DNS 6 YXDOMAIN vs 21 BADALG
Both DNS 6 (YXDOMAIN) and 21 (BADALG) belong to the DNS Response Codes (RCODEs) category. 6 indicates that name Exists when it should not. Used in dynamic updates to indicate a name that should not exist already has records. Meanwhile, 21 means that algorithm not supported. The cryptographic algorithm specified in the TKEY or SIG record is not supported by the server.
説明
Name Exists when it should not. Used in dynamic updates to indicate a name that should not exist already has records.
このコードが表示される場合
A DNS UPDATE prerequisite check failed because the domain name already exists when the update expected it to be absent.
解決方法
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.
説明
Algorithm not supported. The cryptographic algorithm specified in the TKEY or SIG record is not supported by the server.
このコードが表示される場合
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.
解決方法
Use a mutually supported algorithm. HMAC-SHA256 is widely supported for TSIG; for DNSSEC, check the server's supported algorithm list with its documentation.
主な違い
DNS 6: Name Exists when it should not. Used in dynamic updates to indicate a name that should not exist already has records.
DNS 21: Algorithm not supported. The cryptographic algorithm specified in the TKEY or SIG record is not supported by the server.
You encounter 6 when a DNS UPDATE prerequisite check failed because the domain name already exists when the update expected it to be absent.
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.
どちらをいつ使うか
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. 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.