DNS 0 NOERROR vs 21 BADALG
Both DNS 0 (NOERROR) and 21 (BADALG) belong to the DNS Response Codes (RCODEs) category. 0 indicates that no error condition. The query completed successfully and the response contains the requested data. Meanwhile, 21 means that algorithm not supported. The cryptographic algorithm specified in the TKEY or SIG record is not supported by the server.
Descripción
No error condition. The query completed successfully and the response contains the requested data.
Cuándo lo verás
This is the normal, successful response to any DNS query — the name was resolved and the answer section contains the requested records.
Cómo solucionarlo
No fix needed. RCODE 0 means the DNS lookup succeeded as expected.
Descripción
Algorithm not supported. The cryptographic algorithm specified in the TKEY or SIG record is not supported by the server.
Cuándo lo verás
Your TKEY negotiation or DNSSEC operation requested an algorithm (e.g., HMAC-SHA512) that the server has not been compiled with or configured to accept.
Cómo solucionarlo
Use a mutually supported algorithm. HMAC-SHA256 is widely supported for TSIG; for DNSSEC, check the server's supported algorithm list with its documentation.
Diferencias clave
DNS 0: No error condition. The query completed successfully and the response contains the requested data.
DNS 21: Algorithm not supported. The cryptographic algorithm specified in the TKEY or SIG record is not supported by the server.
You encounter 0 when this is the normal, successful response to any DNS query — the name was resolved and the answer section contains the requested records.
You encounter 21 when your TKEY negotiation or DNSSEC operation requested an algorithm (e.g., HMAC-SHA512) that the server has not been compiled with or configured to accept.
Cuándo usar cada uno
For 0 (NOERROR): No fix needed. RCODE 0 means the DNS lookup succeeded as expected. For 21 (BADALG): Use a mutually supported algorithm. HMAC-SHA256 is widely supported for TSIG; for DNSSEC, check the server's supported algorithm list with its documentation.