This 200-301 practice question tests your understanding of connected to r1 via console. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
R1#show running-config | section router ospf router ospf 1 router-id 1.1.1.1 log-adjacency-changes network 10.0.0.0 0.0.0.3 area 0 network 10.0.0.4 0.0.0.3 area 0 passive-interface default passive-interface GigabitEthernet0/0 passive-interface GigabitEthernet0/1 ! R1#show ip ospf neighbor R1#show ip interface brief | exclude unassigned Interface IP-Address OK? Method Status Protocol GigabitEthernet0/0 10.0.0.1 YES manual up up GigabitEthernet0/1 10.0.0.5 YES manual up up R2#show running-config | section router ospf router ospf 1 router-id 2.2.2.2 log-adjacency-changes network 10.0.0.0 0.0.0.3 area 0 network 10.0.0.8 0.0.0.3 area 0 ! R3#show running-config | section router ospf router ospf 1 router-id 3.3.3.3 log-adjacency-changes network 10.0.0.4 0.0.0.3 area 0 network 10.0.0.8 0.0.0.3 area 0 ! Topology: R1 G0/0 (10.0.0.1/30) --- linkA (10.0.0.0/30) --- R2 G0/0 (10.0.0.2/30) R1 G0/1 (10.0.0.5/30) --- linkB (10.0.0.4/30) --- R3 G0/0 (10.0.0.6/30) R2 G0/1 (10.0.0.9/30) --- linkC (10.0.0.8/30) --- R3 G0/1 (10.0.0.10/30)
You are connected to R1 via console. The network administrator has attempted to configure OSPFv2 between R1, R2, and R3 but OSPF neighbor adjacencies are failing. Configure R1 to correct all issues so that R1 becomes FULL neighbors with both R2 and R3. Do not modify any other device's configuration.
Correct answer & explanation
The issue is that R1 has 'passive-interface default' and then explicitly configured both GigabitEthernet0/0 and GigabitEthernet0/1 as passive, which prevents OSPF hello packets from being sent on those interfaces. Since OSPF requires hello messages to form and maintain neighbor relationships, no neighbors are seen. The fix is to remove the passive-interface statements for the interfaces that connect to OSPF neighbors and also ensure that the 'passive-interface default' is either removed or overridden with 'no passive-interface' for those interfaces. Additionally, the network statements on R1 are correct for the connected subnets, so no changes are needed there.
Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Common exam traps
OSPF neighbour formation depends on matching areas, timers, network type, authentication and passive-interface behaviour. Do not choose an answer only because the devices can ping.
Detailed technical explanation
OSPF questions usually test the details that control adjacency and route selection. Read the neighbour state, area, router ID and interface configuration before deciding what is wrong.
Key takeaway
OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Real-world example
A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
What to study next
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 200-301 OSPF questions on adjacency and route selection.
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Practice this exam
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FAQ
OSPF neighbours must agree on key parameters.
Common exam trap: OSPF can fail even when IP connectivity looks correct: OSPF neighbour formation depends on matching areas, timers, network type, authentication and passive-interface behaviour. Do not choose an answer only because the devices can ping.
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 200-301 OSPF questions on adjacency and route selection.
OSPF neighbours must agree on key parameters.
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