Headers returning x-cdn-cache-status MISS indicate the request was served by the origin D2M Hosting server. This means that the response was not found in the cache and so was fetched from the origin server, resulting in a longer TTFB and a longer total load time. On pages you want to be cached you'd expect to see x-cdn-cache-status HIT.
A cache 'MISS' status is usually caused under three main conditions:
- Browser cookies being set
- Conflicting caching plugins
- Preventative .htaccess file directives
Browser cookies
When a cookie is in use on a webpage the CDN edge cache will automatically avoid caching the content. When present, cookies work with PHP as the page is loaded in order to perform a unique action. When a page is served from cache, it’s already been generated previously by the server. If the page is cached, the cookie cannot be generated and perform its action with the page load as expected.
Some applications also use a PHPSESSID cookie which busts cache as the page will automatically receive a cache, MISS, for example, WooCommerce set's a PHPSESSID. In a lot of cases this cookie doesn't alter behaviour, so disabling the cookie is one way to correctly optimise and configure your site to work best with the cache. You may wish to try adding into a php.in file session.use_cookies = 0, if this doesn't work the following code in your .htaccces file should also achieve the same result in disabling the PHPSESSID SetEnv session.use_cookies='0';
Let's take a real-world example. If you have a WordPress website with a shopping cart, you'll almost certainly have a cookie storing data about what product Customer A has in their basket. If this data was cached at a CDN node and served to Customer B, they too would see the same product in their own basket.
Conflicting Caching Plugins
Our platform comes with various layers of caching built-in. One of the most effective of these caching layers, especially at scale, is our edge cache system.
Unfortunately, most cache plugins will interfere with this and as a result, we don't recommend running any caching plugins on your WordPress site.
This includes, but is not limited-to: W3TC, Super Cache, WP Rocket and Hummingbird.
Don't panic! You won't need them - all caching plugins are built for speed, and you can rest assured our StackCache plugin will do that hard work for you.
.htaccess File Directives
Cache-Control and Expires headers can be set in the .htaccess file within the root directory for the site. These let you control various elements of how your site is cached, including preventing caching altogether.
If you were to add Cache-Control: no-store into a .htaccess file then the HTTP headers would serve as a directive to prevent the site from caching and a cache MISS would be received via the HTTP headers.
If you receive a cache MISS then you should review your .htaccess file for any conflicting directives.
