Hi,
At http://www.balancedview.org/en/ we have implemented cloudfront as CDN and looking at the HTML code one can see that relevant resources are mapped to CDN correctly and yet WPT keep telling us that CDN mapping is not done for most of the resources. Please refer to the test result here: http://www.webpagetest.org/result/130709_V5_EDT/1/performance_optimization/#use_of_cdn
Best!/Gobezu
Your cloudfront resources are redirecting (with a 301) to your origin domain: http://www.webpagetest.org/result/130709_V5_EDT/1/details/#request32 so the images are not actually being served by the CDN.
I can’t imagine that’s what you actually intended. My guess is that your origin mapping for the CDN is pointing to the wrong domain (maybe the bare domain) and is getting redirects as a result.
If you check your server’s access logs my bet is that you will still be seeing way more requests for the static resources than you’d expect if the CDN was working.