Question 110
An OSPF customer edge announces a route into an area with multiple ABRs. Observed: Two ABRs forward the same prefix via different areas and traffic becomes asymmetrical. After the correction, which result would most convincingly show that this fault is resolved?
Explanation
Correct Answer
After remove the unintended interarea leak and verify area summaries and route preferences, inspect whether both directions use stable documented paths without unexpected duplicate interarea reachability. This closes the loop between the reported observation (Two ABRs forward the same prefix via different areas and traffic becomes asymmetrical) and the underlying issue (An interarea route leaking policy introduced competing origin and preference paths).
Incorrect Answers
This result is useful in another case with evidence The adjacency stays in ExStart after a router replacement with a different interface MTU. It does not test recovery from two abrs forward the same prefix via different areas and traffic becomes asymmetrical. Check instead whether both directions use stable documented paths without unexpected duplicate interarea reachability.
That observation would verify a separate fault involving conditional default origination depends on a qualifying default route that is absent. Its symptom is Customer routing devices receive no default after the provider loses upstream connectivity. For this case the actual issue is an interarea route leaking policy introduced competing origin and preference paths, and the relevant success signal is Both directions use stable documented paths without unexpected duplicate interarea reachability.
It confirms an unrelated service correction: OSPFv3 protocol adjacency and IPv6 address-family enablement were not implemented. The present case reports Two ABRs forward the same prefix via different areas and traffic becomes asymmetrical. Its completion test is Both directions use stable documented paths without unexpected duplicate interarea reachability.