Hello Jugal
Let’s take a step back and take a look at DRs and BDRs on any network type.
For a single network segment, OSPF will create adjacencies only between:
- the DR and BDR
- the DR and DROTHER routers
- the BDR and DROTHER routers
There is no adjacency formed between two DROTHER routers. This is the case wherever we see DRs and BDRs regardless of network type. That’s the very purpose of DRs and BDRs, to reduce the number of necessary adjacencies when you have multiple OSPF routers within the same network segment.
Now when it comes to NBMA networks, the only difference is that you must manually choose and define which routers will be DR and BDR using the ip ospf priority command. Typically, if you have a hub and spoke arrangement, the hub should be the DR and there should be no BDR. For more info on this, take a look at the following lesson:
I hope this has been helpful!
Laz