Changing default / index page via htaccess

If your working on a site and would like visitors who access yoursite.com to be redirected (instantly) to a maintenance or under construction page instead?
It can be done by editing your .htaccess file to include the following code. Here’s what you have to do. Add this to your .htaccess file:

DirectoryIndex under_construction.html

This will treat “under_construction.html” as your default page instead of your “index.html” file.