some info regarding the hosting environment:
*******************************************
The DNN Version is: 04.05.05

.NET Framework: 2.0.50727.1433

OS is: Windows Server 2003 , 32 bit

IIS Version 6

*******************************************

so now we can start talking about the issue which I encounter.

I have created an hosting account under the domain name:

domain1.com

which means that the physical path is:

D:\inetpub\vhosts\domain1.com\httpdocs\

In the IIS level I have configured the following host headers:

something.else.com
domain2.com
domain3.com
domain4.com
domain5.com
domain6.com

So in the IIS level I have configured total 7 host headers.

I have created Virtual Directory so called site.
All DNN files are reside inside 'site' Virtual Directory.
'site' is also the name of the physical Directory.
physical path is: D:\inetpub\vhosts\domain1.com\httpdocs\site\

which means that both Virtual and Physical Directories are under the name 'site'

I have run the DDN installation while using the domain address:
something.else.com

which means that I have run the DNN installation from the following URL:

http://something.else.com/site/

every thing is OK until this point. DNN is working well when using the URL:
http://something.else.com/site/

But now I would like to create multiple Portals , I would like to have more Parent Portals.

but pay attention that DNN is reside under Virtual Directory so called 'site'

I have created Parent Portals. 6 Parent Portals:

domain1.com
domain2.com
domain3.com
domain4.com
domain5.com
domain6.com

now when I try to browse to one of the Parent Portals then I get nothing.

I have tried one of the following:

http://domain1.com/site/
http://domain2.com/site/
http://domain3.com/site/
http://domain4.com/site/
http://domain5.com/site/
http://domain6.com/site/

http://www.domain1.com/site/
http://www.domain2.com/site/
http://www.domain3.com/site/
http://www.domain4.com/site/
http://www.domain5.com/site/
http://www.domain6.com/site/

http://domain1.com/site/Default.aspx
http://domain2.com/site/Default.aspx
http://domain3.com/site/Default.aspx
http://domain4.com/site/Default.aspx
http://domain5.com/site/Default.aspx
http://domain6.com/site/Default.aspx

http://www.domain1.com/site/Default.aspx
http://www.domain2.com/site/Default.aspx
http://www.domain3.com/site/Default.aspx
http://www.domain4.com/site/Default.aspx
http://www.domain5.com/site/Default.aspx
http://www.domain6.com/site/Default.aspx

but nothing , none of the above works.

only the URL which I used while installing the DNN works.
means that only the following URL works:

http://something.else.com/site/

I have checked that everything is configured correctly in the IIS level. everything is fine.
I have checked that everything is configured correctly in the DNS level. everything is fine.
I have checked that the Virtual Directory 'site' is configured with ASP.net Version 2. everything is fine.
I have checked that inside the MSSQL table 'PortalAlias' is configured correctly. everything is fine.

Please Advice how to resolve the issue.

thanks in advanced.