270 front end servers sounds absurd for the TripAdvisor model.<p>700k requests per minute is ~12k requests per second.<p>I've had a sustained 4k-5k on a single un-optimised instance of nginx.<p>TripAdvisor pages are obviously hugely more complex but a lot of the processing will be happening in the middle tier / back end servers. Most of these front-end requests should be trivially cacheable - static content served to anonymous users, images, CSS and the like.