In the OSPF routing domain, in broadcast networks and NBMA networks containing at least two routers, one router must be designated as the DR and the other as the BDR.

Question

Options

• ATRUE
• BFALSE

• A
  29% (7)
• B
  71% (17)

Explanation

Option B (FALSE) is correct because while a DR is always elected in broadcast and NBMA networks with multiple routers, a BDR is not guaranteed. If a router's OSPF interface priority is set to 0, it becomes ineligible for DR/BDR election - so in a two-router scenario where one has priority 0, a DR is elected but no BDR exists.

Option A (TRUE) is incorrect because it assumes both roles are always filled, overlooking the case where router priority settings can prevent a BDR from being elected. The OSPF spec requires a DR, but the BDR is only elected when there are at least two eligible candidates (priority > 0).

Memory tip: Think "DR = mandatory, BDR = maybe." A priority of 0 means "I refuse to lead" - that router won't become DR or BDR, which can leave a network with a DR but no BDR backup.

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