I'm using Apache 2.2.20. I set the expire_mod to become "access plus a few minutesInch. I look into the header with a couple website, and i'm certain within the header there did comes with an expire directory. However, after i make use of a tcpdump to watch the network traffic, I still begin to see the packet transfer after i reload the web page while using Opera, which shouldn't be expired. Does anybody know the reason behind this? Thanks.

Whenever you hit the "reload" button of the browser, the browser assumes it need and reload all aspects of the page.

You've mod_expires set up properly. However, this will not steer clear of the browser trying: whenever you hit the reload button, a request each element is going to be sent anyway, having a If-Modified-Since header, consider, around the Apache side, it has not been modified, Apache will return a 304 Not modified.

So, you do see traffic, simply not a complete page reload. You are able to witness this with similar tool you accustomed to capture the headers to verify keepalive is working (and incidentally, a a few minutes max-age is low).