DNS 1 FORMERR vs 5 REFUSED
Both DNS 1 (FORMERR) and 5 (REFUSED) 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, 5 means that query refused. The name server refuses to perform the requested operation for policy reasons.
描述
Format error. The name server was unable to interpret the query due to a malformed DNS message.
何时出现
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.
如何修复
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.
描述
Query refused. The name server refuses to perform the requested operation for policy reasons.
何时出现
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.
如何修复
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.
主要区别
DNS 1: Format error. The name server was unable to interpret the query due to a malformed DNS message.
DNS 5: Query refused. The name server refuses to perform the requested operation for policy reasons.
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 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.
何时使用哪个
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 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.