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What will that cost be?

Examine the following diagram:

While troubleshooting an OSPF routing problem, you need to determine the cost for Router F to reach the
192.168.5.0 24 network via the best route.
What will that cost be?

PrepAway - Latest Free Exam Questions & Answers

A.
110

B.
2

C.
3

D.
7

Explanation:
The best route to the 192.168.5.0/24 network from the perspective of router F will have an OSPF assigned cost
of 2. There are three possible loop-free paths to get from router F to the 192.168.5.0/24 network. The default
OSPF costs for a 100 MB link, a T1 link, and a T3 link are 1, 64, and 2, respectively.
The three paths and the calculation of their costs are shown:
Router F to Router E to Router A: 1 + 1 = 2
Router F to Router C to Router A: 2 + 1 = 3
Router F to Router B to Router D to Router C to Router A: 64 + 64 + 64 + 1 = 193
Each OSPF route calculates the cost of its path to a network, and passes that value on to the next router, which
will then add to it the cost to reach that neighbor. For example, the routing table of Router E would look like this
for the route to 192.168.5.0/24:
O 192.168.5.0 [110/1] via <output omitted>Router F would add its own cost to reach Router E to the cost of reaching 192.168.5.0/24, resulting in the
following output:
O 192.168.5.0 [110/2] via <output omitted>
110 is the administrative distance of OSPF.
Objective:
Routing Fundamentals
Sub-Objective:
Configure, verify, and troubleshoot single area and multi-area OSPFv2 for IPv4 (excluding authentication,
filtering, manual summarization, redistribution, stub, virtual-link, and LSAs)

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One Comment on “What will that cost be?

  1. ccnaa says:

    ok something is not right here. In link state cost counting (ospf) we have to count in the link not just form router to router but the link to the network as well. So if to think that link to 192.168.5.0/25 is 100Mbps so link cost is 1 so from rtrF to rtrE is 1 from rtrE to rtA 1 so 1+1+1 is 3
    The right answer should be 3




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