You can measure the CDN cache effeciency based on the ratio of successful requests (hits) to unsuccessful ones (misses) using the following formula:
Cache hit ratio = [Hits / (Hits + Misses)] x 100 %
Due to the nature of CDN technology, it is impossible to achieve 100% ratio. However, the higher the percentage, the more effective the cache is. You can influence the efficiency of the CDN by setting Cache-Control header or forcibly caching all static content in the CDN web interface. It is worth noting, that long cache validity causes changes on the source server to propagate more slowly.
You can check the statistics for your website by clicking the "show" for the domain you are interested in.
It opens a detailed view with the following items:
- Basic information about domain
- Total amount of transferred data, successful and unsuccessful requests and their ratio.
- Historical overview of the statistics