protected function compareDnsRecords($original, $new)
    {
        $differences['original'] = $original;
        $differences['new'] = $new;

        foreach ($original as $original_id => $original_record) {
            foreach ($new as $new_id => $new_record) {
                if ($original_record == $new_record) {
                    unset($differences['original'][$original_id]);
                    unset($differences['new'][$new_id]);
                }
            }
        }

        return $differences;
    }