DNS 2 SERVFAIL vs 6 YXDOMAIN
Both DNS 2 (SERVFAIL) and 6 (YXDOMAIN) 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, 6 means that name Exists when it should not. Used in dynamic updates to indicate a name that should not exist already has records.
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
Name Exists when it should not. Used in dynamic updates to indicate a name that should not exist already has records.
Quando você o vê
A DNS UPDATE prerequisite check failed because the domain name already exists when the update expected it to be absent.
Como corrigir
Review your dynamic update prerequisites. If you expect to create a new name, remove the existing records first or change the prerequisite to allow existing names.
Diferenças principais
DNS 2: Server failure. The name server encountered an internal error while processing the query.
DNS 6: Name Exists when it should not. Used in dynamic updates to indicate a name that should not exist already has records.
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 6 when a DNS UPDATE prerequisite check failed because the domain name already exists when the update expected it to be absent.
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 6 (YXDOMAIN): Review your dynamic update prerequisites. If you expect to create a new name, remove the existing records first or change the prerequisite to allow existing names.