单项选择题
A. The primary router R1 will reassume the active role when it comes back online.
B. The standby router R2 will remain active and will forward the active role to router R1 only in the event of its own failure.
C. The standby router R2 will remain active and will forward the active role to router R1 only in the event of Link B failure.
D. The third member of the HSRP group， router R3， will take over the active role only in event of router R2 failure.
单项选择题 Refer to the exhibit. The Gateway Load Balancing Protocol has been configured on routers R1 and R2， and hosts A and B have been configured as shown. Which statement can be derived from the exhibit？（）
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？（）
多项选择题 Routers can send hello messages in three HSRP states. Which ones are they？（）
