DNS 4 NOTIMP vs 9 NOTAUTH
Both DNS 4 (NOTIMP) and 9 (NOTAUTH) 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, 9 means that server Not Authoritative for zone, or Not Authorized. The server is not authoritative for the zone named in the Zone section.
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
Server Not Authoritative for zone, or Not Authorized. The server is not authoritative for the zone named in the Zone section.
When You See It
You sent a dynamic update or zone operation to a server that is not the authoritative master for that zone, or the server rejected it due to TSIG authentication failure.
How to Fix
Send the update to the correct primary authoritative server for the zone. If using TSIG, verify the key name and secret match on both client and server.
Key Differences
DNS 4: Not Implemented. The name server does not support the requested query type or operation.
DNS 9: Server Not Authoritative for zone, or Not Authorized. The server is not authoritative for the zone named in the Zone section.
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 9 when you sent a dynamic update or zone operation to a server that is not the authoritative master for that zone, or the server rejected it due to TSIG authentication failure.
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 9 (NOTAUTH): Send the update to the correct primary authoritative server for the zone. If using TSIG, verify the key name and secret match on both client and server.