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Configuring DNS   «Prev  Next»
Lesson 8 Complete the DNS configuration
Objective Configure the DNS clients and troubleshooting the DNS configuration.

Complete the DNS Configuration

To configure a UNIX DNS client, you need only to alter the /etc/resolv.conf file for each host that you want to participate in the domain. Make sure that you backup this file before you edit it. You may also want to check the /etc/hosts file to make sure that it contains only the loopback entry, as well as one for that particular machine. Before editing this file, it is a good idea to back up any original file in case of a problem.

Troubleshooting DNS problems

Use ping to test or troubleshoot your configuration. Then, telnet to any system in your domain using the fully qualified domain name (FQDN). If you encounter serious problems, you can back out of the DNS installation by:
  1. Changing the /etc/resolv.conf file back to its original (remember: always back up any file you edit)
  2. Restoring your /etc/hosts file to its original form
  3. Killing your name server process

Advantages of Localized DNS Administration

Smaller organizations often let their ISPs handle DNS administration for them. Setting up your own servers has advantages.
It gives you total control over which systems host your public services (i.e., web services and email), and putting DNS into your infrastructure allows you more scalability:
  1. you can add servers as needed and
  2. perform load balancing among them.
This becomes important if you own and operate several active domains or internal authentication services. You also have more control over keeping your names updated. In short, it adds value when you control your own DNS in today's business environment, i nstead of outsourcing this task to another company. Many companies have web-enabled their core business applications. Rather than replacing working systems, they want to make their legacy applications available using web interfaces.
Businesses do this by adding web frontends while using web-based backends to connect disparate systems together.
The IT departments of large companies such as General Motors use application servers such as JBoss, IBM's Web- Sphere, and Apache Tomcat for the backends and HTML, CSS AND JavaScript for the frontends. In every case, DNS becomes an integral part of web-enabling because such systems use directory servers that communicate with one another. DNS also holds a prominent place in the emergence of web services and an executable Internet, where people can use applications such as those offered by Google and AWS.
Resolving IP addresses quickly and dependably is critical to the success of these products outside on the Internet and inside enterprises. Consider DNS configuration and management one of the most valuable system administration skill sets you can have.