I was intrigued when an application that uses caching extensively showed a lot of loaded resources at the application level, as image below. At the service level, and in my logs, there are only some few hundreds per minute at the peak, so I'm figuring Dynatrace is counting all resources referenced in the page, and not only those that are being downloaded. Can someone confirm this?
For me it is logic as the measures is done by Dynatrace RUM at client level (browser) so they track all calls to get ressources from the browser and can't know if it was cached by a CDN for instance.
Yes, Dynatrace knows if the object was loaded from the network, or the local cache. And it certainly knows about CDNs & 3rd parties.
Regarding the local cache, you can even see it in the RUM waterfall, as the two examples below. The first one has transmitted data, and the second not: