单项选择题
A. The interface used to connect to that neighbor being passive in the OSPF process
B. Duplicate OSPF router IDs
C. Mismatched dead timers
D. IP addr esses of 10.1.1.1/24 and 10.2.2.2/24
E. Mismatched OSPF process IDs
多项选择题 Routers R1 and R2, OSPF neighbors in area 0 over their Fa0/0 interfaces (respectively), currently both successfully use OSPF MD5 authentication. The OSPF configuration includes the area 0 authentication command under the router ospf 1 command. Which of the following commands must have been configur ed on R1s Fa0/0 interface?（）
多项选择题 Routers R1 and R2 are OSPF neighbors using their Fa0/0 interfaces, respectively, using default settings for all timers. An engineer ad ds the ip ospf hello - interval 6 command to R1s Fa0/0 configuration. Which of the following is true regarding the results from this change?（）
多项选择题 Rout er R1 directly connects to subnet 10.1.1.0/24 with its Fa0/0 interface. R1 can ping four other working OSPF routers in that subnet. R1 is neither the designated router (DR) nor backup DR (BDR). OSPF is working correctly on all five routers. Which of the following is true on R1?（）