Configure and verify single-area OSPFv2, including neighbor adjacencies, point-to-point and broadcast (DR/BDR) network types, and the router ID

Configure and verify single-area OSPFv2, including neighbor adjacencies, point-to-point and broadcast (DR/BDR) network types, and the router ID.

Bring up OSPFv2 neighbours by matching area, subnet, hello and dead timers, and authentication, and recognise the states an adjacency passes through to FULL. Distinguish point-to-point links, which form a direct adjacency, from broadcast segments, which elect a designated router and backup DR by highest OSPF priority then highest router ID, and confirm how the router ID is chosen when not set manually.

OSPFv2 single areaNeighbor adjacencyDR/BDR electionOSPF router IDOSPF network types

Practice question for this objective

Free sampleIP Connectivityhard

R1 and R2 connect over a serial link configured as an OSPF point-to-point network. R1 forms a full adjacency on its LAN but the serial neighbour stays in INIT. The following output is from R1: R1# show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.0.0.2 0 INIT/ - 00:00:38 10.0.0.2 Serial0/0/0 R1# show ip ospf interface Serial0/0/0 Timer intervals: Hello 10, Dead 40, Wait 40, Retransmit 5 Area 0, Network type POINT_TO_POINT R2# show ip ospf interface Serial0/0/0 Timer intervals: Hello 30, Dead 120, Wait 120, Retransmit 5 Area 0, Network type POINT_TO_POINT What is the most likely cause?

R1# show ip ospf interface serial0/0/0
Serial0/0/0 is up, line protocol is up
  Internet Address 10.1.12.1/30, Area 0
  Network Type POINT_TO_POINT
  Timer intervals configured, Hello 10, Dead 40
R2# show ip ospf interface serial0/0/0
  Internet Address 10.1.12.2/30, Area 0
  Network Type POINT_TO_POINT
  Timer intervals configured, Hello 30, Dead 120

ANo DR has been elected on the point-to-point link, so the neighbours cannot reach FULL
BThe two interfaces are in different OSPF areas, preventing the adjacency from forming
CThe /30 subnet provides too few host addresses to support two OSPF neighbours
DThe hello and dead timers differ between R1 and R2, so the adjacency cannot progress past INIT Correct

OSPF neighbours must share matching hello and dead timers; a mismatch holds the adjacency in INIT and prevents it reaching FULL. For OSPF to form an adjacency the hello and dead intervals must match on both ends. R1 advertises Hello 10 / Dead 40 and R2 advertises Hello 30 / Dead 120, so the hello packets are rejected and the state cannot advance beyond INIT; point-to-point links elect no DR, and the areas and /30 sizing are already correct.

Why A is wrong: Point-to-point links never elect a DR or BDR, so a missing DR cannot be the cause; this misapplies broadcast behaviour to the wrong network type.

Why B is wrong: Both interfaces show Area 0, so the area values already match; an area mismatch would be a valid blocker in general but is not what the output shows here.

Why C is wrong: A /30 yields two usable hosts, exactly enough for a point-to-point pair, so address count is not the issue and this reasoning is incorrect.

Why D is correct: R1 uses Hello 10 / Dead 40 while R2 uses Hello 30 / Dead 120; mismatched timers stop the neighbours agreeing, leaving the state stuck and matching the INIT symptom exactly.

See more 200-301 practice questions, answers explained.

Examworthy is not affiliated with or endorsed by Cisco. Original, blueprint-aligned practice material only.

Configure and verify single-area OSPFv2, including neighbor adjacencies, point-to-point and broadcast (DR/BDR) network types, and the router ID.

Practice question for this objective

More in this domain