Enable HTTP/2 module
Apache’s HTTP/2 support comes from the mod_http2 module. Enable it from:
a2enmod http2
apachectl restart
If above commands do not work in your system (which is likely the case in CentOS/RHEL), use LoadModule directive in httpd configuration directory to enable http2 module.
Add HTTP/2 Support
We highly recommend you enable HTTPS support for your web site first. Most web browser simply do not support HTTP/2 over plain text. Besides, there are no excuses to not use HTTPS anymore. HTTP/2 can be enabled site-by-site basis. Locate your web site’s Apache virtual host configuration file, and add the following right after the opening tag:
Apache 2.4.17 ships with mod_http2. Available in Debian 9 (stretch) and Ubuntu 16.04 (Xenial Xerus) (see comments) Ubuntu 16.10 (Yakkety Yak), it brings HTTP/2 support to one of the Internet’s popular Web servers. Assuming you’ve already configured a SSL/TLS Website, this quick tutorial will show you how to quickly enable HTTP/2.
