We have a Drupal -Ecommerce site which is selling about 4000 products, 4000 users per hour. How do you do scaling-out of this drupal/ubercart instalation ? Does drupal support DNS NLB ? ( Round Robin ) , Does drupal support some sort of Apache/Linux machanism for having redundadnt Webservers ( have 2 web servers for redundancy and handling escalating user load ) ?