DNS 2 SERVFAIL vs 8 NXRRSET
Both DNS 2 (SERVFAIL) and 8 (NXRRSET) belong to the DNS Response Codes (RCODEs) category. 2 indicates that server failure. The name server encountered an internal error while processing the query. Meanwhile, 8 means that rR Set that should exist does not. A required resource record set is missing from the zone.
Descrição
Server failure. The name server encountered an internal error while processing the query.
Quando você o vê
The recursive resolver could not get an authoritative answer — commonly caused by DNSSEC validation failures, unreachable upstream nameservers, or misconfigured zones.
Como corrigir
Try a different resolver (e.g., 8.8.8.8 or 1.1.1.1) to isolate the issue. If you control the zone, check DNSSEC signatures, SOA serial consistency, and nameserver reachability.
Descrição
RR Set that should exist does not. A required resource record set is missing from the zone.
Quando você o vê
A DNS UPDATE prerequisite expected a certain RRset to exist (e.g., an MX record), but the zone does not contain it.
Como corrigir
Create the missing RRset in the zone before retrying the update, or change the prerequisite to not require its existence.
Diferenças principais
DNS 2: Server failure. The name server encountered an internal error while processing the query.
DNS 8: RR Set that should exist does not. A required resource record set is missing from the zone.
You encounter 2 when the recursive resolver could not get an authoritative answer — commonly caused by DNSSEC validation failures, unreachable upstream nameservers, or misconfigured zones.
You encounter 8 when a DNS UPDATE prerequisite expected a certain RRset to exist (e.g., an MX record), but the zone does not contain it.
Quando usar qual
For 2 (SERVFAIL): Try a different resolver (e.g., 8.8.8.8 or 1.1.1.1) to isolate the issue. If you control the zone, check DNSSEC signatures, SOA serial consistency, and nameserver reachability. For 8 (NXRRSET): Create the missing RRset in the zone before retrying the update, or change the prerequisite to not require its existence.