i have a ubuntu server with apache setup, the main domain on the server is a subdomain app.example.com, which is working fine, now if i setup john.app.example.com, then that also is displaying the web page of app.example.com, the DocumentRoot for john.app.example.com is different, still it shows the web page of app.example.com. how can i resolve this, so john.app.example.com displays the pages that are there in its DocumentRoot.