CDNs throwing data off?

[tomByrer]

Third party CDNs can serve a cached, more local, thus faster, copy of a website. wouldn't Wouldn't that make your data inaccurate, since it would be random what sites are hosted + are CDN cached, while other sites don't use a CDN?

For example, for a client I was planning to add CloudFlare to their Weebly site. To do so, I would switch their DNS record from Weebly's IP to CloudFlare, then CloudFlare would request Weebly. IIRC, the first few requests through 1 of CloudFlare's 100+ POPs would have to request a new copy since it wasn't cached, but subsequent visits would be faster via the closer POP. But not all Weebly's traffic runs though ClouldFlare. Likely few will. But likely a larger percentage of GoDaddy's WordPress admins would use a CDN, that could skew numbers in that direction, even if Weebly's raw hosting stats are faster.

You could test for CloudFlare via their cf-cache-status &/or cf-ray headers. But there are many more CDNs out there, a few CDNs a friend tests are here.

Note: It could be possible that ALL traffic for a particular host. Or CDNs are atomically available at higher tiers. Or someone configured their site to use an Image CDN, Google Fonts, & jsDelivr for JavaScript plugins....