What is a domain name?: Difference between revisions

Latest revision as of 16:25, 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

The 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

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-Domain names 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.
+{{done}}
+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 <tt>yoursitename.bravehost.com</tt>.  If you have a professional account, you get one free domain name, and can purchase more as you need them.  This means that you can have <tt>yoursitename.com</tt> point to your site.
+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>
-====How do I get one?====
+==Getting a Domain==
-See [[Registering a domain]] for information on signing up for a domain name, and our main [[Domains]] section for more information on transferring domains or using external domains.
+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]]'''.
-====Details====
+==How Domains Work==
-Please see [[Understanding Domain Names]] for more details.
+{{main | How the domain name system works}}
-=====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 can 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.
+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.
-=====Valid domain names:=====
+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.
-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 history of the internet. Originally labels had to start with a letter, and end with a letter or digit; any intervening characters could be letters (a-z), digits (0-9), or hyphens ( - ).  Currently it is possible for a label to start with a digit and have underscore ( _ ) characters in them, but support for these labels is uneven.
-Labels must be at least 1 character, and under 64 characters long. Letters are ASCII, and allow both upper and lower case, but labels are compared case-insensitively - so www.BRAVENET.com and www.bravenet.com are considered the same.  There is growing support for non-ASCII characters in domain names with some domain registrars, but it is still very highly recommended that you stick with the guidelines above, otherwise you stand the chance that large portions of the internet will not be able to visit your domain.
+This is a bit of a simplification, but it gets the general process across.
-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.
+===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.
-=====How does it work?=====
+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.
-When looking up a website (for example hostingwiki.bravenet.com) by domain name, the domain name is broken up into individual labels (in our example: hostingwiki, bravenet, com are the labels). Starting at the right-most label, your computer asks "who is responsible for this label?" There is an implied '.' at the end of the domain name, and that blank label, or root domain, is examined first.
-There are a group of 13 root domain servers on the internet which your computer queries.  Those root servers tell you where to check for more details about the "com" label - also known as a top level domain.  The servers responsible for these top level domains, for example .com, .org, .net, or the country-based .ca, .uk, .tw and so on, then tell you where to look for more information about the label "bravenet".  Your computer then queries the appropriate server, and is told to look at our DNS server to find information about the label "hostingwiki".  Finally, your computer asks our server for the details for hostingwiki.bravenet.com - and it gets an IP address pointing to the exact right server for this wiki.
+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.
-In reality, most of this information doesn't change very often, so it is cached at multiple levels.  Your computer will never have to ask the root server, or even a top level domain server about this information, because your internet provider will likely have already gathered and stored that information for you.
+==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:
-==How to Get There==
+* Be composed of only the letters a to z, the numbers 0 to 9, and dashes (-)
-# Visit [http://www.bravenet.com www.bravenet.com]
+* Not start with a dash (-) character
-# Log into your account, or create one if you don't have one yet
+* Not contain any special characters, or accented letters
-# Select the [[Image:Domains.JPG]] tab to manage your domains
+* 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]]