Braintree\Configuration::serverName PHP Method

    public function serverName()
    {
        switch ($this->_environment) {
            case 'production':
                $serverName = 'api.braintreegateway.com';
                break;
            case 'qa':
                $serverName = 'gateway.qa.braintreepayments.com';
                break;
            case 'sandbox':
                $serverName = 'api.sandbox.braintreegateway.com';
                break;
            case 'development':
            case 'integration':
            default:
                $serverName = 'localhost';
                break;
        }
        return $serverName;
    }