What are two primary requirements?

You have been asked to add a dynamic VPN to your SRX650. This dynamic VPN must be able to support five users at the same time.

What are two primary requirements? (Choose two.)

A.
You must configure IKE to use main mode.

B.
You must configure IKE to use certificates for authentication.

C.
You must configure IKE to use aggressive mode.

D.
You must configure IKE to use preshared keys for authentication.