修复与更新：改变了DNS接收解析的方式，能够适应GoogleDNS、CloudFlareDNS请求时夹带DNSSEC的请求

test.php

@@ -1,20 +1,48 @@
 <?php
-#print_r(dns_get_record('icu',DNS_SOA));
-$url='al.c919.n3n.com.cn';
-while(true){
-preg_match("#\.(.*)#i",$url,$match);//获取根域名
-$domin = $match[1];
-print_r($domin);
-$soa=dns_get_record($domin,DNS_SOA);
-if(array_key_exists('0',$soa)){
-    if(array_key_exists('mname',$soa[0])){
-    print_r($soa[0]);
-    break;
-    }else{
-        $url=$domin;
-    }
-}else{
-    $url=$domin;
+$data='a7df00100001000000000001013103646e730457434c4d0264650000010001000029057800008000000b00080007000118007541b3';
+$id=substr($data,0,4);
+$flag=substr($data,4,4);
+$questions=substr($data,8,4);
+$answerRRs=substr($data,12,4);
+$authorityRRs=substr($data,16,4);
+$additionalRRs=substr($data,20,4);
+$startbyte=24;
+$dlen=substr($data,$startbyte,2);
+$startbyte=26;
+$i=1;
+while($dlen!='00'){
+$domain[$i]=hex2bin(substr($data,$startbyte,hexdec($dlen)*2));
+$startbyte=$startbyte+(hexdec($dlen)*2);
+$dlen=substr($data,$startbyte,2);
+$startbyte=$startbyte+2;
+$i++;
 }
+$name=join(".",$domain);
+$type=substr($data,$startbyte,4);
+switch($type){
+    case '0001':
+        $type='A';
+        break;
+    case '0002':
+        $type='NS';
+        break;
+    case '000c':
+        $type='PTR';
+        break;
+    case '0006':
+        $type='SOA';
+        break;
+    case '001c':
+        $type='AAAA';
+        break;
+    case '0005':
+        $type='CNAME';
+        break;
+    case '0010':
+        $type='TEXT';
+        break;
+    case '000f':
+        $type='MX';
+        break;                                
 }
-?>
+$query=substr($data,24,$startbyte-20);