多项选择题 WhichtwoofthesestatementscorrectlydescribeclassicPIM-SM？（）

单项选择题 Refer to the exhibit. In this network， R1 has been configured to advertise a summary route， 192.168.0.0/22， to R2. R2 has been configured to advertise a summary route， 192.168.0.0/21， to R1. Both routers have been configured to remove the discard route （the route to null created when a summary route is configured） by setting the administrative distance of the discard route to 255.What will happen if R1 receives a packet destined to 192.168.3.1？（）

问答题 ARP和反向ARP啥意思？