A: "It requires the use of dynamic routing protocols so that spokes can learn the routes to other spokes." This statement is accurate. Auto Discovery VPN (ADVPN) often works in conjunction with dynamic routing protocols to allow spokes to dynamically learn routes to other spokes. This dynamic routing capability enhances the scalability and flexibility of the VPN.
C: "Tunnels are negotiated dynamically between spokes."
This statement is also accurate. In ADVPN, the tunnels between spokes are negotiated dynamically, meaning the VPN connections are established on-demand without requiring manual configuration for each potential spoke.
Therefore, both statements A and C are correct, and they provide a comprehensive view of Auto Discovery VPN (ADVPN) functionalities.