One of Marfeel's main objectives is to maximize the revenue generated from the ad spaces sold. 

To this end, Marfeel offers an optional configuration that selects an ad server based on ad type, layout position, or user type for the ad to be served, even though in most cases this is done directly by the customer's ad server. 

This configuration is done directly from JavaScript to avoid delays introduced by the AdServer and helps avoid an entire round trip to the server.