my @host = qw[ 192.168.15.2 192.168.16.2 192.168.17.2 192.168.18.2 ];
my $stout;
my $counter = 0;

while ($stout = run($host[$counter])) {
  last unless $stout == 256;
  if ($counter < $@host) {
    print "$host[$counter] not responding, trying $host[$counter+1]\n";
    $counter++;
  } else {
    print "$host[$counter] not responding, no more hosts to try.\n";
    last;
  }
}