DNS 4 NOTIMP vs 21 BADALG
Both DNS 4 (NOTIMP) and 21 (BADALG) belong to the DNS Response Codes (RCODEs) category. 4 indicates that not Implemented. The name server does not support the requested query type or operation. Meanwhile, 21 means that algorithm not supported. The cryptographic algorithm specified in the TKEY or SIG record is not supported by the server.
Descrição
Not Implemented. The name server does not support the requested query type or operation.
Quando você o vê
You sent a query type (e.g., IXFR, dynamic update) that the server does not support or has disabled.
Como corrigir
Verify the server supports the query type you are using. If you need zone transfers or dynamic updates, enable them in the server configuration.
Descrição
Algorithm not supported. The cryptographic algorithm specified in the TKEY or SIG record is not supported by the server.
Quando você o vê
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.
Como corrigir
Use a mutually supported algorithm. HMAC-SHA256 is widely supported for TSIG; for DNSSEC, check the server's supported algorithm list with its documentation.
Diferenças principais
DNS 4: Not Implemented. The name server does not support the requested query type or operation.
DNS 21: Algorithm not supported. The cryptographic algorithm specified in the TKEY or SIG record is not supported by the server.
You encounter 4 when you sent a query type (e.g., IXFR, dynamic update) that the server does not support or has disabled.
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.
Quando usar qual
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. 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.