my %hosts;
my $ip = qr/\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}/;
while(my $line =<>){
  chomp $line;
  if($line =~ m/for (.*)$/){
    my @f = split /\s+/, $1;
    if(scalar(@f) == 1) {
      $hosts{$f[0]} = $f[0];
    } else {
      $f[1] =~ s/\(//; $f[1] =~ s/\)//;
      $hosts{$f[1]} = $f[0];
    };
  };
};
foreach my $k(map substr($_, 4) => sort map pack('C4' => m/(\d+)\.(\d+)\.(\d+)\.(\d+)/) . $_ => keys(%hosts)) {
  my $v = $hosts{$k};
  if($v =~ $ip) {
    print "$v is up\n";
  } else {
    my $r = `host $v`;
    my @l = split /\n/, $r;
    my $resolve;
    foreach my $i(@l) {
      if($i =~ $ip) {
        my @f = reverse(split /\s+/, $i);
        $resolve = $f[0];
        $resolve =~ s/\.$//;
        last;
      };
    };
    if($resolve) {
      print "$k is up, has PTR $v, " . ($resolve eq $k ? "forward for that name matches\n" : "but forward for that name resolves to $resolve\n");
    } else {
      print "$k is up, has PTR $v, unable to resolve forward for that name\n";
    };
  };
};