Web caching not working

Question

Hi all. 
 I have my UTM setup with web filtering and caching enabled (all 3 tick boxes) 
 I also scan with AV and have a series of exceptions where I have checked that caching was unticked (ie. Don't skip caching) but I'm finding if I look in the web filter log ... I've inly seen ever 1 or 2 entries where it has cached=1 most if not all of the time it's cached=0 
 I've tried refreshing simple pages in different browsers/computers. Even a test file download doesn't seem to be caching. 
 There is limited settings for the web caching so I really don't know what to check. I don't even know if the cache is being filled. 
 I have a 64gb disk with 4gb ram so space shouldn't be a concern. Can anyone help me?

Michael Dunn · Accepted Answer

Web Caching works in very limited scenarios and is actually fairly complicated. 
 Caching depends three things (well actually a lot more) - 1) the server says the page is allowed to be cached 2) the browser requests a cached version 3) and the browser is not doing any caching on its own 
 Most single-user scenarios that the browser and server allow caching, the browser does the caching for you so the proxy's cache never comes into play. 
 Here is a test: 
 Create a bookmark for www.example.com . 
 Use the bookmark to load the page. 
 Use the bookmark to load the page again. 
 Note that in the proxy log there is no second request because it was cached by the browser. 
 Now hit F5 to reload www.example.com. 
 Note that in the proxy log there is now another request but it was not from cache. The status code is 304. In this the browser said "GET this page, by the way I have cached version x" and the website replied 304 Not Modified with no content saying the browser cache was good. The proxy does not interfere. 
 Now clear the browser cache (you can use Control-Shift-Delete). 
 Use the bookmark to load the page. 
 You should see the request in the log and it should come from the cache.