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RCODE e SERVFAIL
RCODEs and SERVFAIL
The response code (RCODE) gives a broad outcome, not always a root cause. NOERROR means the query completed successfully, even when the requested type has no data. NXDOMAIN says the name does not exist. REFUSED means a server declined the query under its policy. SERVFAIL means the server could not complete it.
SERVFAIL can result from an unreachable authority, a validation failure, or another resolver problem. It does not by itself prove that the name is missing or that a policy blocked it. Compare the same query through a trusted resolver and directly against the relevant authorities, then inspect DNSSEC status and network reachability.
For each observation, record the queried server, name and type, time, RCODE, and whether the reply came from a cache or authority. Avoid changing several records before identifying which component failed.
Check your understanding
Choose the best answer. This quiz runs locally and sends no DNS queries to real domains.
What does SERVFAIL prove by itself?