单项选择题 Which configuration will enable OSPF for IPv6 on FastEthernet 0/0/0?（）

单项选择题 In a high-availability network, which command, when placed on ports that have connected end stations, will allow you to prevent delays in service for end stations by placing a port in blocking mode?（）

多项选择题 In a RSTP implementation, which of the following two link types are used? （）(Choose two.)