose the path from Router_A through
FastEthernet0/0, not Serial1/0 – C & D are not correct. In fact, we can quickly eliminate answers B, C
and D because they contain at least one subnet learned from Serial1/0 – they are surely incorrect.