A third party (CDN provider) can easily track visits entirely server-side across all of the sites that it serves. Typically this is sites owned by lots of diffe

A third party (CDN provider) can easily track visits entirely server-side across all of the sites that it serves. Typically this is sites owned by lots of different companies users could otherwise visit without any of those companies knowing of visits to any other companies' sites -- the CDN knows. This also comes up when the CDN handles SSL termination.