Free Huawei H12-831_V1.0 Practice Exam with Questions & Answers | Set: 5

Comprehensive and Detailed In-Depth Explanation:

Key OSPF Concepts to Consider:

Area 1 is an NSSA (Not-So-Stubby Area):

NSSAs allow external routes but advertise them as Type-7 LSAs.

The ABR (R2) converts these Type-7 LSAs into Type-5 LSAs for the backbone (Area 0).

Area 2 is a Stub Area:

Stub areas do not allow external routes (Type-5 LSAs).

This means that R5 (inside Area 2) will NOT receive external routes like 10.0.4.4/32 or 10.0.4.0/24.

Effect of asbr-summary 10.0.4.0 255.255.255.0 on R1 and R3:

This command ensures that R1 and R3 will see a summarized route 10.0.4.0/24 instead of specific /32 routes.

Routing Table Analysis:

R1 (ABR for NSSA, with ASBR summary configured)

Connected to Area 1 (NSSA) and Area 0 (Backbone)

Since asbr-summary 10.0.4.0 255.255.255.0 is configured on R1, it contains both 10.0.4.4/32 (from R4) and the summarized 10.0.4.0/24.

✅ Matches Option 4: The routing table contains both 10.0.4.4/32 and 10.0.4.0/24.

R5 (Inside Area 2 - Stub Area)

Stub areas do not receive external routes (Type-5 LSAs).

Since R5 is inside a stub area, it does not contain 10.0.4.4/32 or 10.0.4.0/24.

✅ Matches Option 3: The routing table does not contain 10.0.4.4/32 or 10.0.4.0/24.

R2 (ABR between NSSA and Backbone, but no ASBR summary configured)

R2 converts Type-7 LSAs from R4 into Type-5 LSAs and advertises them into Area 0.

Since no ASBR summary is configured on R2, it only sees the specific external route 10.0.4.4/32 but not the summarized 10.0.4.0/24.

✅ Matches Option 1: The routing table contains 10.0.4.4/32 only.

R3 (Another ABR with ASBR summary configured)

R3 has asbr-summary 10.0.4.0 255.255.255.0 configured, which means it will summarize the external routes.

Instead of 10.0.4.4/32, R3 will only have the summarized 10.0.4.0/24 route.

✅ Matches Option 2: The routing table contains 10.0.4.0/24 only.

References:

HCIP-Datacom-Advanced Routing & Switching Technology V1.0 – OSPF Areas (Stub, NSSA, and Backbone)

OSPF External Route Advertisement and Summarization

OSPF NSSA Behavior and Type-7 to Type-5 Conversion

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:

To determine the correct matches, we need to analyze VLAN aggregation and MUX VLAN behavior in the given topology.

1. Understanding VLAN Aggregation and MUX VLAN Roles

VLAN Aggregation:

Sub-VLANs (e.g., VLAN 10) are part of a Super-VLAN (e.g., VLAN 100) and share a common gateway.

Hosts in the same Sub-VLAN can communicate directly.

MUX VLAN (Multiple User Group VLAN):

Principal VLAN (VLAN 30): Includes servers, accessible by all VLAN types.

Separate VLAN (VLAN 20): Cannot communicate with other Separate VLAN hosts, but can communicate with the Principal VLAN (Server).

Group VLAN (VLAN 10 - Sub-VLANs): Hosts within the same Group VLAN can communicate, and they can also access the Principal VLAN (Server).

2. Analyzing the Connectivity

PC1 (Sub-VLAN 10 - Employee VLAN)

Can communicate with PC2 (same Sub-VLAN).

Can communicate with the Server (VLAN 30 - Principal VLAN).

PC2 (Sub-VLAN 10 - Employee VLAN)

Can communicate with PC1 (same Sub-VLAN).

Can communicate with the Server (VLAN 30 - Principal VLAN).

PC3 (VLAN 20 - Separate VLAN - Guest VLAN)

Cannot communicate with other PCs in Employee VLAN (PC1, PC2) or Guest VLAN (PC4).

Can communicate with the Server (VLAN 30 - Principal VLAN).

PC4 (VLAN 20 - Separate VLAN - Guest VLAN)

Cannot communicate with other PCs in Employee VLAN (PC1, PC2) or Guest VLAN (PC3).

Can communicate with the Server (VLAN 30 - Principal VLAN).

Server (VLAN 30 - Principal VLAN)

Can communicate with all PCs (PC1, PC2, PC3, PC4) because it belongs to the Principal VLAN, which serves all VLANs.