A. It configures a router to send all packets out interface serial 0/0.
B. It configures a router to block routing updates from being sent out interface serial 0/0.
C. It configures a router as a firewall, blocking all unauthorized packets from exiting serial 0/0.
D. It configures a router to send all packets for unknown destination networks out interface serial 0/0.
E. It configures a router to drop all packets for which the destination network is unknown.
正确答案：参考D
