Reverse route injection (RRI) is a method that dynamically installs the network routes for remote tunnel endpoints. The RRI feature allows the router to automatically learn the routes for the remote networks and automatically install these routes into the routing table. This eliminates the need for the administrator to manually configure and maintain the routes for the remote networks. This feature is commonly used in VPN environments, where the router at the VPN endpoint needs to learn the routes for the remote networks behind the other VPN endpoint. The other options such as policy-based routing, CEF, and route filtering are not used to dynamically install the network routes for remote tunnel endpoints