Ok, so 2 of my previous questions got locked (even though damoncloudflare tried to help and answer) because it's off-topic and it's too broad and it's asking too many questions in a single question.
How am I supposed to ask a question how various CDNs handle a specific HTTP header?
I need to find out from people with experience and/or knowledge how Akamai, Cloudflare, Edgecast and Cloudfront handle
Vary: User-Agent header.
It is about a website that I control. It is about 1 very specific http header and 4 very specific CDN services. http://webmasters.stackexchange.com has CDN tag with 110 questions tagged so it, so it's not offtopic here. So what magic combination of words should I use for this question to be allowed?