Question

Four OSPFv2 routers (R1, R2, R3, R4) share a broadcast Ethernet segment in area 0. Their interface priorities are: R1=1, R2=1, R3=0, R4=100. R2 was the first router to boot and became the DR before R4 joined. After R4 came online, an engineer expects R4 to be the DR because of its higher priority, but 'show ip ospf neighbor' still shows R2 as DR and R1 as BDR. R3 shows as DROTHER with FULL/  -  state only to the DR and BDR. Which statement correctly explains the observed behavior?

Accepted Answer

The DR/BDR election is non-preemptive; R4 cannot take over unless the current DR (R2) fails or all OSPF processes on the segment are cleared.

Answer

R4 was excluded from the election because a priority of 100 exceeds the maximum allowed value of 63, so it defaults to DROTHER.

Answer

R3 must become the DR first because a priority of 0 forces it into the election as a tiebreaker, delaying R4's promotion.

Answer

The election will complete correctly within the dead interval once R4's LSAs propagate, and R4 will automatically become DR.