Refer to the exhibit.
The network administrator is adding a new spoke, but the tunnel is not passing traffic. What
could cause this issue?
A.
DMVPN is a point-to-point tunnel, so there can be only one spoke.
B.
There is no EIGRP configuration, and therefore the second tunnel is not working.
C.
The NHRP authentication is failing.
D.
The transform set must be in transport mode, which is a requirement for DMVPN.
E.
The NHRP network ID is incorrect.
I think that even Network-ID incorrect
C
This is confusing because network-id is not matching on both routers, but its not needed to match to set up the nhrp process, as explained here http://www.cisco.com/c/en/us/td/docs/ios/12_4/ip_addr/configuration/guide/hadnhrp.html#wp1055049
ip nhrp authentication, is not matching con both routers, but this is the key for nhrp to register spokes with the hub. So the answer is C.
The NHRP network ID is a local only parameter. It is significant only to the local router and it is not transmitted in NHRP packets to other NHRP nodes. For this reason the actual value of the NHRP network ID configured on a router need not match the same NHRP network ID on another router where both of these routers are in the same NHRP domain. As NHRP packets arrive on a GRE interface, they are assigned to the local NHRP domain in the NHRP network ID that is configured on that interface.
The authentication in both router must be the same string. As we can see in Hub is “DMVPN01” and in the spoke is “DMVPN1”.
So The answear is C.