Data from a name server is stored and distributed in a format known
as a resource record. Each response from a name server can contain
several resource records, which can contain a variety of information.
The format of a response is defined in RFC 1035. It includes the following
sections:
- A question section, echoing the query for which the response is
returned.
- An answer section, containing resource records matching the query.
- An additional section, containing resource records that do not
match the query, but might provide useful information for the client.
For example, the response to a query for the host name of a name server
for a specific zone includes the IP address of that name server in
the additional section.
- An authority section, containing information specific to the type
of response made to the query. If a referral is returned, this section
contains the domain names of name servers that could provide an authoritative
answer. If a negative response is returned indicating the name does
not exist, this section contains a Start Of Authority (SOA) record
defining the zone of authority of the responding name server.