300-510 · Question #163
Refer to the exhibit. An engineer is troubleshooting a networking issue with several symptoms. The shortest path from router R1 to R8 is underused and the longest path is overused. Traffic from…
The correct answer is C. Configure a Level 2 IS-IS domain on router RI. In IS-IS, a Level 1 (L1) router only has visibility into routes within its own area. When an L1 router needs to reach a destination in another area, it uses a default route pointing to the nearest L1/L2 (L1L2) router - not necessarily the topologically optimal path. This…
Question
Refer to the exhibit. An engineer is troubleshooting a networking issue with several symptoms. The shortest path from router R1 to R8 is underused and the longest path is overused. Traffic from 10.1.1.1 to 10.8.8.8 is routed on the longest path. Traffic between the R1 and the application server is experiencing packet drops and latency problems. Which action resolves the issue?
Exhibit
Options
- AConfigure route leaking for the IP address Of the application server on router RI.
- BIncrease the RI to R2 link metric to 20.
- CConfigure a Level 2 IS-IS domain on router RI.
- DBlock the advertisement of the application server IP address to router R6.
How the community answered
(37 responses)- A3% (1)
- B11% (4)
- C81% (30)
- D5% (2)
Explanation
In IS-IS, a Level 1 (L1) router only has visibility into routes within its own area. When an L1 router needs to reach a destination in another area, it uses a default route pointing to the nearest L1/L2 (L1L2) router - not necessarily the topologically optimal path. This 'closest exit' behavior causes suboptimal routing: traffic may follow the longest path because that L1/L2 router happens to be closer within the local area. By configuring R1 as a Level 2 (L2) router, it gains full L2 topology knowledge of all areas and can select the true shortest path to R8 (10.8.8.8). This resolves both the underutilized shortest path and the packet drops/latency caused by congestion on the suboptimal longer path.
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