Linux System Administration

Configuring an Authoritative DNS Server

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Basically, resolv.conf controls the queries that browsers and other clients make for

domain names, while named answers the queries and makes sure information is kept

up-to-date on all servers.

Answering Queries

Figure 3-2 depicts the process used to answer a query. Let’s break it down.

In the upper-left corner of the figure is a drawing of a server tower (in our example

this server is called server1.centralsoft.org; it performs the same function as ns1.

google.com). Assume the server is running Linux and BIND. A server at a higher level

directs resolvers to the system (in the case of server1.centralsoft.org, a TLD

nameserver for the .org domain sends the requests).

The named daemon listens on UDP port 53 for anyone making requests for names in

the domain. When named receives a request, it consults its configuration file, /etc/

named.conf. If the server has information on the domain in question, it looks in the

appropriate zone file. If the zone file has the information requested, the server hands

it off to the system querying for the information.

Some people refer to configuration files as rule files. This makes some sense because

correct DNS operation requires tight compliance with its rules and protocols. How-

ever, the zone files actually function as part of the DNS directory. Their primary

function is to provide information, not to enforce rules.

Primar ...