PHP DNS ホスト名から名前解決をする方法

<?php
$info = dns_get_record ('www.google.co.jp', DNS_A);
print_r($info);
?>

Array
(
    [0] => Array
        (
            [host] => www.l.google.com
            [type] => A
            [ip] => 66.249.89.99
            [class] => IN
            [ttl] => 294
        )

    [1] => Array
        (
            [host] => www.l.google.com
            [type] => A
            [ip] => 66.249.89.104
            [class] => IN
            [ttl] => 294
        )

    [2] => Array
        (
            [host] => www.l.google.com
            [type] => A
            [ip] => 66.249.89.147
            [class] => IN
            [ttl] => 294
        )

)