DNS: Difference between revisions
→DNS Headers
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== Fields ==
*ID: 2 Bytes Identifier:
A 16-bit identification field generated by the device that creates the DNS query.
It is copied by the server into the response, so it can be used by that device to match that query to the corresponding reply received from a DNS server.
This is used in a manner similar to how the Identifier field is used in many of the ICMP message types.
*QR: 1/8 (1 bit) Query/Response Flag:
Differentiates between queries and responses.
Set to 0 when the query is generated; changed to 1 when that query is changed to a response by a replying server.
*Opcode: 1/2 (4 bits)
Specifies the type of query
Set by creator of the message
Copied unchanged into Response
0 Query
1 IQuery
2 Status
3 (Reserved)
4 Notify
5 Update
*AA:
*TC:
*RD:
*RA:
*Z:
*RCode:
*QDCount:
*ANCount:
*NSCount:
*ARCount:
== Flags ==
* Recursion Desired Field
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