Node(21) DNS- lookup and resolve

var dns = require('dns');

dns.resolve4('www.google.com', function (err, addresses) {
if (err) throw err;

console.log('addresses: ' + JSON.stringify(addresses));

addresses.forEach(function (a) {
dns.reverse(a, function (err, domains) {
if (err) {
throw err;
}

console.log('reverse for ' + a + ': ' + JSON.stringify(domains));
});
});
});

dns.lookup('google.com', 4, function( e, a ){
console.log(a);
});
// 173.194.43.46