When trying to create a host-named site collection in SharePoint 2010, you get an IIS 7 Welcome Page or a “The webpage cannot be found” error:
This error (HTTP 404 Not Found) means that Internet Explorer was able to connect to the website, but the page you wanted was not found. It’s possible that the webpage is temporarily unavailable. Alternatively, the website might have changed or removed the webpage.
You have not updated your ISS bindings.
Read this post on how to create a host-named site collection.