There are two things that are required for a site to answer properly in DotNetNuke.  The first is proper resolution of DNS to the location of your DNN site (which you seem to have).  The second is a DNN setting which is a Portal Alias for the specific address used to reach the site.  What usually happens is that folks will install DNN on a local system or using a non-production url (often simply "localhost" on a local machine) and when they migrate to a production environment they have a url which resolves properly to the DNN instance, but which has not been configured as a portal alias.  DNN simply defaults to the first site listed in its portal alias list (you can have as many as you want) which, in your case, is likely "localhost".

Scott Willhite, Co-Founder DNN