Chapter 11: Domain Name Service

Overview

This chapter focuses on the Domain Name System (DNS), a service that translates human-readable domain names such as www.mommabears.com to IP addresses such as 10.245.43.5, and vice versa. DNS is a distributed database; each server has its own delegated zone of authority for one or more domains.

The DNS service associated with RHEL is the Berkeley Internet Name Domain (BIND). In this chapter, you'll learn how to edit and modify BIND configuration files to create authoritative DNS servers as well as slave and caching servers.

Once configured, there are a number of BIND utilities that can help find the systems on the local network as well as those on any other connected network, including the Internet.

On the Job 

If you're interested in Dynamic DNS and Linux, one place to start is the Secure Dynamic DNS HOWTO from the Internet Engineering Task Force, at http://ops.ietf.org/dns/dynupd/secure-ddns-howto.html.

Inside the Exam

More Network Services

Both Red Hat exams require that you configure a Linux workstation as a client on a network. On a network with Linux computers, that naturally includes using DNS clients and servers.

This chapter may be related to two different items on the Troubleshooting and System Maintenance portion of the RHCT exam:

• Diagnose and correct misconfigured networking.

• Diagnose and correct host name resolution problems.

It's also related to the following item on the Troubleshooting and System Maintenance portion of the RHCE exam:

• Diagnose and correct problems with network services.

This naturally includes DNS. As noted in the Installation and Configuration requirements associated with the RHCE exam, this means being able to

• Configure DNS as a caching and a slave name service.

The omission of DNS as a master server in the Red Hat Exam Prep requirements is conspicuous by its absence. As always, Red Hat can change its requirements at any time (even halfway through the RHEL 5 release), so check the Red Hat Exam Prep Web site for the latest information (https://www.redhat.com/training/rhce/examprep.html).

But as the only SELinux targeted setting relates to the overwriting of master zone files, there are very few SELinux issues addressed in this chapter.

Nevertheless, this chapter includes basic instructions for configuring a master DNS server.