Caching CORS, Cache poisoning and the Vary HTTP header Understanding the Vary header is key ensuring CORS will work with CDNs and caching.
Cloudflare Analyzing Cloudflare Logs (formally ELS) with the command line If you have an enterprise zone with Cloudflare, there is the ability to request the raw request logs using 'Cloudflare Logs' (formally called Enterprise Log Share or ELS for short).