<?php
$domain = "thurdesk.ch";
$host = "office." . $domain;
const NS1 = "185.163.51.142";

require_once 'Net/DNS2.php';

function cwp7CheckA($host, $serverIP, $nameserverIP, $recurse = 0) {
	if($recurse > 3) {
		return false;
	}
	$nameserver = array($nameserverIP);
    # try NS1
    $resolver = new Net_DNS2_Resolver(array('nameservers' => $nameserver));
    try {
        $result = $resolver->query($host, 'A');
        print_r($result);
        return true;            
    } catch(Net_DNS2_Exception $e) {
    # try default nameserver
        $resolver = new Net_DNS2_Resolver();
        try {
            $result = $resolver->query($host, 'A');
            print_r($result);
            return true;            
        } catch(Net_DNS2_Exception $e) {
            return "lookup error";
        }
    }
	$hostA = $result->answer;
	if($hostA[0]->type == 'CNAME') {
		if(cwp7CheckA($hostA[0]->cname, $serverIP, $nameserverIP, $recurse++)) {
			return true;
		}
	}
	if($hostA[0]->type == 'A') {
		if($hostA[0]->address == $serverIP){
			return true;
		}
	}
	return false;
}

function cwp7CheckSOA($domain, $nameserverIP = NS1) {
    $nameserver = array($nameserverIP);
    # try NS1
	$resolver = new Net_DNS2_Resolver(array('nameservers' => $nameserver));
    try {
            $result = $resolver->query($domain, 'SOA');
            return 'self';
    } catch(Net_DNS2_Exception $e) {
    # try default NS
    	$resolver = new Net_DNS2_Resolver();
        try {
            $result = $resolver->query($domain, 'SOA');
        } catch(Net_DNS2_Exception $e) {
            return 'none';
        }
    }
	return $result->answer[0]->mname;
};

$result = cwp7CheckSOA($domain);
print_r($result);
if(cwp7CheckA($host, "5.226.148.139", NS1)) {
    echo "success";
};