單項選擇題
Refer to the exhibit.S0/0 on R1 is configured as a multipoint interface to communicate with R2 and R3 in the hub-and-spoke Frame Relay topology. While testing this configuration， a technician notes that pings are successfully from hosts on the 172.16.1.0/24 network to hosts on both the 172.16.2.0/25 and 172.16.0.2.128/25 networks. However， pings between hosts on the 172.16.2.0/25 and 172.16.2.128/25 network are not successful. What could explain this connectivity problem？（）
A.The ip subnet-zero command has been issued on the R1 router.
B.The RIPv2 dynamic routing protocol cannot be used across a Frame Relay network.
C.Split horizon is preventing R2 from learning about the R3 networks and R3 from learning about R2 networks.
D.The 172.16.2.0/25 and 172.16.2.128/25 networks are overlapping networks that can be seen by R1,but not between R2 and R3.
E.The 172.16.3.0/29 network used on the Frame Relay links is creating a discontiguous network between the R2 and R3 router subnetworks.
