ASP.NET not working with DNS name

Hi,

I have asp.net web application using windows authentication. The website is running in IIS7. 

Server Name: MyServer01 

DNS Name: Intranet (This name "Intranet" is pointing to IP address of MyServer01)

So when the users access the website by using DNS Name, the credential popup will be shown.

However, when accessing by using a server name, it works fine.

Please advise.

Thanks,

Brew