Huawei HCIP-Datacom H12-831_V1.0 Question # 40 Topic 5 Discussion

Comprehensive and Detailed In-Depth Explanation:

1. Understanding OSPF Neighbor Relationships

OSPF (Open Shortest Path First) forms neighbor relationships based on these key conditions:

Routers must be in the same OSPF area.

The subnet mask and network type must match.

The Hello/Dead timers must match.

Authentication (if enabled) must match.

2. Analyzing the Given Scenario

R1 and R2 are in Area 0 (Backbone Area).

R3 and R4 are in Area 1 (Non-Backbone Area).

R4 was configured incorrectly using R3’s backup configuration, which could cause issues.

3. Evaluating Each Answer Option

Option A: "The OSPF neighbor relationship between R1 and R2 is not affected."

Correct.

R1 and R2 are both in Area 0 and their configuration was not changed.

Since R4 was added only between R2 and R3, it does not impact R1 and R2.

✅ A is correct.

Option B: "An OSPF neighbor relationship can be established between R2 and R4."

Incorrect.

R2 is in Area 0, but R4 is incorrectly configured using R3’s backup, which likely placed it in Area 1.

OSPF neighbors cannot form across different areas unless an Area Border Router (ABR) is properly configured.

Since there is no indication of an ABR setup, the adjacency will fail.

❌ B is incorrect.

Option C: "An OSPF neighbor relationship can be established between R3 and R4."

Correct.

R3 and R4 are both in Area 1, and R4's backup configuration comes from R3, meaning they likely have identical settings.

Since they share the same area and are directly connected, an OSPF adjacency is possible.

✅ C is correct.

Option D: "An OSPF neighbor relationship can be established between R1 and R3."

Incorrect.

R1 is in Area 0, and R3 is in Area 1.

OSPF does not form neighbor relationships between different areas unless configured as an ABR, which is not mentioned.

❌ D is incorrect.

Final Answer:

✅ A and C are correct.

HCIP-Datacom-Advanced Routing & Switching Technology References:

OSPF Neighbor Formation and Area Design Principles

Troubleshooting OSPF Area Mismatches and Configuration Issues

OSPF Backbone Area (Area 0) and Inter-Area Communication