You might want to give Net::Ping::External a try. From its docs:

... this module will probably provide more accurate results than Net::Ping will. Why? ICMP ping is the most reliable way to tell whether a remote host is alive. However, Net::Ping cannot use an ICMP ping unless you are running your script with privileged (AKA "root") access. The system's "ping" command uses ICMP and does not usually require privileged access.