DNS 4 NOTIMP vs 17 BADKEY
Both DNS 4 (NOTIMP) and 17 (BADKEY) 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, 17 means that key not recognized. The TSIG key name in the message is not configured on the server.
Description
Not Implemented. The name server does not support the requested query type or operation.
When You See It
You sent a query type (e.g., IXFR, dynamic update) that the server does not support or has disabled.
How to Fix
Verify the server supports the query type you are using. If you need zone transfers or dynamic updates, enable them in the server configuration.
Description
Key not recognized. The TSIG key name in the message is not configured on the server.
When You See It
Your TSIG-signed query or update references a key name that the server does not have in its keyring, so it cannot verify the signature.
How to Fix
Ensure the TSIG key name matches exactly (case-sensitive) on both client and server. Add the missing key to the server's configuration if it is a new key.
Key Differences
DNS 4: Not Implemented. The name server does not support the requested query type or operation.
DNS 17: Key not recognized. The TSIG key name in the message is not configured on 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 17 when your TSIG-signed query or update references a key name that the server does not have in its keyring, so it cannot verify the signature.
When to Use Which
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 17 (BADKEY): Ensure the TSIG key name matches exactly (case-sensitive) on both client and server. Add the missing key to the server's configuration if it is a new key.