Only a staff member could tell you the actual order of preference that apache is set to check for index files on your server, but .html is usually the one that overides everything else. For example index.html will overide index.shtml and index.php
This means your best plan is to add a .htaccess pointer to the index you want to show, so that to see the real index (which you might want to do in testing) you would have to go direct to the index.html page. Anyone going to just the URL with no page specified would see the page you specified in the .htaccess.
The following code in a .htaccess file in the public_html directory will make the page they see on visiting your URL "holding.html". When you want to go back to normal, just delete the line in .htaccess
Code:
DirectoryIndex holding.html
Hope this helps
