Topology
In this topology R3 is the DR and R1 is the BDR because of the non-preemptive nature of OSPF.
When we run the command “clear ip ospf process” on R1.
As we can see now R4 is the BDR and R3 is the DR.
Explain OSPF DR/BDR Election?
OSPF is a dynamic routing protocol. OSPF can elect one router as DR (Designated Router) and one router as BDR (Backup Designated Router).If DR fails BDR takes over. Each non-BDR or non-DR router in the network exchange routing information with DR or BDR. To send information to DR or BDR multicast IP of 224.0.0.6 is used DR sends routing information with multicast IP of 224.0.0.5.