LPI Linux Certification in a Nutshell, 2nd Edition

Objective 5: Set Up and Configure Basic DNS Services

The DNS is the distributed database of name-to-IP-address translations. Technically, it isn't necessary to use host and domain names such as www.lpi.org, because it's the actual IP address that the computer requires to establish communications. DNS was created to allow the use of more convenient global domain names instead. For example, when a user enters a DNS name as part of a URL in a browser, the name portion is sent to a DNS server to be resolved into an IP address. Once the address is found, it is used to rewrite the URL and directly fetch the web page.

On the Exam

You must be familiar with the concept of name resolution on the Internet using DNS.

The server daemon that implements DNS is named, the name daemon, which is part of the Berkeley Internet Name Daemon package (BIND). It is named's job to respond to requests from the resolver and return an IP address.

The Resolver

The code that resolves names to IP addresses using DNS for client programs is implemented in system libraries collectively called the resolver. The resolver uses one of several means to determine an IP address from a hostname or domain name:

Static local files

The local file /etc/hosts can contain name-to-address mapping for a few systems on a network. However, for large enterprises, using static local files to manage IP address resolution is problematic due to the frequent changes required in the data. Updating all of the client systems would be impractical. ...