Whether the elected DR and BDR in a broadcast network listen to both the 224.0.0.5 address and the 224.0.0.6 address

Question

Options

• ATRUE
• BFALSE

• A
  85% (33)
• B
  15% (6)

Explanation

Option A is correct because in OSPF broadcast networks, the DR and BDR must listen on both multicast addresses: 224.0.0.5 (AllSPFRouters) because they are OSPF routers themselves, and 224.0.0.6 (AllDRouters) because they hold the DR/BDR role and must receive LSU/LSAck packets sent directly to them by DROther routers. Option B is incorrect because it would imply DR/BDR only listen on one address, ignoring that their special role requires them to hear traffic destined specifically for DRs. DROther routers, by contrast, only subscribe to 224.0.0.5 - they never join 224.0.0.6 - which is what makes this question a common trap.

Memory tip: Think of the DR/BDR as having two jobs - being a regular OSPF router (.5) AND being the neighborhood manager (.6). Two jobs = two addresses. DROthers only have one job, so they only need one address.

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