4.1. Format

All communications inside of the domain protocol are carried in a single format called a message. The top level format of message is divided into 5 sections (some of which are empty in certain cases) shown below:

The header section is always present. The header includes fields that specify which of the remaining sections are present, and also specify whether the message is a query or a response, a standard query or some other opcode, etc.

The names of the sections after the header are derived from their use in standard queries. The question section contains fields that describe a question to a name server. These fields are a query type (QTYPE), a query class (QCLASS), and a query domain name (QNAME). The last three sections have the same format: a possibly empty list of concatenated resource records (RRs). The answer section contains RRs that answer the question; the authority section contains RRs that point toward an authoritative name server; the additional records section contains RRs which relate to the query, but are not strictly answers for the question.

• 4.1.1. Header section format
• 4.1.2. Question section format
• 4.1.3. Resource record format
• 4.1.4. Message compression

Dies ist ein Mirror von Connected: An Internet Encyclopedia von Brent Baccala. Die offizielle Projekt-Homepage findet sich im Web unter www.freesoft.org/CIE. Dieser Mirror wurde zuletzt aktualisiert am Samstag, 28 Januar 2006 18:17 +0100.