Resource Records

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.