Your network contains an ISA Server 2006 computer named ISA1, which is configured as a remote access VPN server. You configure ISA1 to accept both PPTP and L2TP over IPSec VPN connections from remote access clients. Several users report that they cannot connect to the network. You review the log files on ISA1 and discover that the users with failed connection attempts are all using L2TP over IPSec. You need to ensure that the users can connect to the network. What should you do?

A.
Disable IP fragment blocking.

B.
Disable IP routing.

C.
Disable IP options filtering.

D.
Disable verification of incoming client certificates.