Last Updated on November 23, 2020 by Admin
Refer to the exhibit. Which conclusion can be drawn from this OSPF multiaccess network?
CCNA3 v7 – ENSA Final Exam Answers 21
- All DROTHER routers will send LSAs to the DR and BDR to multicast 224.0.0.5.
- When a DR is elected all other non-DR routers become DROTHER.
- If the DR stops producing Hello packets, a BDR will be elected, and then it promotes itself to assume the role of DR.
- With an election of the DR, the number of adjacencies is reduced from 6 to 3.
Answers Explanation & Hints: On OSPF multiaccess networks, a DR is elected to be the collection and distribution point for LSAs sent and received. A BDR is also elected in case the DR fails. All other non-DR or BDR routers become DROTHER. Instead of flooding LSAs to all routers in the network, DROTHERs only send their LSAs to the DR and BDR using the multicast address 224.0.0.6. If there is no DR/BDR election, the number of required adjacencies is n(n-1)/2 = > 4(4-1)/2 = 6. With the election, this number is reduced to 3.