Fix dns_uv.lookup order

lib/dns_uv.js

@@ -142,7 +142,23 @@ exports.lookup = function(domain, family, callback) {
     }
   }
 
-  var wrap = cares.getHostByName(domain, familyToSym(family), onanswer);
+  var wrap;
+
+  if (family) {
+    // resolve names for explicit address family
+    var af = familyToSym(family);
+    wrap = cares.getHostByName(domain, af, onanswer);
+  } else {
+    // first resolve names for v4 and if that fails, try v6
+    wrap = cares.getHostByName(domain, cares.AF_INET, function(err, domains4) {
+      if (domains4 && domains4.length) {
+        callback(null, domains4[0], 4);
+      } else {
+        cares.getHostByName(domain, cares.AF_INET6, onanswer);
+      }
+    });
+  }
+
   if (!wrap) {
     throw errnoException(errno, 'getHostByName');
   }