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

Comprehensive and Detailed In-Depth Explanation:

Understanding OSPFv3 Areas and Routing Behavior

OSPFv3 Area Types in the Network:

Area 1 (Stub Area): Does not accept external LSAs (Type 5) but can receive Inter-Area-Prefix-LSAs (Type 3).

Area 2 (Common Area): Fully functional area that allows both Type 3 (Inter-Area) and Type 5 (External) LSAs.

Area 3 (NSSA - Not-So-Stubby Area): Does not accept Type 5 (External) LSAs but allows ASBRs to inject external routes using Type 7 LSAs, which are later converted to Type 5 in other areas.

Effect of stub no-summary Command on Area 1 (Configured on R2):

This command prevents Type 3 LSAs from entering Area 1, meaning R4 will not learn about 2000::6/128 from other areas.

R4 only has a default route (::/0) provided by R2 but not individual routes like 2000::6/128.

Route and Packet Flow Analysis

A. " The LSDB of R4 contains the Inter-Area-Prefix-LSA that is generated by R1 and describes 2000::6/128. " ❌ (False)

R4 is in Area 1 (a totally stub area), which does not receive Type 3 LSAs.

Since 2000::6/128 is an external route from Area 2, it will not be present in R4’s LSDB.

Thus, R4 does NOT have the Inter-Area-Prefix-LSA for 2000::6/128.

❌ Statement A is incorrect.

B. " The path for data packets from R4 to 2000::6 is R4 - > R1 - > R5 - > R3 - > R6. " ❌ (False)

R4 is in a totally stub area (Area 1), and it does not have a specific route for 2000::6/128.

It only has a default route (::/0) pointing to R2.

If R4 forwards traffic, it will send it to R2, NOT via R1, R5, and R3.

❌ Statement B is incorrect.

C. " The routing table of R4 does not contain the route 2000::6/128. " ✅ (True - Correct Answer)

R4 is in a totally stub area (Area 1), meaning it only receives a default route from R2 (::/0).

It does NOT receive specific routes like 2000::6/128.

✅ Statement C is correct.

D. " The path for data packets from R4 to 2000::6 is R4 - > R2 - > R6. " ❌ (False)

While R4 does forward all unknown traffic to R2 (due to the default route), R2 will NOT directly forward to R6.

R2 is an ABR (Area Border Router), and the actual path to 2000::6 must traverse Area 2, likely through other routers.

❌ Statement D is incorrect.

Final Conclusion:

✅ C. The routing table of R4 does not contain the route 2000::6/128.

Thus, the correct answer is: C. The routing table of R4 does not contain the route 2000::6/128.

Comprehensive and Detailed In-Depth Explanation:

This question involves IS-IS, iBGP, and route reflection, but unlike Question 2, it does not mention the import-route isis level-2 into level-1 command. We’ll re-analyze each statement, considering the possibility of multiple correct answers, and ensure alignment with HCIP-Datacom principles.

A. The routing table of R4 contains two equal-cost default routes.

Analysis:

R4 is a Level-1/Level-2 router in area 49.0001. It can learn default routes from Level-2 routers (R2, R5) if they advertise them (e.g., via default-route-advertise).

The question does not specify default route advertisement or equal-cost paths. IS-IS prefers the closest Level-2 router, and the topology suggests a single path (e.g., via R2 or R5), not two equal-cost paths.

Without ECMP or specific configuration, R4 would not have two equal-cost default routes.

Conclusion: This statement is false.

B. The route 192.168.1.0/24 in the routing table of R3 has two next hops.

Analysis:

The route 192.168.1.0/24 is imported into BGP by R1 and R4 (in area 49.0001) and reflected by R2 and R5 to their iBGP clients, including R3 (in area 49.0002).

The next-hop for this route, as received via iBGP, would typically point to R1 or R4 unless next-hop-self is configured on R2 or R5.

R3, in area 49.0002 (Level-2), needs an IS-IS path to reach R1 or R4 (in area 49.0001). Without the import-route isis level-2 into level-1 command (not mentioned here), standard IS-IS behavior applies: Level-2 routers (R3) cannot directly learn Level-1 routes unless redistributed or via Level-2 connectivity.

R3 relies on IS-IS Level-2 routes via R2 or R5 to reach R1/R4. The question does not indicate multiple equal-cost IS-IS paths from R3 to R1 and R4 (e.g., via both R2 and R5 with the same cost).

Without ECMP or equal-cost paths, R3 would use a single next hop to reach 192.168.1.0/24.

However, if R2 and R5 both reflect the route with the same cost to R1 and R4, and IS-IS provides equal-cost paths to both next-hops, R3 could have two next hops if ECMP is enabled.

The topology and lack of cost details suggest this is unlikely without explicit configuration, making this statement false in standard scenarios.

Conclusion: This statement is false, as there’s no clear evidence of ECMP or equal-cost paths.

C. The routing table of R1 does not contain the route 192.168.2.0/24.

Analysis:

The route 192.168.2.0/24 is imported into BGP by R3 and R6 (in area 49.0002) and reflected by R2 and R5 to their iBGP clients, including R1 (in area 49.0001).

iBGP ensures the route is propagated within AS 65000, so R1, as an iBGP client, will receive 192.168.2.0/24.

R1, in area 49.0001 (Level-1/Level-2), needs an IS-IS path to the next-hop (R3 or R6). Without the import-route isis level-2 into level-1 command, standard IS-IS behavior applies: Level-1 routers (R1) cannot learn Level-2 routes (to R3, R6) unless redistributed or via Level-2 connectivity through R2 or R5.

Since R2 and R5 are Level-2 routers connecting the areas, R1 can learn IS-IS routes to R3 and R6 via Level-2, allowing it to resolve the next-hop and install 192.168.2.0/24 in its routing table.

Therefore, R1’s routing table contains 192.168.2.0/24, making this statement false.

Conclusion: This statement is false.

D. For 192.168.1.0/24, R3 preferentially selects the BGP route received from R2, and R6 preferentially selects the BGP route received from R5.

Analysis:

The route 192.168.1.0/24 is imported into BGP by R1 and R4 (in area 49.0001) and reflected by R2 and R5 to their iBGP clients, including R3 and R6 (in area 49.0002).

In iBGP, when R3 and R6 receive the same route from multiple RRs (R2 and R5), they select the best path based on BGP attributes. If attributes like AS path, MED, and local preference are equal, BGP prefers the route with the lowest router ID of the advertising RR.

The router IDs are 10.0.0.2 for R2 and 10.0.0.5 for R5. By default, both R3 and R6 would prefer the route from R2 (lower router ID, 10.0.0.2 < 10.0.0.5).

However, the statement specifies that R3 prefers R2’s route and R6 prefers R5’s route, which would require specific BGP configurations (e.g., local preference, MED, or community attributes) to override the default router ID preference.

The question does not mention such configurations, but the statement’s wording suggests an implied or configured scenario common in HCIP-Datacom exams.

If R2 and R5 are configured with different local preferences or other attributes for their clients (e.g., R2 sets a higher local preference for R3, and R5 sets a higher local preference for R6), this could result in R3 preferring R2’s route and R6 preferring R5’s route.

Given the exam context and the possibility of multiple correct answers, D is true if we interpret the statement as reflecting a configured scenario where R3 and R6 have been set up to prefer routes from R2 and R5, respectively, for 192.168.1.0/24. This aligns with typical HCIP-Datacom questions testing BGP path selection policies.

Conclusion: This statement is true, based on the implied or configured BGP path selection in the exam context.

A PE imports a VPNv4 route only when at least one RT attached to that route matches an Import RT configured in the receiving VPN instance. Bidirectional communication therefore requires reciprocal matching:

Site1/Site2 ERT must match Site3 IRT.

Site3 ERT must match Site1/Site2 IRT.

Evaluation of the displayed configurations:

Option A — Correct: All PEs export and import 100:1. All three sites import one another’s routes, providing full-mesh communication.

Option B — Incorrect: PE1 exports 200:1, but PE3 imports only 100:1; PE3 exports 200:1, but PE1 imports only 100:1. Consequently, Site1 and Site3 cannot exchange routes bidirectionally.

Option C — Correct: Site1 exchanges routes with Site3 through RT 100:1, while Site2 exchanges routes with Site3 through RT 200:1. PE3 imports and exports both RTs. This supports Site1-to-Site3 and Site2-to-Site3 communication while maintaining separate RT groups for Site1 and Site2.

Option D — Correct: PE1 and PE2 export 200:1, which PE3 imports. PE3 exports 100:1, which PE1 and PE2 import. This is a valid hub-and-spoke RT design with Site3 functioning as the hub.

Huawei specifies that one site’s Export RT must match the other site’s Import RT, and the reverse matching must also exist for bidirectional communication. Huawei BGP/MPLS IP VPN configuration guide

Comprehensive and Detailed In-Depth Explanation:

To determine the correct answer, we need to analyze how each command impacts OSPF neighbor relationships.

1. Understanding OSPF Neighbor Formation

OSPF routers form neighbor relationships when they meet the following conditions:

They are in the same subnet (IP addresses and subnet masks must match).

They are in the same OSPF area.

They use the same network type (e.g., Broadcast, Point-to-Point).

Authentication (if configured) must match.

Hello and Dead timers must match.

2. Analyzing Each Answer Option

❌ A. " undo ip address 10.0.12.2 24 " → Affects OSPF Neighbor Status

Removing the IP address will prevent the interface from sending and receiving OSPF Hello packets.

Without an IP address, OSPF cannot establish neighbor relationships.

Effect: Breaks OSPF neighbor status.

✅ B. " undo description " → Does NOT Affect OSPF Neighbor Status

The interface description is just a label for administrators and has no impact on OSPF functionality.

It does not affect neighbor relationships, routing, or communication.

Effect: No impact on OSPF neighbors.

❌ C. " undo ospf cost " → Affects OSPF Neighbor Status Indirectly

OSPF cost determines the path selection but does NOT break the neighbor relationship.

However, if the cost change leads to routing table recalculations, it might cause temporary convergence issues.

Effect: Does not directly break neighbor status, but affects route selection.

❌ D. " undo ospf dr-priority " → Affects OSPF Neighbor Status (Possibly Causes DR Re-Election)

OSPF DR/BDR election uses priority values.

If changed, a new election might occur, leading to a temporary loss of neighbor relationships.

Effect: Might cause OSPF neighbor reset (temporary impact on adjacency).

Comprehensive and Detailed In-Depth Explanation:

Understanding Intra-Area-Prefix-LSA (Type 9) in OSPFv3

OSPFv3 uses the Intra-Area-Prefix-LSA (Type 9) to advertise IPv6 prefixes associated with either:

A Router-LSA (Type 1) → Describes links and interfaces.

A Network-LSA (Type 2) → Advertises multi-access networks (if a Designated Router exists).

Each router generates one Intra-Area-Prefix-LSA to advertise its own IPv6 prefixes.

Prefix Analysis for Each Router

R1 ' s IPv6 Prefixes:

2000:12::1/64

2001:12::1/64

2002:12::1/64

2003:12::/64 (Shared link with R2)

Total Prefixes in R1’s Intra-Area-Prefix-LSA = 4

✅ R1 advertises four prefixes in its Intra-Area-Prefix-LSA.

R2 ' s IPv6 Prefixes:

2003:12::2/64 (Shared link with R1)

Total Prefixes in R2’s Intra-Area-Prefix-LSA = 1

✅ R2 advertises only one prefix in its Intra-Area-Prefix-LSA.

Checking Each Option:

✅ A. The Intra-Area-Prefix-LSA generated by R2 describes three prefixes. (❌ False, R2 only has one prefix).

✅ B. The Intra-Area-Prefix-LSA generated by R1 describes four prefixes. (✔ True, R1 has four prefixes).

✅ C. The Intra-Area-Prefix-LSA generated by R2 describes four prefixes. (❌ False, R2 only has one prefix).

✅ D. The Intra-Area-Prefix-LSA generated by R1 describes three prefixes. (❌ False, R1 has four prefixes).

Final Conclusion:

✅ B. The Intra-Area-Prefix-LSA generated by R1 describes four prefixes.

Thus, the correct answer is: B. The Intra-Area-Prefix-LSA generated by R1 describes four prefixes.