Question 670
A carrier introduces a shared services VRF for centralized DNS. Observed: Customer VRFs can reach shared DNS but also import other tenants' direct routes. What evidence would validate recovery from this precise failure mode?
Explanation
Correct Answer
The intended result is Only the shared DNS prefixes traverse service VRFs and tenants stay isolated. It specifically verifies recovery from the shared-services exchange uses transit rts that permit uncontrolled customer-to-customer reachability, which produced the original symptom: Customer VRFs can reach shared DNS but also import other tenants' direct routes. It is stronger evidence than a generic interface-up indicator.
Incorrect Answers
It confirms an unrelated service correction: The VPN import policy modifies best-path attributes inconsistently. The present case reports Customer VRFs can reach shared DNS but also import other tenants' direct routes. Its completion test is Only the shared DNS prefixes traverse service VRFs and tenants stay isolated.
That observation would verify a separate fault involving mp-bgp control-plane reachability is out of sync with mpls transport forwarding. Its symptom is VPN route remains active at PEs despite loss of the underlying labeled transport. For this case the actual issue is the shared-services exchange uses transit rts that permit uncontrolled customer-to-customer reachability, and the relevant success signal is Only the shared DNS prefixes traverse service VRFs and tenants stay isolated.
This result is useful in another case with evidence The new VRF learns only one existing site after provisioning. It does not test recovery from customer vrfs can reach shared dns but also import other tenants' direct routes. Check instead whether only the shared DNS prefixes traverse service VRFs and tenants stay isolated.