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DNS: A Simple Explanation

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DNS means Domain Name System - the protocol that provides the framework for web browsing.

DNS, whenever I hear it I think of another common acronym -- DNA. While the words that make up the acronym DNS are much easier to spell than those represented by DNA, both concepts may seem similarly complex. If you feel this way, read on for a simple explanation of how domain names work, what an IP address is, and how DNS works.

DNS stands for Domain Name System, a system of computers that provides the infrastructure allowing browsing of the World Wide Web. In its most simple definition, the Domain Name System is a conglomeration of root servers that houses the Internet Protocol (IP) addresses of the DNS name servers that have authority over individual domains of every registered Internet domain name.

Many people do not know that internet servers can only be addressed by a numeric address (IP address). The key role that DNS name servers play is in translating domain names into IP addresses.

So, when you purchase a domain name from a name registrar, such as Network Solutions, the registar will associate with that domain name a minimum of two DNS name servers. These DNS name servers are configured and maintained by the company that hosts your web site for you--not by the name registrar. However, the name registrar does send the DNS name server information that you provide at the time of purchase to InterNIC for storage in the root servers that make up the Domain Name System.

The role of the DNS name servers maintained by your hosting company is to respond to a query for a specific domain name with the precise location on the exact web hosting server (using that server’s IP address) where that domain name, and thus web site, is located.

The role of the root servers that make up the Domain Name System of the World Wide Web is to send an ISP’s equipment, and thus the web browser, to the correct DNS name server that will in turn point to the web site being requested.

With this system, web site users only need to know your domain name to find your web site, it does not matter to them what the IP address is for the individual server on which your site is housed. If you, for example, upgrade your site to a DASH dedicated server solution, we update DNS to point to the IP address of your new server. Your visitors still visit your site by using only your domain name; even though your IP address changed it is transparent to them. In the dot-com world, this kind of flexibility is crucial.

Here is what happens:

  1. I log onto my Internet Service Provider (ISP) to use the Web.
  2. I open my web browsing software (i.e. Internet Explorer or Netscape Navigator) and type http://www.dashsystems.com into the location bar.
  3. My computer asks my ISP's DNS server(s) for the IP address of www.dashsystems.com.
  4. My ISP’s equipment first checks its memory cache to find out if it has fulfilled a request for this same address recently.
  5. If it has not, my ISP’s equipment will communicate with InterNIC’s conglomeration of root servers that make up the Domain Name System to find out which DNS server holds the IP address of the domain name.
  6. My ISP’s equipment takes the address provided and sends a query to the authoritative DNS server for that domain.
  7. The authoritative DNS server responds with the IP address of the desired server.
  8. My ISP's equipment updates its memory cache with the address so that it respond to future requests without all the steps above.
  9. My ISP's equipment responds to my computer with the IP address of the server for which I am looking.
  10. My computer updates its memory cache so that it doesn't have to look up the address for a while.
  11. My computer hands the address to my browser, which opens a connection to the server (using the specified IP address) and retrieves the first page from the site I requested.
  12. My browser displays the requested page on my screen.

If you have other questions about how the web works, feel free to contact DASH Systems. Stay tuned to this section of our web site for other useful information.