Set up Browser caching with Caution to speed up your website

"If you use tech improperly , things will be messed up!"

There are good start tips for Browser caching strategy posted by HttpWatch long time ago: http://blog.httpwatch.com/2007/12/10/two-simple-rules-for-http-caching/
It works great in most of situation.

However, if you have your website more complex, such as using ajax, the post above may not be sufficient.

I found interesting post from caching on IE for caching Ajax requests:

This means that any Ajax derived content in IE is never updated before its expiration date – even if you use a forced refresh (Ctrl+F5)—which means even you add “Pragma: no-cache” header with your request.
The only way to ensure you get an update is to manually remove the content from the cache.

Detail info goes to Fact#2 of this post: http://blog.httpwatch.com/2009/08/07/ajax-caching-two-important-facts/

Another conclusion for browser caching:

“In order to ensure consistent caching behaviour with IE and Firefox you should:
Always specify an Expires header. It will normally be set to -1 for immediate expiration of HTML pages or a date well into the future for other resources such as images, CSS and Javascript;
If you want to force a page to be reloaded, even with the Back button, then use Cache-Control: no-cache, no-store”

Detail info goes to this post: http://blog.httpwatch.com/2008/10/15/two-important-differences-between-firefox-and-ie-caching/

How to set up Cache-control and Expire header on Apache web Server based on your derision and deep understanding of your application:
http://www.askapache.com/htaccess/speed-up-your-site-with-caching-and-cache-control.html