Chapter 11 IPsec VPN for FortiOS 5.0 : Dynamic DNS configuration : Dynamic DNS over VPN concepts : Dynamic DNS over VPN : Route-based or policy-based VPN
  
Route-based or policy-based VPN
VPN over dynamic DNS can be configured with either route-based or policy-based VPN settings. Both are valid, but have differences in configuration. Choose the best method based on your requirements. For more information on route-based and policy-based, see “Types of VPNs”.
Route-based VPN configuration requires two security policies to be configured (one for each direction of traffic) to permit traffic over the VPN virtual interface, and you must also add a static route entry for that VPN interface or the VPN traffic will not reach its destination. See “Creating branch_2 route-based security policies” and “Creating branch_1 route-based security policies”.
Policy-based VPN configuration uses more complex and often more IPsec security policies, but does not require a static route entry. It has the benefit of being able to configure multiple policies for handling multiple protocols in different ways, such as more scanning of less secure protocols or guaranteeing a minimum bandwidth for protocols such as VoIP. See “Creating branch_2 policy-based security policies” and “Creating branch_1 policy-based security policies”