单项选择题
A.lowest root bridge id；lowest sender bridge id；lowest port id；lowest root path cost
B.lowest root path cost；lowest root bridge id；lowest sender bridge id；lowest sender port id
C.lowest root bridge id；lowest sender bridge id；lowest root path cost；lowest sender port id
D.lowest root bridge id；lowest root path cost；lowest sender bridge id；lowest sender port id
问答题 Inarunsparse-dense-modemulticastnetwork，whenrendezvouspointdown，willtherecipientreceivethepacketssendbythesource？why？
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 whatisforward-delay？