I'm experiencing a caching issue I can't explain. This is happening across browsers, IPs and ISPs. If a user force-refreshes, they see the new content. If they then refresh or return to the page, the old one displays. I've tried using headers via PHP such as
header( 'Expires: Sat, 26 Jul 1997 05:00:00 GMT' ); header( 'Last-Modified: ' . gmdate( 'D, d M Y H:i:s' ) . ' GMT' ); header( 'Cache-Control: no-store, no-cache, must-revalidate' ); header( 'Cache-Control: post-check=0, pre-check=0', false ); header( 'Pragma: no-cache' );
Laid out correctly, at the very beginning of the file. The problem persists. A pan-ISP proxy is unlikely. Suggestions?