RCode is a Word property that represents the result code returned by a DNS server as part of a response to a DNS query. RCode may contain one of the following values and meanings:
- 0 - No error condition.
- 1 - Query Format error. The name server was unable to interpret the query.
- 2 - Server failure. The name server was unable to process this query due to a problem with the name server.
- 3 - Name Error. Meaningful only for responses from an authoritative name server, this code signifies that the domain name referenced in the query does not exist.
- 4 - Not Implemented. The name server does not support the requested kind of query.
- 5 - Operation Refused. The name server refuses to perform the specified operation for policy reasons. For example, a name server may not wish to provide the information to the particular requester, or a name server may not wish to perform a particular operation (e.g., zone transfer) for particular data.
- 6 - Reserved for future use.
- 7 - Reserved for future use.
- 8 - Reserved for future use.
- 9 - Reserved for future use.
- 10 - Reserved for future use.
- 11 - Reserved for future use.
- 12 - Reserved for future use.
- 13 - Reserved for future use.
- 14 - Reserved for future use.
- 15 - Reserved for future use.
RCode is represented in a DNS header as a 4-bit field. Changing the value of RCode insures that the appropriate bit field is updated in the DNS header for the message packet.