CDN Drupal is altering URLs so that your static content wouldn’t be loaded from your origin server but from CDN servers. It provides two modes: “Origin Pull” and “File Conveyor”. For setting up with our CDN you need to only use Origin Pull which is basically used as domain name rewriting mode.
Installing Drupal CDN
Login to your Drupal Admin Panel, click “Modules”, then click “Install new module”.
In the “Install from a URL” box, input the CDN Module URL: http://ftp.drupal.org/files/projects/cdn-7.x-2.5.zip which can be obtained from the official Drupal CDN Project Page, and click “Install”.
Now click on “Configuration”, then scroll down to click on “CDN”. In the General Tab, tick the “Enabled” Radio Box then click “Save Configuration.
Click on the “Details” then select “Origin Pull”. For the “CDN Mapping” box, enter the CDN URL in the following format: http://foo.bar.netdna-cdn.com
Please note that the URL should be replaced with the original CDN URL you have
Click “Save Configuration”.
After this your website is officially using CDN services which you can confirm by loading your website and viewing the page source. If your Origin URL is rewritten to CDN temp URL you are all set.