diff --git a/utils.inc.php b/utils.inc.php
index ce17408..28ea934 100644
--- a/utils.inc.php
+++ b/utils.inc.php
@@ -11,9 +11,15 @@ function checkDNS($domain, $withWww = false)
     if (empty($currentip)) {
         throw new Exception('the domain '.$domain.' was not found in DNS record.');
     }
+    if (empty($currentip[0]['ip'])) {
+        throw new Exception('the domain '.$domain.' has no ip v4 in DNS record.');
+    }
     if ($currentip[0]['ip'] !== $_SERVER['ip4']) {
         throw new Exception('the current ip v4 address of '.$domain.' is '.$currentip[0]['ip'].'. it should be '.$_SERVER['ip4']);
     }
+    if (empty($currentip[0]['ipv6'])) {
+        throw new Exception('the domain '.$domain.' has no ip v6 in DNS record.');
+    }
     if ($currentip[1]['ipv6'] !== $_SERVER['ip6']) {
         throw new Exception('the current ip v6 address of '.$domain.' is '.$currentip[1]['ipv6'].'. it should be '.$_SERVER['ip6']);
     }