ptr ns lookup

ptrns

#!/usr/bin/php
<?php

//PTR nameserver lookup

if (!isset($argv[1])) { exit(); }

$ip = exec("dig " . $argv[1] . " A +short");

$ip = explode('.', $ip);

$reverse_zone = $ip[2] . '.' . $ip[1] . '.' . $ip[0];
$reverse_zone = $reverse_zone . ".in-addr.arpa";

exec("dig in ns " . $reverse_zone . " | grep -E \"" . $reverse_zone . ".*NS\" | grep -v \; | awk '{print $5}'", $output);

if (empty($output)) {

    echo "No reverse record set." . PHP_EOL;

} else {

    echo "PTR ". $reverse_zone . PHP_EOL;

    $output = implode(PHP_EOL, $output) . PHP_EOL;

    echo "Nameservers:" . PHP_EOL . $output;

}