mjhjmtu

OS: Ubuntu 16.04

Installed with ISPConfig 3.1 (followed the how to: https://www.howtoforge.com/tutorial/perfect-server-ubuntu-16.04-with-apache-php-myqsl-pureftpd-bind-postfix-doveot-and-ispconfig/)

I'm running several clients on my server with different kind of CMS solutions i.e. Wordpress, Joomla, Prestashop etc. all running PHP that I found I could optimize performance wise with Apache's mod_cache (cache_disk and file_cache). I found different articles pointing me to a final configuration that looks like the following.

<IfModule mod_cache_disk.c>
 CacheRoot /var/cache/apache2/mod_cache_disk
 CacheEnable disk /
 CacheDirLevels 2
 CacheDirLength 1
 CacheQuickHandler off
 CacheLock on
 CacheLockPath /tmp/mod_cache-lock
 CacheLockMaxAge 5
 CacheIgnoreHeaders Set-Cookie
 CacheDisable /wp-admin

 <Location />
 CacheEnable disk
 CacheHeader on
 CacheDefaultExpire 900
 CacheMaxExpire 86400
 CacheLastModifiedFactor 0.5
 ExpiresActive on
 ExpiresDefault "access plus 15 minutes"
 Header merge Cache-Control public
 FileETag All
 </Location>
</IfModule>

With this configuration I am able to optimize performance 20% on my setup for a simple Wordpress solution.

Everything looked good until I stumbled upon a prestashop client. The situation was that every single page/link was showing the same content as the first visit until the cache was cleared. URLs were changing but the content stayed the same.

My question is, how this can this behavior be avoided and if I can tune my configuration to suit more widely on dynamic content so that i don't have to worry about speciel cases?