Query / Response

Response Code

0

Query

0

No error

1

Response

1

Format error

2

Server failure

Opcode

3

Non-existent domain (NXDOMAIN)

0

Standard Query (QUERY)

4

Query type not implemented

1

Inverse Query (IQUERY)

5

Query refused

2

Server Status Request (STATUS)

QDCOUNT

No. of entries in the Question Section

AA

1 = Authoritative Answer

ANCOUNT

No. of resource records in Answer Section

TC

1 = TrunCation

NSCOUNT

No. of name server resource records in Authority Section

RD

1 = Recursion Desired

ARCOUNT

No. of resource records in Additional Information Section.

RA

1 = Recursion Available

Z

Reserved; set to 0 (The DNS Evil bit)