When trying to access a named based VDS using the Shared IP as a prefix, the page initially appears but once you refresh the page, there is error: 404 a page not found.
When the domain name is not resolvable, there is an option to use a Shared IP before the domain in the URL to see the site.
When trying to access the link http://[Shared IP Address]/[Domain Name]/ at the first time, the http request is being translated to the SAPROXY process, which re-routes the address to the right VDS and therefore the page is displayed correctly.
The next time, when the user will try to refresh the same page, the request is being forwarded through the apache and because the VDS does not resolve, the error appears. It will take several minute until the next request will be forward through the saproxy again.
Note, this feature is working as design, and the ability to access the site before it resolve using this method is only temporary.