Which of the following is required to allow placing and receiving URI calls through a firewall?

Which of the following is required to allow placing and receiving URI calls through a firewall?

A.
DNS zones and DNS server should be configured only on the VCS Experssway

B.
Traversal dients behind the firewall should have DNS zones and DNS servers

C.
DID and FindMe must first be configured

D.
DNS records should be configured with the address of the VCS as the authoritative gatekeeper or proxy for the enterprise