DNS 2 SERVFAIL vs 4 NOTIMP
Both DNS 2 (SERVFAIL) and 4 (NOTIMP) 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, 4 means that not Implemented. The name server does not support the requested query type or operation.
Descripción
Server failure. The name server encountered an internal error while processing the query.
Cuándo lo verás
The recursive resolver could not get an authoritative answer — commonly caused by DNSSEC validation failures, unreachable upstream nameservers, or misconfigured zones.
Cómo solucionarlo
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.
Descripción
Not Implemented. The name server does not support the requested query type or operation.
Cuándo lo verás
You sent a query type (e.g., IXFR, dynamic update) that the server does not support or has disabled.
Cómo solucionarlo
Verify the server supports the query type you are using. If you need zone transfers or dynamic updates, enable them in the server configuration.
Diferencias clave
DNS 2: Server failure. The name server encountered an internal error while processing the query.
DNS 4: Not Implemented. The name server does not support the requested query type or operation.
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 4 when you sent a query type (e.g., IXFR, dynamic update) that the server does not support or has disabled.
Cuándo usar cada uno
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 4 (NOTIMP): Verify the server supports the query type you are using. If you need zone transfers or dynamic updates, enable them in the server configuration.