Your network contains an ISA Server 2006 computer named ISA1, which allows outgoing connections to the Internet. A network rule defines a network address translation (NAT) relationship between the Internal network and the Internet. Users on ISA Server protected networks require access to PPTP and L2TP over IPSec VPN servers on the Internet. You configure all network computers, except ISA1, as both Web Proxy and Firewall clients. You create access rules on ISA1 to allow outbound connections to the Internet by using PPTP Client,
IPSec NAT Traversal (NAT-T) Client, and IKE Client protocols. You discover that users cannot connect to Internet PPTP and L2TP over IPSec VPN servers. You need to ensure that users can connect to PPTP and L2TP over IPSec VPN servers on the Internet. What should you do?

A.
Disable the Web Proxy client configuration on the network computers.

B.
Disable the Firewall client configuration on the network computers.

C.
Configure the network computers as SecureNAT clients.

D.
Configure the network computers to use IPSec tunnel mode.