In a new DMVPN deployment, phase 1 completes successfully. However, phase2 experiences issues. Which troubleshooting step is valid in this situation?
A. Temporarily remove encryption to check if the GRE tunnel is working.
B. Verify IP routing between the external IPs of the two peers is correct.
C. Remove NHRP configuration and reset the tunnels.
D. Ensure that the nodes use the same authentication method.
