Not exactly sure what you mean by sub-domain. If you are referring to host-headers, then the answer is quite simple.
First off...
host headers:
is the domain name.
is the host header for a second web site attached to the abc.com domain name.
There are three ways to seperate web sites on your server. One is by having a different IP address. Another is by having different port numbers. And the third is by assigning different host headers.
You have create the web site:
and hold it in your c:\inetpub\
folder. In the host headers in your IIS, have the host header read "
then create another one for the same site called "abc.com". This way, anyone can type
OR abc.com to reach your site.
Create anther site under the c:\inetpub\mySite\ folder and have it assigned to the same port (80) and IP address, but have the host headers for the site read, "mySite.abc.com". Continue this for all the sites you want to create under the same domain. Now when someone types
they will go to the site in c:\inetpub\
but if they type
they will go to the site under c:\inetpub\mySite\!
Hope this helps.
-Ovatvvon :-Q