Ok, so by now you know that DotNetNuke can handle multiple websites, but you still want to know why. Well, it’s pretty easy once you know how to do it, but it can be pretty confusing to some who are still trying to figure out the pieces because there are a couple things that need to happen. Like always, there is always more than one way to accomplish anything, so you may be exposed to a lot of ways to do this and you could end up more confused than you started.
Basically, it all boils down to this: 1) The request for www.domainB.com has to know how to find your DNN website and 2) Your DNN Website has to know that it should be expecting the request.
In the articles, Using DNN to take Advantage of GoDaddy Domain Names, you learn how to point a domain hosted out side of your webhosting company to your website’s hosting account. And in, Setting up Multiple Websites, you learn how to configure the web hosting account to work with a new domain name for your site. Now, last but not least, you’ll learn the final step to set up DotNetNuke to accept and serve requests for the new domain.

Log in to your DNN website as the site host and navigate to the “Portals” tab on the Host menu. On the Portals page, click on “Add New Portal”. For more information about the difference between a parent and child portal, review Setting up Multiple Websites

After you have provided the information, click on “Create Portal” and you will receive the status confirmation on the top of the page:

And that’s it! Now, requests for your additional domains can be responded to by your DotNetNuke installation. Please note, the portal above was created for “www.thebamafan.com”. If I also wanted DotNetNuke to respond to requests for “bamafan.com” (no’ www’), I would need to additionally create an “Http Alias” for the new portal.