wiki:dns_primer

Version 1 (modified by Jamie McClelland, 13 years ago) (diff)

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What is a domain name server? What is a registrar?

Understanding domain name servers and registrars is often confusing. Below is a brief overview of what it all means

All Internet computers on the Internet as assigned a number, similar to a phone number. For example, the server that runs the web site for Paper Tiger TV has the address 209.51.172.6. Since that number is difficult to remember, we have assigned the domain name papertiger.org to it. When you want to visit the web site, your web browser looks up the domain name papertiger.org, retrieves the actual number from a server on the Internet, and then delivers you to the web site. In much the same way, you might not remember a phone number but you do remember the name "Paper Tiger TV" so you might call information and ask for the number for Paper Tiger TV in order to call them.

Like phone numbers, the thing with domain names is that they must be unique. You can't have two papertiger.org addresses - it would be like having two telephone numbers that were identical.

To help ensure that all domain names are unique, The Internet Corporation for Assigned Names and Numbers (ICANN), a nonprofit organization, was formed to over see the whole thing. Since it is so huge, they have in turn delegated responsibility. For example, the management of all domain names that end in .org have been delegated to a nonprofit organization called Public Interest Registry (www.pir.org). PIR is responsible for maintaining a huge database of all the domains that end with .org. Domains ending in .com are handled by yet another organization.

So can I get a domain name by contacting Public Interest Registry?

Well, not exactly. Public Interest Registry focuses on managing the technical aspects of the domains that end in .org, not selling new domains to people like us.

If you want to get your own domain name, you need to go through a "registrar." Registrars are, typically, for profit companies, that have been officially accredted by ICANN to sell domain names. There are dozens of registrars, such as Dotster or GoDaddy or TuCows. So, when you purchase a domain name, such as papertiger.org, you would pay a company like Dotster about $15/year. Dotster, in turn, would tell the folks at PIR to add this domain to their database with a record saying they are the registrar.

So far so good.

The registrar also keeps at least one more piece of important information: the address of the computer that can tell you what numerical Internet address the domain papertiger.org points to. This computer is known as the domain name server (DNS), it's like the 411 operator. Note: the registrar does NOT necessarily tell you what numerical address papertiger.org points to. Instead, it tells you the address of the computer that you should ask. It's like when you call the cable company and you always have to be transferred to someone else because the person that picked up the phone can't answer your question.

When you want to move your web site from one Internet Service Provider to another Internet Internet Service Provider - it is this crucial piece of information that must be changed: the address of the Domain Name Server. Usually it will be set to a server run by your Internet Service Provider. So if you don't change this address, then people who go to your domain name will continue to go to the old Internet Service Provider.

Finally, a little review:

When your web browser asks for the web site papertiger.org the following (an appoximation) happens:

  • The domain name ends in .org, therefore the PIR central database is asked if it knows anything about papertiger.org
  • PIR looks up the domain name and says - yes, we have a record. According to our database, papertiger.org was registered with Dostser. You should contact dotster to get more information.
  • Dotster is then asked: what do you know about papertiger.org?
  • Dotster looks up the record, and sees that there are two domain name server computers assigned to papertiger.org: a.ns.mayfirst.org and b.ns.mayfirst.org (two computers are typically assigned in the event that one is down).
  • Next, a.ns.mayfirst.org is contacted and asked: what is the numerical address for papertiger.org? It responds: 209.51.172.6 and the process is over.