Question 70
A provider injects a default route into a customer OSPF domain. Observed: Customer routing devices receive no default after the provider loses upstream connectivity. What evidence would validate recovery from this precise failure mode?
Explanation
Correct Answer
The intended result is Customer default is present only under the permitted upstream condition. It specifically verifies recovery from conditional default origination depends on a qualifying default route that is absent, which produced the original symptom: Customer routing devices receive no default after the provider loses upstream connectivity. It is stronger evidence than a generic interface-up indicator.
Incorrect Answers
That observation would verify a separate fault involving area option bits in hellos do not agree with unchanged internal routers. Its symptom is A neighbor goes down directly after changing only the ABR area mode. For this case the actual issue is conditional default origination depends on a qualifying default route that is absent, and the relevant success signal is Customer default is present only under the permitted upstream condition.
This result is useful in another case with evidence Backup traffic activates before the primary fiber has failed. It does not test recovery from customer routing devices receive no default after the provider loses upstream connectivity. Check instead whether customer default is present only under the permitted upstream condition.
It confirms an unrelated service correction: Type-1 and type-2 external metric semantics were treated as interchangeable. The present case reports Customer routing devices receive no default after the provider loses upstream connectivity. Its completion test is Customer default is present only under the permitted upstream condition.