How to ping the other systems

hi,
i have been asked to get the information of the systems in the network by executing ping in perl programming.

use Net::Ping;
$p = Net::Ping->new();
print “$host is alive.\n” if $p->ping($host);
$p->close();

where $host–> is the ip of the destination machine. if i try to give the loopback or ip of my machine then its working properly. but if i try to give ip of the some other machine conneted to network then ping will not work.
But ping using command prompt is working properly for any machine in the network.
Is there anybody to help me out…