多项选择题 Router R1 sits at an Enterprise branch office, using both the Internet and a leased line to another Enterprise router for its two connectivity options back into the rest of the Enterprise network. The engineer planning for this branch decided to use the leased line for all Enterprise traffic, unless it fails, in which case the Internet connection should be used to pass traffic to the Enterprise. Which of the following is most likely to be useful on the branch router?（）

单项选择题 Router R1 sits at an Enterprise branch office, using the Internet for its only connectivity back to the rest of the EnterprisE. Which of the following is not a ben efit of using an IPsec tunnel for packets sent through the Internet, between R1 and the rest of the Enterprise?（）

单项选择题 Router R1 use s MAC address 1111.1111.1111 for its Fa0/0 interface. An engineer sees the following configuration in the output of a show running - config command. Then, the engineer issues a show ipv6 interface brief command. What global unicast IPv6 address does this c ommand display for interface tunnel 1?（） interface loopback 1 ip address 192.168.1.1 255.255.255.255 interface tunnel 1 tunnel source loopback 1 tunnel destination 192.168.1.2 tunnel mode ipv6ip isatap ipv6 address 2000::/64 eui - 64