Which component performs the resolution between the tunnel address and mGRE address in DMVPN?

GDOI (Group Domain of Interpretation) is a key management protocol used in Group Encrypted Transport VPN (GET VPN) and is not involved in address resolution for DMVPN.

NBMA (Non-Broadcast Multi-Access) refers to the underlying network type (like the internet) over which DMVPN operates, and while mGRE addresses are NBMA addresses, NBMA itself is not a resolution protocol.

The Next Hop Resolution Protocol (NHRP) is the core protocol in DMVPN that performs the resolution between a router's private tunnel IP address and its corresponding public mGRE (Non-Broadcast Multi-Access) address, allowing spokes to dynamically find each other.

NHS (Next Hop Server) is a functional role within NHRP, typically played by the DMVPN hub, which maintains the NHRP mapping database, but NHRP is the protocol performing the resolution, not NHS itself.