单项选择题 Which command will need to be added to External_A to ensure that it will take over if serial 0/0 on  External_B fails？ （）

单项选择题 You want to allow Router R1 to immediately become the active router if its priority is highest than  the active router fails.  What command would you use if you wanted to configure this？ （）

多项选择题 WhatthreetasksmustanetworkadministratorperformtoproperlyconfigureHotStandbyRoutingProtocol（HSRP）？（）