DNS Message Resource Record Field Formats
(Page 1 of 5)
The exchange of information in DNS consists of a series of client/server transactions. Clients send requests, or queries, to servers, and the servers send back responses. DNS servers are of course database servers, and store DNS name database information in the form of resource records (RRs). The questions asked by clients are requests for information from a DNS's servers database, and they are answered by the DNS server looking up the requested resource records and putting them into the DNS response message.
The Answer, Authority and Additional sections of the overall DNS message format are the places where servers put DNS resource records to be sent back to a client. Each section consists of zero or more records, and in theory, any record can be placed in any section. The sections only differ in the semantics (meaning) that the client draws from a record being in one section compared to the other. The topic on DNS general messaging contains more on these three sections and how they are used.
Resource records have two representations: binary and text. The text format is used for master files edited by humans, and is the subject of a topic later in this section. The binary representation consists of regular numeric and text fields just like the other fields in the DNS message format.
Home - Table Of Contents - Contact Us
The TCP/IP Guide (http://www.TCPIPGuide.com)
Version 3.0 - Version Date: September 20, 2005
© Copyright 2001-2005 Charles M. Kozierok. All Rights Reserved.
Not responsible for any loss resulting from the use of this site.