What is a domain name?: Difference between revisions

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<p>Domain names are hostnames that provide more easily memorable names to stand in for numeric IP addresses. They allow for any service to move to a different location in the topology of the Internet (or another internet), which would then have a different IP address.</p>
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Domain names (frequently just called ''domains'') are names that identify a particular computer on the internet.  Examples are www.bravenet.com and www.google.com.  They act as an alias for numeric [[IP addresses]], but they are not permanently tied to a particular IP address. This means that you can change your domain name to point at a new IP address if you move your website from one computer to another.


<p>Each string of letters, digits and hyphens between the dots is called a label in the world of the domain name system (DNS). Valid labels are subject to certain rules, which have relaxed over the course of time. Originally labels had to start with a letter, and end with a letter or digit; any intervening characters may be letters, digits, or hyphens. Labels must be between 1 and 63 characters long (inclusive). Letters are ASCII A�%G–�%@Z and a�%G–�%@z; domain names are compared case-insensitively. Later it became permissible for labels to commence with a digit (but not for domain names to be entirely numeric), and for labels to contain internal underscores, but support for such domain names is uneven. These are the rules imposed by the way names are looked up ("resolved") by DNS. Some top level domains (see below) impose more rules, such as a longer minimum length, on some labels. Fully qualified domain names (FQDNs) are sometimes written with a final dot.</p>
By default, your website can be accessed at the sub-domain <tt>yoursitename.bravehost.com</tt>.  You can have have the domain <tt>yoursite.com</tt> point to your site by [[registering a domain]], in this case <tt>yoursite.com</tt>


<p>Translating numeric addresses to alphabetical ones, domain names allow Internet users to localize and visit Web sites. Additionally since more than one IP address can be assigned to a domain name, and more than one domain name assigned to an IP address, one server can have multiple roles, and one role can be spread among multiple servers.</p>
==Getting a Domain==
See the article '''[[registering a domain]]''' for information on signing up for a domain name. If you already have a domain elsewhere, you can see our information on '''[[transferring a domain]]''' or '''[[adding an external domain]]'''.


==How Domains Work==
{{main | How the domain name system works}}


<br><br><br>
Any time you refer to a domain name in any internet software, that software will look up the [[IP address]] that's associated with that domain name. It will use the resulting IP address to actually make the connection on the internet - the domain name is just used as a shorthand so that we don't all have to remember long numbers.
'''How to get there:'''
 
<br><br>
Domain names are registered in a heirarchy - different organizations are responsible for each part of a domain name.  For this example we will look at <tt>wikifree.bravehost.com</tt>.  When you type that into a browser, the browser will try to find out who is responsible for the <tt>.com</tt> part of the name (<tt>.com</tt> is what is known as a [[top level domain]]).  Once it finds that out, it'll ask who is responsible for the <tt>bravehost</tt> domain.  It will then find out that we've registered <tt>bravehost.com</tt>, so we're in the <tt>.com</tt> registry. The browser then asks our servers how to get <tt>wikifree</tt> on our domain.  Our servers will have the actual IP for <tt>example.bravehost.com</tt> and will provide that to your web browser, and your browser will now be able to talk directly to the right web server.
[[Image:Domains.JPG]]
 
This is a bit of a simplification, but it gets the general process across.
 
===Why use domain names?===
Domain names effectively translate the numeric IP addresses that relate to everything on the internet to alphabetical addresses.  This makes websites easier to remember.
 
Also, since one domain name can point to multiple  IP addresses, and multiple domain names can point to one address, and that relationship can easily be changed, domain names allow flexible addresses on the internet.  For example, if you wish to move your website <tt>www.example.com</tt> to another physical server, even though the IP will change, you could change where the domain points and still refer to the same website with the same domain name.
 
Similarly, if the role of the server changes, you can adapt your domain names to suit the changes.  For example, you start with a small website - <tt>www.example.com</tt>, and then add a forum at forum.example.com, and email services at <tt>email.example.com</tt>.  Initially, all these addresses point to one server, but if you outgrow that server, it is easy to have <tt>email.example.com</tt> point to a different server.
 
==Valid Domain Names==
{{main | Valid domain names}}
 
In general, domain names need to meet certain strict naming restrictions.  Domain names are seperated into '''labels''' seperated by '''.''' characters (<tt>wikifree.bravehost.com</tt> is composed of three labels - <tt>wikifree</tt>, <tt>bravehost</tt> and <tt>com</tt>.  Each label must:
 
* Be composed of only the letters a to z, the numbers 0 to 9, and dashes (-)
* Not start with a dash (-) character
* Not contain any special characters, or accented letters
* Be under 64 characters long (the entire domain name - including '.' characters - must be under 67 characters)
* Some top level domains have additional restrictions on their subdomains
 
Note that domain names are case insensitive.
 
There's limited support for non-standard domain names. Some registrars do offer names allowing Cyrillic and Chinese characters, but support is very spotty at this time.  Using a non-standard domain name may result in people being unable to visit your site.
 
==Resources==
* The [[:Category:Domains | Domains category]] of our wiki
* Information on [[registering a domain]]
* Information on [[using an external domain]] and [[transferring a domain]]
* Details of [[how domains work]] and [[valid domain names]]
 
[[Category:Domains]]
[[Category:Glossary|Domain Name]]

Latest revision as of 17:25, 23 May 2008

Domain names (frequently just called domains) are names that identify a particular computer on the internet. Examples are www.bravenet.com and www.google.com. They act as an alias for numeric IP addresses, but they are not permanently tied to a particular IP address. This means that you can change your domain name to point at a new IP address if you move your website from one computer to another.

By default, your website can be accessed at the sub-domain yoursitename.bravehost.com. You can have have the domain yoursite.com point to your site by registering a domain, in this case yoursite.com

Getting a Domain

See the article registering a domain for information on signing up for a domain name. If you already have a domain elsewhere, you can see our information on transferring a domain or adding an external domain.

How Domains Work

Main article: How the domain name system works

Any time you refer to a domain name in any internet software, that software will look up the IP address that's associated with that domain name. It will use the resulting IP address to actually make the connection on the internet - the domain name is just used as a shorthand so that we don't all have to remember long numbers.

Domain names are registered in a heirarchy - different organizations are responsible for each part of a domain name. For this example we will look at wikifree.bravehost.com. When you type that into a browser, the browser will try to find out who is responsible for the .com part of the name (.com is what is known as a top level domain). Once it finds that out, it'll ask who is responsible for the bravehost domain. It will then find out that we've registered bravehost.com, so we're in the .com registry. The browser then asks our servers how to get wikifree on our domain. Our servers will have the actual IP for example.bravehost.com and will provide that to your web browser, and your browser will now be able to talk directly to the right web server.

This is a bit of a simplification, but it gets the general process across.

Why use domain names?

Domain names effectively translate the numeric IP addresses that relate to everything on the internet to alphabetical addresses. This makes websites easier to remember.

Also, since one domain name can point to multiple IP addresses, and multiple domain names can point to one address, and that relationship can easily be changed, domain names allow flexible addresses on the internet. For example, if you wish to move your website www.example.com to another physical server, even though the IP will change, you could change where the domain points and still refer to the same website with the same domain name.

Similarly, if the role of the server changes, you can adapt your domain names to suit the changes. For example, you start with a small website - www.example.com, and then add a forum at forum.example.com, and email services at email.example.com. Initially, all these addresses point to one server, but if you outgrow that server, it is easy to have email.example.com point to a different server.

Valid Domain Names

Main article: Valid domain names

In general, domain names need to meet certain strict naming restrictions. Domain names are seperated into labels seperated by . characters (wikifree.bravehost.com is composed of three labels - wikifree, bravehost and com. Each label must:

  • Be composed of only the letters a to z, the numbers 0 to 9, and dashes (-)
  • Not start with a dash (-) character
  • Not contain any special characters, or accented letters
  • Be under 64 characters long (the entire domain name - including '.' characters - must be under 67 characters)
  • Some top level domains have additional restrictions on their subdomains

Note that domain names are case insensitive.

There's limited support for non-standard domain names. Some registrars do offer names allowing Cyrillic and Chinese characters, but support is very spotty at this time. Using a non-standard domain name may result in people being unable to visit your site.

Resources

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