Sripathi Krishnan 04 December 2011 >> Point 2 is mentioned in the article, but is of no relevance at all to people who aren’t using CDNs Not entirely. You set the header Cache-Control:private, which defeats caching at all levels between the server and the browser. For example, if you are behind a corporate proxy, those images won’t get cached. If you are hosting on Google App Engine, Google’s front end servers will not cache your images, costing you more money. ISPs may have their own caches – and they wouldn’t be able to cache either.