The phpinfo() function is invaluable for getting information about what is happening with the PHP configuration and loaded modules.
Find the document root for your domain. You can do this in cPanel by clicking on the Domains icon and checking the table where your domain is listed.
Create a file named phpinfo.php with the following contents inside of your domain's document root:
Then visit the file and view the contents:
You may also want to verify that the domain is pointed to your server's IP address. You can learn how to check this in the following resource: