When a browser send a request to an apache web server, apache will send back the response data as well as response headers. You can check what kind of headers are send back with curl command.
$ curl -I http://mysite/
or if the site is on https
$ curl -Ik https://mysite/
Date: Mon, 07 Dec 2015 10:12:52 GMT Server: Apache X-Powered-By: Phusion Passenger (mod_rails/mod_rack) X.X.XX Cache-Control: no-cache