Bind 9 Administrator Reference Manual

Chapter 1. Introduction
literal user input Fixed Width Bold
program output Fixed Width
The following conventions are used in descriptions of the BIND configuration file:
To describe: We use the style:
keywords Fixed Width
variables Fixed Width
Optional input [Text is enclosed in square brackets]
1.4. The Domain Name System (DNS)
The purpose of this document is to explain the installation and upkeep of the BIND software package,
and we begin by reviewing the fundamentals of the Domain Name System (DNS) as they relate to BIND.
1.4.1. DNS Fundamentals
The Domain Name System (DNS) is the hierarchical, distributed database. It stores information for
mapping Internet host names to IP addresses and vice versa, mail routing information, and other data
used by Internet applications.
Clients look up information in the DNS by calling a resolver library, which sends queries to one or more
name servers and interprets the responses. The BIND 9 software distribution contains both a name server
and a resolver library.
1.4.2. Domains and Domain Names
The data stored in the DNS is identified by domain names that are organized as a tree according to
organizational or administrative boundaries. Each node of the tree, called a domain, is given a label. The
domain name of the node is the concatenation of all the labels on the path from the node to the root node.
This is represented in written form as a string of labels listed from right to left and separated by dots. A
label need only be unique within its parent domain.
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