Linux System Administration

DNS Basics

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about their parts of the tree, and resolvers request domain information from

nameservers on behalf of client programs.

Hierarchical naming schemes like DNS prevent duplication of data. Each domain is

unique, and you can have as many servers as you like within a domain—simply pre-

fix their hostnames to the domain name. A site that controls centralsoft.org, for

example, might have any number of hosts with names like server1.centralsoft.org,

ldap.centralsoft.org, and mail.centralsoft.org.

Advantages of Localized DNS Administration

Smaller organizations often let their ISPs handle DNS administration for them. Set-

ting up your own servers has advantages, though. It gives you total control over

which systems host your public services (e.g., web services and email), and putting

DNS into your infrastructure allows you more scalability: you can add servers as

needed and even do 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’s valuable to control your

own DNS in today’s business environment, instead of having somebody else do it.

Many companies have web-enabled their core business applications. Rather than

replacing working systems, they want to make their legacy applications available

through snazzy new web interfaces. Businesses