单项选择题 Refer to the exhibit. Router E learned about the PIM RP （designated as 7.7.7.7） from four different sources. Routers A and D advertised the 7.0.0.0 network via EIGRP. Routers B and C advertised the 7.0.0.0 network via OSPF. Considering that all four Ethernet interfaces on router E could potentially lead back to the PIM-RP， when router E receives the first multicast packet down the shared tree， which incoming interface will be used to successfully pass the RPF check？（）

单项选择题 On the basis of the network provided in the exhibit， all routers are configured to run EIGRP on all links. If the link between PG-R1 and PG-R2 fails， what is the maximum number of queries PG-R3 will receive for 192.168.1.0/24， assuming that all the packets sent during convergence are transmitted once （there are no dropped or retransmitted packets）？（）

问答题 缓解一个网络的不同的子网的地址空间不足的方法是什么？