You observe that a router is using an unusually high amount of CPU cycles. You determine that
continuous SPF calculations in OSPF are being performed.
What are two reasons for this problem? (Choose two.)

A.
The wrong authentication keys between the OSPF neighbors are used.

B.
The interface MTU is mismatched between the OSPF neighbors.

C.
There are duplicate router IDs within the OSPF area.

D.
An OSPF adjacency is flapping.

Explanation: