This is a simple project to show that you can send a variable value to a PHP script and then print out the results.
ping.html you submit a domain name or IP ddress and this is sent to the ping.php script
ping.php turns the url/ip address into a variable, and then uses the shell_exec() function to ping that variable value
the response is then printed on the screen, and using strpos() it evaulates whetehr "Destination Host Unreachable", and if so prints $address." is down"