use crontab and ping
this can be done with any scripting language
bash, and php 🙂
$reply = exec("ping -c 1 host");
if the last 3 figures are 0 , the server is down ... check them with $arr = split($reply)
$num = count($arr);
if($arr[$num-2] == 0) echo "server not responding";
but I do not know how to bell ....
maye an exec() and a command tha bells ... I know that G is the bell sign ctrl-g, but do not know how to call it from php ...
hope this helps