Refer to the exhibit.
You have completed an OSPF implementation, and you are verifying OSPF
operation. You notice that router A and router B are stuck in the two-way state. From the show ip
ospf interface command output, what is the cause of this issue?
A.
All OSPF implementations must have at least one interface in area 0.
B.
You are attempting to run in the broadcast mode over an NBMA interface.
C.
Both routers are configured to function as a BDR; therefore, there is no DR router.
D.
Someone has changed the OSPF router ID; therefore you must clear the OSPF process.
E.
The OSPF priority is set to 0 on both routers; therefore neither can become the DR.
Explanation:
When OSPF adjacency is formed, a router goes through several state changes before it becomes
fully adjacent with its neighbor. The states are Down, Attempt, Init, 2-Way, Exstart, Exchange,
Loading, and Full.
An OSPF neighbor reaches the 2-way state when bidirectional communication is established
(each router has seen the other’s hello packet). This is the beginning of an OSPF adjacency. On
broadcast media and non-broadcast multiaccess networks, the DR and BDR are elected in this
state. But the priority on both routers are 0 so no DR and BDR are elected -> These routers stay in
the 2-way state.
(Reference and a good resource of OSPF Neighbor states:
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f0e.shtml)