DNS_HEADER structure (windns.h)
The DNS_HEADER structure contains DNS header information used when sending DNS messages as specified in section 4.1.1 of RFC 1035.
Syntax
typedef struct _DNS_HEADER {
WORD Xid;
WORD Flags;
BYTE RecursionDesired : 1;
BYTE Truncation : 1;
BYTE Authoritative : 1;
BYTE Opcode : 4;
BYTE IsResponse : 1;
BYTE ResponseCode : 4;
BYTE CheckingDisabled : 1;
BYTE AuthenticatedData : 1;
BYTE Reserved : 1;
BYTE RecursionAvailable : 1;
WORD QuestionCount;
WORD AnswerCount;
WORD NameServerCount;
WORD AdditionalCount;
} DNS_HEADER, *PDNS_HEADER;
Members
Xid
A value that specifies the unique DNS message identifier.
Flags
RecursionDesired
A value that specifies whether recursive name query should be used by the DNS name server.
Value | Meaning |
---|---|
|
Do not use recursive name query. |
|
Use recursive name query. |
Truncation
A value that specifies whether the DNS message has been truncated.
Value | Meaning |
---|---|
|
The message is not truncated. |
|
The message is truncated. |
Authoritative
A value that specifies whether the DNS server from which the DNS message is being sent is authoritative for the domain name's zone.
Value | Meaning |
---|---|
|
The DNS server is not authoritative in the zone. |
|
The DNS server is authoritative in the zone. |
Opcode
A value that specifies the operation code to be taken on the DNS message as defined in section 4.1.1 of RFC 1035 as the OPCODE field.
IsResponse
A value that specifies whether the DNS message is a query or a response message.
Value | Meaning |
---|---|
|
The DNS message is a query. |
|
The DNS message is a response. |
ResponseCode
The DNS Response Code of the message.
CheckingDisabled
Windows 7 or later: A value that specifies whether checking is supported by the DNS resolver.
Value | Meaning |
---|---|
|
Checking is enabled on the DNS resolver. |
|
Checking is disabled on the DNS resolver. |
AuthenticatedData
Windows 7 or later: A value that specifies whether the DNS data following the DNS_HEADER is authenticated by the DNS server.
Value | Meaning |
---|---|
|
The DNS data is not authenticated. |
|
The DNS data is authenticated. |
Reserved
Reserved. Do not use.
RecursionAvailable
A value that specifies whether recursive name query is supported by the DNS name server.
Value | Meaning |
---|---|
|
Recursive name query is not supported. |
|
Recursive name query is supported. |
QuestionCount
The number of queries contained in the question section of the DNS message.
AnswerCount
The number of resource records (RRs) contained in the answer section of the DNS message.
NameServerCount
The number of DNS name server RRs contained in the authority section of the DNS message. This value is the number of DNS name servers the message has traversed in its search for resolution.
AdditionalCount
Reserved. Do not use.
Requirements
Requirement | Value |
---|---|
Minimum supported client | Windows 2000 Professional [desktop apps only] |
Minimum supported server | Windows 2000 Server [desktop apps only] |
Header | windns.h |