Subdomains are the third level domains that are used to organize
your Web site content. They are just like folders under your root directory,
with a special URL to access them.
Open the Site Administrator Home
page.
In the IIS
Web Service area, click Subdomains.
Click Add
Subdomain. The Add Subdomain
form displays.
In the Subdomain
Name text box, enter a name for the subdomain.
Note:
The parent domain name, (displayed next to the text box) is appended
to the subdomain name.
For example: Domain name 'mydomain.com'
is appended to subdomain 'mysubdomain',
thus a subdomain named 'mysubdomain.mydomain.com'
is created.
Click Add.
The subdomain is added and is displayed on the View
Subdomain page.