According to sstatic.net:
This is a fast, cookieless domain intended for static content delivered to the Stack Exchange family of websites
However, all responses from the server set a cookie anyway:
$ http https://sstatic.net/ HTTP/1.1 200 OK CF-RAY: 162b88245bc406be-LHR Cache-Control: max-age=604800 Connection: keep-alive Content-Encoding: gzip Content-Type: text/html Date: Sun, 31 Aug 2014 19:11:04 GMT ETag: W/"d5474fdfb5c3cf1:0" Last-Modified: Fri, 29 Aug 2014 18:20:12 GMT Server: cloudflare-nginx Set-Cookie: __cfduid=db60cc6f3e7f6482e37f1f2b85c9dc5881409512264375; expires=Mon, 23-Dec-2019 23:50:00 GMT; path=/; domain=.sstatic.net; HttpOnly Transfer-Encoding: chunked Vary: Accept-Encoding [...]
Is this intentional, or just funny?
Edited to add: I understand that the cookie is used to track visiting browsers so that cloudflare can distinguish them from misbehaving hosts using the same or a nearby IP address. However, if the policy is intentionally to serve cookies, then the self-documentation of sstatic.net as a "cookieless domain" is incorrect.