I do not know when you have done this, but it can take a couple of hours (up to a day) before DNS changes take effect.
What you can do is a wget from the commandline on your server:
wget
http://www.hokpok.com
or
wget
http://hokpok.com
or
wget
http://yourip
If this doesn't work, there surely is something wrong with your webserver.
Have you tried with just an index.html (with some text) to see if that works? To see if apache is set up correctly?
Next step info.php file (<?php phpinfo(); ?>) to see if php is set up correctly.
Restarted apache?
I am learning how to set up a webserver with nginx, so this is probably as far as I can help you.