Understanding the Domain Name System

Conclusion

The domain name system was created to assist human users with finding specific computers. Computers identify each other by IP address (ex. 216.97.58.58). Since most humans would not remember that to look at for this article, I bought the domain name hunterthinks.com.

Changing words into numbers

When a user types a domain name into a browser, email client, ftp client, or some other appropriate place, the client queries a Domain Name Service (DNS) server for the IP address of the computer associated with the domain name.

Diagram of a DNS request

For example, when you type hunterthinks.com into your browser, the browser does not go straight to my web server. It first asks the DNS server what the IP address for hunterthinks.com is. In this case, it is 216.97.58.58. Then, the browser asks for data from 216.97.58.58, not hunterthinks.com.

Hierarchy

The original intent of the domain name system was to arrange domains into a hierarchy. The top level of the hierarchy included com, edu, mil, gov, org, and net. Then, within each of these top-level or first level domains, all other domains would reside. Now, we have cc, us, de, jp, and many others that represent countries or territories worldwide. (On June 26, 2001, biz and info came into use also.)

Using www.hunterthinks.com as an example, com is the first level, hunterthinks is the second level domain, and www is the subdomain or third level domain.

Third-level domains

AddressIP
dell.com143.166.82.178
www.dell.com143.166.224.86
ftp1.dell.com143.166.82.8

Most people take the www for granted when using the Internet. However, there are times when it is necessary to use third-level domains. Start by typing dell.com into your browser. You are automatically taken to Dell’s website. Now go to www.dell.com. Also, Dell’s website. Now type ftp1.dell.com into your browser. This is Dell’s FTP site. Changing the third level domain in the address changed where your data request was directed.

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