use LWP::UserAgent;
$ua = new LWP::UserAgent;
$ua->agent("AgentName/0.1 " . $ua->agent);

my $req = new HTTP::Request GET => "http://some.server.net/";
my $res = $ua->request($req);

if ($res->is_success) {
   #server is alive, do something
}
else {
   #something wrong, do something
}