<?php

	$prefered_nameservers = ["NS1.GOOGLE.COM", "NS2.GOOGLE.COM"];

	$domain = $_GET["domain"];

	$nameservers = [];

	$records = dns_get_record($domain, DNS_NS);

	if ( is_array($records) && count($records) > 0 )
	{
		foreach ( $records as $record )
		{
			$nameservers[] = strtoupper($record["target"]);
		}
	}

	asort($nameservers);

	$nameservers = array_values($nameservers);

	if ( empty($nameservers) )
	{
		echo "Couldn't fetched DNS information.";
	}
	else
	{
		$_tmp_nameservers = $prefered_nameservers;

		foreach ( $nameservers as $index => $nameserver )
		{
			if ( count($_tmp_nameservers) > 0 )
			{
				if ( in_array($nameserver, $prefered_nameservers) )
				{
					unset($_tmp_nameservers[$index]);
				}
			}
		}

		if ( count($_tmp_nameservers) <= 0 )
		{
			echo "DNS information is matched.";
		}
		else
		{
			echo "DNS information isn't matched.";
		}
	}