About subdomains

Subdomains are lower-level domains hosted on a registered root domain.

For example, if you own the root domain name example.com, you can host a subdomain, sales, on your root domain. Users can access the subdomain, by typing the subdomain URL, sales.example.com, in a browser just as they do example.com. You do not need to register the subdomain, since it is based on your registered root domain name.

http://	subdomain	.	example	.	com
	3rd level domain		2nd level domain		Top-level domain or 1st level domain

Subdomains enable you to organize and position Web data and services into distinct online channels. Supporting business units, separate product lines and diverse geographies of enterprises can be effectively web-managed as subdomains.

Note: To create subdomains, your service provider must enable subdomains for your site. You can add subdomains to name-based as well as IP-based sites. The number of subdomains you can create is also set by your service provider at the time of creating your site.

Advantages of subdomains

Subdomains offer the following advantages:

Reinforce branding and Web presence

Subdomains enable you to create distinct online service channels for affiliated business data and services while preserving brand association. This reinforces brand value and extends your Web presence through alternative channels of service.

Simplify management of large domains

Large domains can be split up into separate logical entities in alignment with your organizational setup and web-managed separately. Thus, your enterprise can have a separate yet affiliated Web presence for sales, support, human resources, and other business divisions apart from your primary Web site.

Independent private online repository of content

Each subdomain has its own private repository of online content resources. The subdomain folder contains all the content resources necessary for the subdomain to be accessible from a Web browser. This segregation averts content or resource violation and ensures secure management of subdomain content.

The subdomain environment

Subdomains, at the file system level, are simply subfolders that contain the requisite Web content for the subdomain.

You can create two types of subdomains:

Regular subdomains

Regular subdomains can be created using the Add subdomain option. Regular subdomains can be located anywhere in the site's file system within the subdomain base directory.

All the regular subdomains for the site are, by default, placed in the /var/www directory, also called the base directory. Your service provider sets the base directory.

For example, if /var/www is the base directory set by your service provider and you create a subdomain, mysubdomain, then your subdomain will be located at /var/www/mysubdomain

User subdomains

User subdomains can be created using the Add User option. A user subdomain is a subdomain that has the same name as its owner. The subdomain will, by default, be located in the home directory of the user under the public_html folder. The subdomain directory cannot be changed by the user.

For example, if you enable a user subdomain for the user, myname, then the user subdomain will be called myname and will be located at /home/myname/public_html/

Subdomains inherit the security level and aliases defined for the root domain. The security level inherited by the subdomain will determine the operating environment of the subdomain. You can enable CGI Support for subdomains to enable users to run CGI scripts.

Aliases

Aliases are nicknames or alternative web addresses that map to an existing subdomain. Subdomains inherit the aliases configured for the root domain. To determine if aliases are available for the subdomain, see the URL field in the Subdomains Details form. You will find the subdomain URL along with the list of aliases (if the root domain has aliases).

Note: You can access subdomains using aliases only if the root domain has aliases configured.

If your root domain, example.com, is configured to be accessible using the alias, example.net, then the subdomain, sales, hosted on the root domain can also be accessed using the alias, sales.example.net.

CGI support

CGI scripts enable you to capture and process information dynamically. They can be used to retrieve information from a database, collect Web statistics and perform searches.

CGI scripts are placed in the cgi-bin directory under the subdomain folder. Hence, if the subdomain, sales, is located within the /var/www/sales/ directory, then the CGI scripts for the subdomain will be placed in the /var/www/sales/cgi-bin/ directory in the root domain's file system.

To run a subdomain CGI script, in the Address field of your Web browser, type the following:
http://<subdomain_name>.<domain_name>/cgi-bin/<script_name>
where:
<subdomain_name> is the name of your subdomain
<domain_name> is the domain name of the site on which your subdomain is hosted
<script_name> is the name of the cgi script

As a Site Administrator, you can:

Create subdomains for a registered domain
View current subdomain details
Change subdomain settings
Set default subdomain settings
Delete subdomains

Before creating a subdomain

Before creating a subdomain, have the following information ready.

Name of the subdomain - Choose a name for your subdomain.
Full directory path of the subdomain - The name of the directory where all the required content resources for the subdomain will be located.