How to redirect everything to 404 not found? I need to block an entire Drupal 7 site from being indexed for a while. So, I think it is best to redirect everything to 404 instead of actually deleting all my files. How can I do that?

PS: using the following code on .htaccess does not seem to work.

RewriteEngine On
RewriteRule ^ - [R=404,L]


-- Update 03/04/2015 -- 
The server is nginx
If you are just trying to keep it from being indexed, you can just add

User-agent: *
Disallow: /


To the top of your robots.txt