Which DMVPN feature allows spokes to be deployed with dynamically assigned public IP addresses?

2547oDMVPN integrates MPLS Layer 3 VPN functionality over a DMVPN underlay for carrying VPN routing information; it has no role in resolving or registering dynamic spoke addresses.

NHRP acts as a dynamic address-resolution database in DMVPN: each spoke sends a registration message to the hub (Next Hop Server) containing its current NBMA (public) IP address when the tunnel comes up. This registration process means the hub always knows where to route traffic for each spoke regardless of whether the spoke's public IP changes, which is the fundamental mechanism that allows dynamic IP addressing in DMVPN deployments.

OSPF is a routing protocol used to exchange prefix reachability information over the DMVPN tunnels but has no mechanism to handle the mapping between tunnel addresses and dynamic physical IP addresses.

NAT Traversal (NAT-T) encapsulates IKE and ESP inside UDP port 4500 to allow VPN traffic to pass through NAT devices; it addresses address translation at NAT boundaries but does not provide dynamic IP registration for spokes.