CCNA IP Routing Practice Question
Network Topology
You are connected to R1 via the console. Configure single-area OSPFv2 on R1, R2, and R3 so that all three routers can exchange routes. The current configuration has mismatched hello/dead timers on the link between R1 and R2, and an area mismatch on the link between R2 and R3. Correct these issues and ensure OSPF adjacencies form.
⚠ Common exam trap
A common trap is to assume that timers must be changed on the router with the 'non-default' values, but OSPF requires timers to match on both ends; either router can be adjusted. Another trap is to think that the area mismatch can be resolved by changing the area on either router, but the correct area must be consistent with the network design. In this scenario, the existing explanation specifies the correction on R2.
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
✓
On R2, configure interface G0/0 with 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40', and modify the OSPF network statement for 10.0.23.0/30 to area 0.
The adjacency between R1 and R2 fails because R1 has hello/dead timers of 10/40, while R2 has 30/120 on G0/0. The adjacency between R2 and R3 fails because R2's G0/1 is in area 1, but R3's G0/1 is in area 0. On R2, change the hello/dead timers on G0/0 to match R1 (10/40) using 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40'. Also change the network statement for 10.0.23.0/30 to area 0 using 'network 10.0.23.0 0.0.0.3 area 0'. Verify with 'show ip ospf neighbor' on all routers.
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 R2, configure interface G0/0 with 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40', and modify the OSPF network statement for 10.0.23.0/30 to area 0.
Why this is correct
This is correct because it fixes both issues: the hello/dead timers on R2's G0/0 are set to match R1's timers (10/40), and the network statement for the link between R2 and R3 is changed to area 0, resolving the area mismatch. After these changes, OSPF adjacencies will form on both links.
- ✗
On R2, configure interface G0/0 with 'ip ospf hello-interval 30' and 'ip ospf dead-interval 120', and modify the OSPF network statement for 10.0.23.0/30 to area 1.
Why it's wrong here
This is incorrect because it changes the timers on R2 to match R2's current timers (30/120) instead of R1's (10/40), which would not resolve the mismatch. Additionally, changing the network statement to area 1 would keep the area mismatch with R3, which is in area 0.
- ✗
On R1, configure interface G0/0 with 'ip ospf hello-interval 30' and 'ip ospf dead-interval 120', and on R3, change the OSPF network statement for 10.0.23.0/30 to area 1.
Why it's wrong here
This is incorrect because it changes R1's timers to match R2's (30/120) instead of the other way around, and changes R3's area to area 1, which would still leave the area mismatch if R2 remains in area 1. The correct approach is to adjust R2 to match R1's timers and change R2's area to area 0.
- ✗
On R1, configure interface G0/0 with 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40', and on R2, modify the OSPF network statement for 10.0.23.0/30 to area 1.
Why it's wrong here
This is incorrect because R1 already has timers of 10/40, so reconfiguring them is unnecessary and does not fix the mismatch. Changing the network statement on R2 to area 1 would keep the area mismatch with R3, which is in area 0.
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 R2, configure interface G0/0 with 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40', and modify the OSPF network statement for 10.0.23.0/30 to area 0.Correct answer▾
Why this is correct
This is correct because it fixes both issues: the hello/dead timers on R2's G0/0 are set to match R1's timers (10/40), and the network statement for the link between R2 and R3 is changed to area 0, resolving the area mismatch. After these changes, OSPF adjacencies will form on both links.
✗On R2, configure interface G0/0 with 'ip ospf hello-interval 30' and 'ip ospf dead-interval 120', and modify the OSPF network statement for 10.0.23.0/30 to area 1.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the timers should be made consistent by adjusting R2 to match R1, not the other way around, and the area mismatch requires both routers to be in the same area, which is area 0.
Why candidates choose this
Candidates might think that changing timers on R2 to match its own current values is correct, or that the area should be changed to area 1 to match R2's current configuration, but this would not fix the adjacency with R3.
✗On R1, configure interface G0/0 with 'ip ospf hello-interval 30' and 'ip ospf dead-interval 120', and on R3, change the OSPF network statement for 10.0.23.0/30 to area 1.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the timers can be adjusted on either router, but the area mismatch must be resolved by making both routers use the same area. Changing R3 to area 1 would not fix the adjacency if R2 is already in area 1? Actually, R2 is in area 1 on G0/1, so changing R3 to area 1 would make them match, but the question states the area mismatch is on the link between R2 and R3, and the existing explanation says to change R2's network statement to area 0. This option changes R3 instead, which could also work, but the question expects the correction on R2 as per the existing explanation. Additionally, changing R1's timers is not the most efficient if R1 is already configured correctly.
Why candidates choose this
Candidates might think that adjusting the router with the 'wrong' timers (R1) is necessary, or that changing the area on R3 is a valid alternative, but the existing explanation specifies the correction on R2.
✗On R1, configure interface G0/0 with 'ip ospf hello-interval 10' and 'ip ospf dead-interval 40', and on R2, modify the OSPF network statement for 10.0.23.0/30 to area 1.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the timers on R1 are already correct, and the area mismatch requires both routers to be in the same area. Changing R2's area to area 1 would not match R3's area 0.
Why candidates choose this
Candidates might think that reconfiguring R1's timers is needed to 'ensure' they are correct, or that changing the area to area 1 on R2 is a valid fix, but it does not resolve the mismatch.
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
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Key term
OSPF
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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.