Which Cisco VPN technology can use multipoint tunnel, resulting in a single GRE tunnel interface on the hub, to support multiple connections from multiple spoke devices?

DMVPN (Dynamic Multipoint VPN) leverages mGRE (multipoint GRE) tunnels, allowing a single GRE interface on the hub router to serve multiple spoke routers simultaneously. This design significantly simplifies hub configuration and enables dynamic spoke-to-spoke tunnel establishment for optimal data paths.

GETVPN (Group Encrypted Transport VPN) is primarily designed for 'any-to-any' secure communication within a single autonomous system, focusing on encrypting existing routing topologies rather than dynamic multipoint tunnels at the hub.

Cisco Easy VPN simplifies the deployment and management of IPsec VPNs, typically for remote access clients or small branch offices, but it does not inherently provide the multipoint hub functionality of DMVPN.

FlexVPN is a unified framework that can integrate various VPN technologies, including DMVPN-like functionality, but DMVPN itself is the specific technology characterized by a single mGRE tunnel interface on the hub.