DNS 5 REFUSED vs 19 BADMODE
Both DNS 5 (REFUSED) and 19 (BADMODE) belong to the DNS Response Codes (RCODEs) category. 5 indicates that query refused. The name server refuses to perform the requested operation for policy reasons. Meanwhile, 19 means that bad TKEY Mode. The TKEY mode field contains a value not supported by the server.
Description
Query refused. The name server refuses to perform the requested operation for policy reasons.
When You See It
The server rejected your query due to access control — for example, a recursive resolver that only serves its own network, or a zone transfer blocked by ACL.
How to Fix
Check the server's allow-query, allow-recursion, or allow-transfer ACLs. If you are not authorized to use this resolver, switch to a public DNS service.
Description
Bad TKEY Mode. The TKEY mode field contains a value not supported by the server.
When You See It
Your client attempted a TKEY key exchange using a mode (e.g., Diffie-Hellman, GSS-API) that the server does not support or has not been configured for.
How to Fix
Check which TKEY modes the server supports and configure your client to use a compatible mode. GSS-TSIG (mode 3) is the most widely deployed.
Key Differences
DNS 5: Query refused. The name server refuses to perform the requested operation for policy reasons.
DNS 19: Bad TKEY Mode. The TKEY mode field contains a value not supported by the server.
You encounter 5 when the server rejected your query due to access control — for example, a recursive resolver that only serves its own network, or a zone transfer blocked by ACL.
You encounter 19 when your client attempted a TKEY key exchange using a mode (e.g., Diffie-Hellman, GSS-API) that the server does not support or has not been configured for.
When to Use Which
For 5 (REFUSED): Check the server's allow-query, allow-recursion, or allow-transfer ACLs. If you are not authorized to use this resolver, switch to a public DNS service. For 19 (BADMODE): Check which TKEY modes the server supports and configure your client to use a compatible mode. GSS-TSIG (mode 3) is the most widely deployed.