How does a GDOI-based VPN eliminate the additional tunnel and routing overhead found in DMVPN?

You are designing a multisite VPN solution for a customer and you are concerned with the additional overhead of point-to-point tunnels and the associated overlay routing with DMVPN.

How does a GDOI-based VPN eliminate the additional tunnel and routing overhead found in DMVPN?
A . The GDOI-based VPN requires overlaying a secondary routing infrastructure through the tunnels.
B . In a GDOI-based VPN, all group members share a common security association.
C . The GDOI-based VPN requires the provisioning of a complex connectivity mesh.
D . The GDOI-based VPN leverages the routing protocol to find its peer for tunnel setup.

Answer: B