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I guess the greater question should be Why is a domain registrar necessary, but does one for ease of the average man. I understand that the purpose of a registrar is so that way all people have to do is type into their browsers http://www.example.com/most_trafficked_domain_ever and they are taken to your physical server location, regardless of if you move.

That being said, is it not possible for them to connect directly to your domain without a registrar?

*I assume it is, that is how "some parts" of the internet work.

  • Well, I suppose you could just give out your IP Address. You would just be limited to one website per server without virtual hosting. – StephenCollins Oct 26 '17 at 17:01
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You can run a website on an IP address like http://192.0.2.4/. Doing so does not require a domain name. However, IP addresses are typically tied to a specific hosting company or internet service provider. If you want to move your website to a new host or ISP, your IP address will change.

Obtaining a domain name allows you to map that domain name to the current IP address of your website and to update that IP address when you change hosting. To get a domain name, you need to register one at a domain registrar. There is no way to get a domain name without going through a registrar.

Domain names have to be unique such that no to websites have the same name. This requires a central way of requesting names, registering names, and mapping names to numerical addresses. This system is the DNS system and is overseen by the "Internet Corporation for Assigned Names and Numbers" (ICANN). ICANN was created to fulfill this role by the US government in cooperation with the organizations that created the internet.

ICANN oversees a set of DNS servers known as the "root" servers. These servers are for the top level domains (TLDs) like .com, .net, and .org. They specify the IP addresses of the DNS servers for all the TLDs. ICANN also controls the number of top level domains and awards contracts to operate them.

Each top level domain is where registrations actually happen for individual websites. Each top level domain has its own policies for who can register a domain, with what domain registrars, and how much those domain names will cost.

Registrars are responsible for inserting records for each domain into the into the TLD servers. Those records specify the name servers used for the individual domain. So for example, to get the IP address of example.com, all the following have to happen (although DNS caches everything so all queries don't happen every time):

  • Query NS records from the root name servers for .com
  • Query NS records from .com's name servers for example.com
  • Query example.com's name servers for the IP address of example.com

It is also possible to run a website on a "third level domain" such as my-sub-domain.example.com. Because anybody who runs a domain can in turn dole out domains underneath it, such subdomains are widely available. They can often be registered for free and with little hassle. They are often doled out in conjunction with dynamic DNS services.

There are some big disadvantages to running a website using a third level domain:

  • Your rights to the name are not usually well protected compared to getting a second level domain. The name could be revoked for many reasons at the whim of the domain owner, or because the domain owner doesn't want to provide the service anymore.
  • Browsers allow cookies to be set at the second level domain meaning that cookies can be shared between many sites which cat compromise security.
  • Search engines take a dim view of third level domain sites. They find lots of spam on them and often penalize an entire domain with many unrelated websites under it. Search engines often give a bonus to a second level domain because paying $10 is a small sign of commitment and quality.

See also:

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    ICANN does not run root servers (except one), root servers operators do. Some TLD namespaces are from the start third level or more, like .co.uk (registrations directly under .uk is something new), .co.za, or .us in the past. And there is no disadvantage on using them. – Patrick Mevzek Oct 29 '17 at 0:16
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OK, let's talk through how your web browser turns www.example.com into an IP address, assuming that it doesn't already have anything cached, which it undoubtedly will if you've ever done any DNS lookups before. Technically, it's your operating system doing this, not the browser -- the browser just asks the operating system and gets the response. And in fact you almost certainly have a caching DNS server somewhere downstream of you, so your computer will never actually need to do this itself, even the first time you use it.

First, it checks to see if already knows about www.example.com. Nope. How about example.com? Still no. How about just com? Still no. Now it would be stuck, except that your computer contains a hard-coded list of the IP addresses of the root DNS servers, which change only very infrequently. So it asks a root server to tell it about com, and the root server tells it what DNS servers are authoritative for com. Then it asks an authoritative server for com about example.com, and the com server tells it what DNS servers are authoritative for example.com. Then it asks an authoritative server for example.com for an A record for www.example.com, and gets the answer it needed.

The role of the domain registrar is to get your DNS servers listed on the authoritative server for com, as the authoritative servers for example.com, so that people's computers can find them. That's why you need a registrar.

  • I think I understand. – Matthew T. Scarbrough Oct 26 '17 at 17:55
  • What you say is not what was done traditionnally, it is only recently that QNAME minimization make it possible to do stuff like you say, otherwise the true case and the most frequent one still today is that the full name is used at each stage. So it starts by querying root servers with www.example.com, etc... – Patrick Mevzek Oct 29 '17 at 0:18
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The previous replies basically told you already why, except two points:

  • the job of a registrar and a DNS operator and a webhosting company are technically separate and could be offered by different entities (ex: you could have registered your domain at GoDaddy, using CloudFlare for the DNS, and hosting the website on Amazon cloud), even if very often you will find a registrar doing all three
  • having to use a registrar or not depend on the registries: most registries mandate the use of a registrar or are forced to go through registrars (like ICANN mandated in the past for gTLDs), but some registries in ccTLDs allow to register domain directly with them, in parallel of using registrars (.DE is an example) or some very small ccTLDs starting up do not even have registrars and everything is centrally done by the registry
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"I understand that the purpose of a registrar is so that way all people have to do is type into their browsers http://www.example.com/most_trafficked_domain_ever and they are taken to your physical server location, regardless of if you move. "

That is only part of what a Registrar might do. Getting a domain name purchased and then online requires quite a bit of technical know how, beyond even what most tech-savy consumers know. So I'd say, sure, it could be possible, but is it feasible for most people? Nope.

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