Free Practice Questions for Huawei H12-831_V1.0 Exam

Comprehensive and Detailed In-Depth Explanation:

Understanding the network connectivity:

R1 and R2 are connected through 10.0.12.0/24 and running OSPF in Area 0.

PC1 (192.168.1.11/24) is connected to R1, and PC2 (192.168.1.12/24) is connected to R2.

Analyzing each option:

Option A: " R2 cannot ping 10.0.12.1. " ❌ Incorrect

R2 is directly connected to 10.0.12.1/24 (R1) on GE0/0/0, so it can ping this IP without any routing issues.

Option B: " PC1 and PC2 cannot ping each other. " ✅ Correct

OSPF is only running between R1 and R2. There is no indication that R1 and R2 are redistributing connected routes (192.168.1.0/24 and 192.168.1.0/24) into OSPF.

As a result, R1 does not know how to reach 192.168.1.12, and R2 does not know how to reach 192.168.1.11, making communication between PC1 and PC2 impossible.

Option C: " R1 cannot ping 192.168.1.2. " ❌ Incorrect

192.168.1.2 is directly connected to R2, and if R1 can reach R2 through OSPF, then R1 should be able to ping 192.168.1.2.

Option D: " R1 cannot ping 192.168.1.12. " ✅ Correct

192.168.1.12 is connected to R2, but if R2 does not advertise this network to R1, R1 has no route to reach it.

Since PC1 (192.168.1.11) and PC2 (192.168.1.12) are on different subnets, and there ' s no redistribution, R1 cannot reach PC2 ' s IP.

Key Takeaways and Fix Recommendations:

To allow PC1 and PC2 to communicate, R1 and R2 must advertise their directly connected networks (192.168.1.0/24) in OSPF using the network command or by redistributing connected routes into OSPF.

Command example:

makefile

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R1:

router ospf 1

network 192.168.1.0 0.0.0.255 area 0

R2:

router ospf 1

network 192.168.1.0 0.0.0.255 area 0

This would allow R1 to learn about PC2 ' s network and R2 to learn about PC1 ' s network, enabling communication.

HCIP-Datacom-Advanced Routing & Switching Technology References:

HCIP-Datacom Official Certification Guide, Chapter on OSPF Network Design and Troubleshooting.

Huawei Datacom Training Materials, Section on OSPF Inter-Area and External Route Advertisements.

Huawei Datacom Configuration Guide, Command Reference for OSPF network advertisement and route redistribution.

This statement is false. In Huawei ' s implementation of BGP Route Reflectors:

Each RR (Route Reflector) and its clients form a cluster identified by a cluster ID.

When an RR reflects a route:

If the Cluster_List is empty, it adds the local cluster ID.

If the Cluster_List already contains values, it adds the local cluster ID to the beginning of the list.

So the RR does modify the Cluster_List by adding its own cluster ID regardless of whether the list is empty or not.

✅ Official Reference from Huawei:

" When an RR reflects a route, it adds its own Cluster_ID to the Cluster_List attribute regardless of whether the Cluster_List is empty or not. This mechanism prevents routing loops. "

— [Huawei HCIA-Datacom Certification Guide – BGP Route Reflector Section]

This IS-IS network includes:

R1 as a Level-1 router (area-internal only)

R2 as a Level-1-2 router (acts as a border between L1 and L2)

R3 as a Level-2 router (external to area 49.0001)

The command on R1:

plaintext

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default-route-advertise always level-1

means R1 advertises a default route (0.0.0.0/0) to other Level-1 routers. This helps L1 routers like R1 route toward unknown destinations via R2.

Now analyzing each option:

✅ Option A: 10.0.2.2 can ping 10.0.3.3✔ CorrectR2 is Level-1-2 and has a Level-2 adjacency to R3. So R2 (10.0.2.2) can reach R3’s loopback (10.0.3.3).

✅ Option B: 10.0.12.2 can ping 10.0.3.3✔ Correct10.0.12.2 is on R2, and R2 has full visibility of R3 through Level-2. Thus, it can route traffic to 10.0.3.3.

❌ Option C: 10.0.1.1 can ping 10.0.3.3✖ IncorrectR1 is Level-1 only and cannot see Level-2-only destinations like 10.0.3.3. There is no route leaking from R2’s L2 database into the L1 area.

✅ Option D: 10.0.1.1 can ping 10.0.2.2✔ CorrectBoth are in the Level-1 area (49.0001). The IS-IS Level-1 adjacency allows reachability between these loopbacks.

✅ Official Huawei Extract:

" In IS-IS, Level-1 routers cannot learn Level-2-only routes unless route leaking is configured. A Level-1-2 router like R2 can route between L1 and L2 domains. The command default-route-advertise always level-1 causes R2 to advertise a default route into the Level-1 area, enabling R1 to forward unknown destinations. However, L1 routers still cannot reach L2-only loopbacks like R3’s unless route leaking is explicitly configured. "

— [Huawei HCIA-Datacom Certification Guide – Chapter: IS-IS Route Types and Default Route Advertisement]

Comprehensive and Detailed In-Depth Explanation:

1. Understanding the Network Setup

PC1 (192.168.1.1/24) and PC2 (192.168.1.2/24) are connected to SW1.

Both PCs are in the same VLAN, meaning communication should work without routing.

If there is a communication failure, it could be due to physical, VLAN, ARP, or port security issues.

2. Evaluating Each Answer Option

Option A: " SW1’s GE0/0/2 is shut down. "

Correct.

If GE0/0/2 is shut down, PC2 cannot send or receive traffic, causing communication failure.

Even if PC1 is working, PC2 will be unreachable.

✅ A is a valid cause.

Option B: " The link of SW1’s GE0/0/1 is faulty. "

Correct.

If GE0/0/1 has a faulty link, PC1 cannot communicate with PC2, causing failure.

Even if PC2 is working, PC1 will be unreachable.

✅ B is a valid cause.

Option C: " Incorrect static ARP entries are configured on the hosts. "

Correct.

If static ARP entries are incorrectly configured, PCs will map the wrong MAC addresses to IPs.

This will result in packet delivery failures, even if the physical network is working.

✅ C is a valid cause.

Option D: " Port isolation is configured on SW1. "

Correct.

Port isolation (or private VLAN) prevents direct communication between specific ports.

If port isolation is enabled on GE0/0/1 and GE0/0/2, PC1 and PC2 will be unable to reach each other.

✅ D is a valid cause.

Final Answer:

✅ A, B, C, and D are correct.

HCIP-Datacom-Advanced Routing & Switching Technology References:

Troubleshooting VLAN and Layer 2 Communication Issues

Impact of Port Isolation and Private VLANs on Communication

Static ARP Entry Configuration and Its Effects on Network Connectivity

Comprehensive and Detailed In-Depth Explanation:

Understanding the Spanning Tree Protocol (STP) and Root Bridge Selection

Spanning Tree Protocol (STP) is used to prevent loops in a Layer 2 network by electing a Root Bridge and determining a loop-free topology.

The Root Bridge is elected based on the lowest Bridge ID (BID), which consists of:

Priority Value (Lower is preferred, default is 32768).

MAC Address (Lower MAC wins in case of a tie).

The optimal forwarding path is chosen based on cost, which is usually determined by the link bandwidth.

Why the Path is Not Optimal?

The network engineer states that all links have the same cost, meaning that the STP Root Bridge election determines the topology rather than cost differences.

The fact that the path between PC1 and PC2 is suboptimal suggests that the Root Bridge may not be ideally placed.

Determining the Likely Root Bridge:

The Root Bridge is the switch with the lowest BID (priority + MAC).

All switches calculate the shortest path to the Root Bridge and place ports in either Forwarding or Blocking mode.

From the diagram, the traffic is flowing through SW2 → SW4 → SW3 instead of directly via SW2 → SW3.

This suggests that the Root Bridge is likely SW1 or SW4 because:

Root Bridges do not block any ports.

If SW1 or SW4 is the Root Bridge, the spanning tree topology might force the path to take a longer route.

Key Takeaways:

Root Bridge selection influences the entire Layer 2 forwarding path.

The lowest Bridge ID (priority + MAC) determines the Root Bridge.

If a suboptimal path is taken, the Root Bridge is likely placed in a location that forces certain links to block.

In this scenario, SW1 or SW4 is the most probable Root Bridge, forcing traffic through an unintended path.

HCIP-Datacom-Advanced Routing & Switching Technology References:

Huawei HCIP-Datacom Official Certification Guide, Chapter on Spanning Tree Protocol (STP) and Root Bridge Selection.

Huawei Datacom Training Materials, Section on STP Convergence and Network Optimization.

Huawei Datacom Configuration Guide, Command Reference for STP Root Bridge Selection and Path Calculation.