单项选择题 An engineer is reviewing another engineers sample configuration for a GRE tunnel used to pass IPv6 traffiC. The tunnel ha s not yet been configured on the router. Which of the following commands is not required for the configuration to pass IPv6 traffic?（）

单项选择题 The following configura tion exists on a router on one end of an IPv6 tunnel. Which type of tunnel is created by this configuration?（） interface loopback 1 ip address 1.1.1.1 255.255.255.255 interface tunnel 2 ipv6 address 2000::1::/64 tunnel source loopback 1 tunnel destina tion 2.2.2.2 tunnel mode ipv6ip ipv6 eigrp 1

单项选择题 A client host uses IPv4 to communicate with one ser ver and IPv6 to communicate with another.Which of the following IPv6 coexistence features is likely at work on the host?（）