DNS 1 FORMERR vs 9 NOTAUTH
Both DNS 1 (FORMERR) and 9 (NOTAUTH) belong to the DNS Response Codes (RCODEs) category. 1 indicates that format error. The name server was unable to interpret the query due to a malformed DNS message. 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
Format error. The name server was unable to interpret the query due to a malformed DNS message.
When You See It
Your DNS client or library sent a query the server could not parse, often caused by a buggy resolver, corrupted packet, or unsupported EDNS options.
How to Fix
Check your DNS client or library version for known bugs. Capture the raw query with dig or Wireshark and verify it conforms to the DNS wire format.
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 1: Format error. The name server was unable to interpret the query due to a malformed DNS message.
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 1 when your DNS client or library sent a query the server could not parse, often caused by a buggy resolver, corrupted packet, or unsupported EDNS options.
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 1 (FORMERR): Check your DNS client or library version for known bugs. Capture the raw query with dig or Wireshark and verify it conforms to the DNS wire format. 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.