use Net::DNS::Resolver;
    
my $res = Net::DNS::Resolver->new(
               nameservers => [qw(10.0.5.10)], # specify your own here
               udp_timeout => 2,
               retry       => 1,
              #debug       => 1,
          );

my $host = '123.123.123.123';

if (my $pkt = $res->query($host)) {
    for my $answer ( $pkt->answer() ) {
        my $type = $answer->type();
        if ($type eq "PTR") {
            print $answer->ptrdname(), "\n";
        } elsif ($type eq "A") {
            print $answer->name(), "\n";
        }
    }
}