CCNA IP Routing Practice Question
Network Topology
You are connected to R1. Configure OSPFv2 on R1 and R2 so that they form a full adjacency and can exchange routes. The current configuration has mismatched hello/dead timers blocking the adjacency. Adjust only the necessary settings on R1 to match R2's OSPF timers.
⚠ Common exam trap
A common trap is assuming that changing only the hello interval will automatically adjust the dead interval, or vice versa. In Cisco IOS, these timers are independent and must be set explicitly. Also, note that the dead interval must be at least four times the hello interval, but that relationship is not enforced automatically.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Configure 'ip ospf hello-interval 5' and 'ip ospf dead-interval 20' on R1's GigabitEthernet0/0 interface.
The adjacency between R1 and R2 is not forming because the OSPF hello and dead timers are mismatched. R1 has default timers (Hello 10, Dead 40) while R2 has custom timers (Hello 5, Dead 20). To form an adjacency, OSPF timers must match on both ends. On R1, you need to configure the OSPF interface timers to match R2 by issuing 'ip ospf hello-interval 5' and 'ip ospf dead-interval 20' on interface GigabitEthernet0/0. After applying these commands, the adjacency should come up.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Configure 'ip ospf hello-interval 5' and 'ip ospf dead-interval 20' on R1's GigabitEthernet0/0 interface.
Why this is correct
This is correct because OSPF requires matching hello and dead timers on both routers for adjacency formation. R2 uses hello 5 and dead 20, so R1 must be configured with the same values on the connecting interface.
- ✗
Configure 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40' on R2's interface to match R1's default timers.
Why it's wrong here
This choice fails because it changes R2 rather than R1, directly violating the question's constraint to modify only R1. The default timers on R1 are already hello 10 and dead 40, so applying these commands to R2 would reset R2 away from its configured non-default values and would not achieve the goal of making R1 match R2. OSPF neighbor formation requires the hello and dead intervals on the shared link to be identical; the scenario demands that R1 be reconfigured to 5/20, not that R2 be altered.
- ✗
Configure 'ip ospf hello-interval 5' on R1's GigabitEthernet0/0 interface only; the dead interval will adjust automatically.
Why it's wrong here
This is incorrect because OSPF does not automatically adjust the dead interval when the hello interval is changed. The dead interval must be explicitly configured to match; otherwise, it remains at the default (40) or previous value.
- ✗
Configure 'ip ospf dead-interval 20' on R1's GigabitEthernet0/0 interface only; the hello interval will adjust automatically.
Why it's wrong here
Configuring only the dead interval to 20 on R1's interface sets that timer to match R2's dead interval, but the hello interval remains at its default of 10, while R2 advertises a hello of 5. OSPF does not automatically adjust the hello interval when the dead interval is changed—these parameters are configured independently. Because the hello intervals differ (5 vs. 10), R1 and R2 will not exchange valid hello packets and cannot form an OSPF adjacency, regardless of the matching dead intervals.
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.
✓Configure 'ip ospf hello-interval 5' and 'ip ospf dead-interval 20' on R1's GigabitEthernet0/0 interface.Correct answer▾
Why this is correct
This is correct because OSPF requires matching hello and dead timers on both routers for adjacency formation. R2 uses hello 5 and dead 20, so R1 must be configured with the same values on the connecting interface.
✗Configure 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40' on R2's interface to match R1's default timers.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the instruction limits changes to R1 only; modifying R2 is not allowed.
Why candidates choose this
Candidates might think it's acceptable to change either router, but the question restricts adjustments to R1.
✗Configure 'ip ospf hello-interval 5' on R1's GigabitEthernet0/0 interface only; the dead interval will adjust automatically.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the dead interval is not automatically derived from the hello interval; it must be set separately.
Why candidates choose this
Candidates may recall that the dead interval is typically four times the hello interval and assume it adjusts automatically, but Cisco IOS requires explicit configuration.
✗Configure 'ip ospf dead-interval 20' on R1's GigabitEthernet0/0 interface only; the hello interval will adjust automatically.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the hello interval is not automatically derived from the dead interval; both must be set explicitly.
Why candidates choose this
Candidates may assume that setting the dead interval alone will cause the hello interval to adjust proportionally, but this is not the case in Cisco IOS.
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?”
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
Go deeper
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Key term
OSPFv2
OSPFv2 is a network routing protocol that helps routers share information about the best paths to send data across an IP network.
Key term
OSPF
OSPF is a link-state routing protocol used to find the best path for data packets to travel across IP networks, like a smart GPS that recalculates routes when traffic changes.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.