protected function _getDefaultBackend() {
        $timeout = Mage::getStoreConfig('turpentine_vcl/backend/frontend_timeout');
        $default_options = array(
            'first_byte_timeout'    => $timeout.'s',
            'between_bytes_timeout' => $timeout.'s',
        );
        if (Mage::getStoreConfig('turpentine_vcl/backend/load_balancing') != 'no') {
            return $this->_vcl_director('default', $default_options);
        } else {
            return $this->_vcl_backend('default',
                Mage::getStoreConfig('turpentine_vcl/backend/backend_host'),
                Mage::getStoreConfig('turpentine_vcl/backend/backend_port'),
                $default_options);
        }
    }