多项选择题
A. The show ip ospf neighbor command on R1 lists the revised Hello timer
B. The show ip ospf interfac e brief command on R1 lists the revised Hello timer
C. The R1 - R2 neighborship fails due to Hello timer mismatcH
D. The show ip ospf interface command on R1 lists the revised Hello timer
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?（）
多项选择题 Which of the following can either directly or indirec tly identify all the interfaces for which both 1) OSPF has been enabled and 2) OSPF is not passive?（）
单项选择题 Which of the following is true about an OSPF area border router (ABR)?（）