Google Chrome offers a quick and easy way to check if HTTP/2 is supported on your SSL-enabled site.
First, visit your site in Chrome over HTTPS.
Then, open a new tab and navigate to
chrome://net-internals/#http2
There you'll see your site listed with protocol h2, confirming your site works over HTTP/2.
If you see spdy listed for your domain, this likely means you are using a CDN that does not yet support HTTP/2.