The answer is to configure `ip ospf hello-interval 5` and `ip ospf dead-interval 20` under R1’s GigabitEthernet0/0 interface. This is correct because an OSPF adjacency stuck in EXSTART state is almost always caused by a timer mismatch—OSPF requires that both the hello and dead intervals match exactly between neighbors before they can exchange Database Description packets and move past EXSTART. On the CCNA 200-301 v2 exam, this scenario tests your ability to recognize that mismatched timers prevent the neighbor state from progressing beyond EXSTART, even when other OSPF parameters like area and network type are correct. A common trap is assuming the issue is an MTU mismatch or a passive interface, but the dead giveaway here is that R2’s timers (5/20) differ from R1’s defaults (10/40). To verify, use `show ip ospf neighbor` to confirm the state changes to FULL after the fix. Memory tip: “EXSTART means timers are apart—match the hello and dead to get ahead.”
CCNA IP Routing Practice Question
This 200-301 practice question tests your understanding of ip routing. 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.
Network Topology
You are connected to R1. Configure OSPFv2 on R1 and R2 so that they form a full adjacency and can exchange routes. Currently, the adjacency is stuck in EXSTART state. Identify and fix the issue, then verify the adjacency becomes FULL.
R1#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
172.16.1.2 1 EXSTART/DR 00:00:30 10.0.0.2 GigabitEthernet0/0
R1#show running-config | section interface GigabitEthernet0/0
interface GigabitEthernet0/0
ip address 10.0.0.1 255.255.255.252
ip ospf hello-interval 10
ip ospf dead-interval 40
duplex auto
speed auto
media-type rj45
!
R1#show running-config | section router ospf
router ospf 1
router-id 1.1.1.1
network 10.0.0.0 0.0.0.3 area 0
!
R2#show running-config | section interface GigabitEthernet0/0
interface GigabitEthernet0/0
ip address 10.0.0.2 255.255.255.252
ip ospf hello-interval 5
ip ospf dead-interval 20
duplex auto
speed auto
media-type rj45
!
R2#show running-config | section router ospf
router ospf 1
router-id 172.16.1.2
network 10.0.0.0 0.0.0.3 area 0
!
A
On R1, configure 'ip ospf hello-interval 5' and 'ip ospf dead-interval 20' under interface GigabitEthernet0/0.
This is correct because OSPF requires matching hello and dead intervals on both routers to form a full adjacency. R2 has hello 5 and dead 20, so adjusting R1 to match resolves the EXSTART state.
B
On R1, configure 'ip ospf network point-to-point' under interface GigabitEthernet0/0.
Why wrong: This is incorrect because changing the network type does not address the timer mismatch causing the EXSTART state. While network type must match, the primary issue here is timer mismatch.
C
On R2, configure 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40' under interface GigabitEthernet0/0.
Why wrong: This is incorrect because while it would also fix the mismatch, the question asks to fix the issue on R1, not R2. The scenario implies R1 is the router you are connected to, so changes should be made on R1.
D
On R1, configure 'ip ospf dead-interval 40' under interface GigabitEthernet0/0.
Why wrong: This is incorrect because only adjusting the dead interval does not resolve the mismatch; the hello interval must also match. OSPF requires both timers to be consistent.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
On R1, configure 'ip ospf hello-interval 5' and 'ip ospf dead-interval 20' under interface GigabitEthernet0/0.
The adjacency is stuck in EXSTART because the OSPF hello and dead timers are mismatched between R1 and R2. R1 has hello-interval 10 and dead-interval 40, while R2 has hello-interval 5 and dead-interval 20. OSPF requires these timers to match for adjacency formation. To fix this, adjust the timers on R1 to match R2 (or vice versa). On R1, configure 'ip ospf hello-interval 5' and 'ip ospf dead-interval 20' under interface GigabitEthernet0/0. After correction, the adjacency should progress to FULL.
Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
On R1, configure 'ip ospf hello-interval 5' and 'ip ospf dead-interval 20' under interface GigabitEthernet0/0.
Why this is correct
This is correct because OSPF requires matching hello and dead intervals on both routers to form a full adjacency. R2 has hello 5 and dead 20, so adjusting R1 to match resolves the EXSTART state.
On R1, configure 'ip ospf network point-to-point' under interface GigabitEthernet0/0.
Why it's wrong here
This is incorrect because changing the network type does not address the timer mismatch causing the EXSTART state. While network type must match, the primary issue here is timer mismatch.
✗
On R2, configure 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40' under interface GigabitEthernet0/0.
Why it's wrong here
This is incorrect because while it would also fix the mismatch, the question asks to fix the issue on R1, not R2. The scenario implies R1 is the router you are connected to, so changes should be made on R1.
✗
On R1, configure 'ip ospf dead-interval 40' under interface GigabitEthernet0/0.
Why it's wrong here
This is incorrect because only adjusting the dead interval does not resolve the mismatch; the hello interval must also match. OSPF requires both timers to be consistent.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓On R1, configure 'ip ospf hello-interval 5' and 'ip ospf dead-interval 20' under interface GigabitEthernet0/0.Correct answer▾
Why this is correct
This is correct because OSPF requires matching hello and dead intervals on both routers to form a full adjacency. R2 has hello 5 and dead 20, so adjusting R1 to match resolves the EXSTART state.
✗On R1, configure 'ip ospf network point-to-point' under interface GigabitEthernet0/0.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the adjacency is stuck due to timer mismatch, not network type mismatch.
Why candidates choose this
Candidates pick this because they know network type must match for OSPF adjacency, but they overlook the timer mismatch as the root cause.
✗On R2, configure 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40' under interface GigabitEthernet0/0.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the configuration should be applied to R1, not R2, as per the question context.
Why candidates choose this
Candidates pick this because they correctly identify the timer mismatch but fail to note that the question specifies configuring on R1.
✗On R1, configure 'ip ospf dead-interval 40' under interface GigabitEthernet0/0.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that both hello and dead intervals must match; changing only one leaves a mismatch.
Why candidates choose this
Candidates pick this because they think the dead interval is the only critical timer, but OSPF checks both hello and dead intervals.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
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.
Trap categories for this question
Scenario analysis trap
This is incorrect because while it would also fix the mismatch, the question asks to fix the issue on R1, not R2. The scenario implies R1 is the router you are connected to, so changes should be made on R1.
Detailed technical explanation
How to think about this question
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.
KKey Concepts to Remember
OSPF neighbours must agree on key parameters.
Router ID selection can affect neighbour relationships and LSDB output.
OSPF cost influences the preferred path.
A route can appear in OSPF information but not become the installed route.
TExam Day Tips
→Check area mismatch first when OSPF adjacency fails.
→Review passive interfaces when a network is advertised but no neighbour forms.
→Use show ip ospf neighbor and show ip route clues carefully.
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
How this comes up in practice
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
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.
IP Routing — This question tests IP Routing — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: On R1, configure 'ip ospf hello-interval 5' and 'ip ospf dead-interval 20' under interface GigabitEthernet0/0. — The adjacency is stuck in EXSTART because the OSPF hello and dead timers are mismatched between R1 and R2. R1 has hello-interval 10 and dead-interval 40, while R2 has hello-interval 5 and dead-interval 20. OSPF requires these timers to match for adjacency formation. To fix this, adjust the timers on R1 to match R2 (or vice versa). On R1, configure 'ip ospf hello-interval 5' and 'ip ospf dead-interval 20' under interface GigabitEthernet0/0. After correction, the adjacency should progress to FULL.
What should I do if I get this 200-301 question wrong?
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.
What is the key concept behind this question?
OSPF neighbours must agree on key parameters.
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