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.
Description
No error condition. The query completed successfully and the response contains the requested data.
Quand vous le voyez
This is the normal, successful response to any DNS query — the name was resolved and the answer section contains the requested records.
Comment résoudre
No fix needed. RCODE 0 means the DNS lookup succeeded as expected.
Description
Algorithm not supported. The cryptographic algorithm specified in the TKEY or SIG record is not supported by the server.
Quand vous le voyez
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.
Comment résoudre
Use a mutually supported algorithm. HMAC-SHA256 is widely supported for TSIG; for DNSSEC, check the server's supported algorithm list with its documentation.
Différences clés
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.
Quand utiliser lequel
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.