Which of the following is NOT an integral part of VPN communication within a network?

A.
VPN key

B.
VPN community

C.
VPN trust entities

D.
VPN domain

Explanation:
VPN key (to not be confused with pre-shared key that is used for authentication).
VPN trust entities, such as a Check Point Internal Certificate Authority (ICA). The ICA is part of the Check
Point suite used for creating SIC trusted connection between Security Gateways, authenticating
administrators and third party servers. The ICA provides certificates for internal Security Gateways and
remote access clients which negotiate the VPN link.
VPN Domain – A group of computers and networks connected to a VPN tunnel by one VPN gateway that
handles encryption and protects the VPN Domain members.
VPN Community – A named collection of VPN domains, each protected by a VPN gateway.

http://sc1.checkpoint.com/documents/R77/CP_R77_VPN_AdminGuide/13868.htm