Is there a command or a service that will tell me whether my websites are being served over HTTP or HTTP/2.
I found this tool: HTTP/2 Test | A simple HTTP/2.0 test tool, but it only tells me whether my website supports HTTP/2, but not whether it is already using HTTP/2.
These is also this Chrome Extension: HTTP/2 and SPDY indicator, which tells me that HTTP/2 is already enabled on my site, but as far as I know my version of Apache doesn't even support it.
Is there any way to know for sure? Thanks!
Apache doesn't have to support it. The Chrome extension reads the HTTP headers to determine that.
Another method is simply to look at the network tab > headers > response headers > view source in Chrome or Firefox. There the headers can be seen. It should read "HTTP/2" or some sort I can't recall right now.
Easiest: You can use curl -I <your site> which will put the HTTP response as the first line.
HTTP/2.0 200
server:nginx
date:Fri, 29 Apr 2016 14:31:40 GMT
content-type:text/html; charset=utf-8
content-length:7629
last-modified:Thu, 07 Apr 2016 02:41:08 GMT
....