What is a potential problem with using GETVPN for this design solution?

Your organization is working on a design solution for a new Internet-based remote access virtual private network that has 1000 remote sites. A network administrator recommends GETVPN as the model because the network of today uses DMVPN, which results in a lot of background NHRP control traffic.

What is a potential problem with using GETVPN for this design solution?
A . GETVPN would require a high level of background traffic to maintain its IPsec SAs.
B . GETVPN is not scalable to a large number of remote sites.
C . GETVPN and DMVPN will not interoperate.
D . GETVPN key servers would be on public, hacker-reachable space and need higher security.

Answer: D