单项选择题
Which IPsec security protocol should be used when confidentiality is required?（）
A. AH B. MD5 C. PSK D. ESP
单项选择题 Which command can you use to manually assign a static IPV6 address to a router interface?（）
单项选择题 Why will a switch never learn a broadcast address?（）
单项选择题 Which parameter can be tuned to affect the selection of a static route as a backup.when a dynamic protocol is also being used?（）
