H12-831_V1.0 HCIP-Datacom-Advanced Routing & Switching Technology V1.0 Questions and Answers

Comprehensive and Detailed In-Depth Explanation:

Understanding the LSA Table in the Figure

The LSDB (Link-State Database) of R4 displays an Intra-Area-Prefix-LSA for Area 0.0.0.1. The table contains:

Three LSAs originating from R4 (10.0.4.4)

Prefixes referencing both Router-LSAs and Network-LSAs

Different Sequence Numbers and Checksums, indicating multiple link-state changes

OSPFv3 LSA Types Relevant to the Question

Router-LSA (Type 1)

Generated by every router to describe its links within an area.

Network-LSA (Type 2)

Generated only by the Designated Router (DR) for multi-access networks (such as Ethernet).

Advertises all routers connected to the same segment.

Intra-Area-Prefix-LSA (Type 9)

Advertises IPv6 prefixes associated with a Router-LSA (Type 1) or Network-LSA (Type 2).

Analysis of Each Statement

A. The three LSAs belong to area 1. ✅ (True)

The table explicitly shows "Intra-Area-Prefix-LSA (Area 0.0.0.1)", meaning all LSAs are for Area 1.

The Link State IDs also indicate intra-area advertisements.

✅ Statement A is correct.

B. Area 1 is a stub area. ❌ (False)

There is no indication that Area 1 is a stub area.

Stub areas do not receive Type 5 (External) LSAs, and the LSDB does not show Type 3 (Inter-Area) LSAs either.

Network-LSAs (Type 2) are not typically seen in stub areas unless explicitly configured.

❌ Statement B is incorrect.

C. No OSPFv3 neighbor relationship is established on at least one link of R4. ✅ (True)

One LSA references a Router-LSA, while two reference Network-LSAs.

A Router-LSA alone suggests that R4 has at least one point-to-point or unnumbered link with no OSPFv3 adjacency.

This means R4 has an interface with no neighbor (e.g., a passive interface or down link).

✅ Statement C is correct.

D. R4 is the DR on a link. ✅ (True)

The presence of Network-LSAs (Type 2) indicates that a multi-access link exists.

Since R4 is the origin of the Network-LSA, it must be the DR (Designated Router) for that link.

✅ Statement D is correct.

Final Conclusion:

✅ A. The three LSAs belong to area 1. (True)❌ B. Area 1 is a stub area. (False)✅ C. No OSPFv3 neighbor relationship is established on at least one link of R4. (True)✅ D. R4 is the DR on a link. (True)

Thus, the correct answers are: A, C, D.

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:

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.

 Network cable → Use a tester to check connectivity.

 Device version file → Check the size of the software package and check whether the file matches the device model.

 Board → Install the board on a device that is not connected to the network and observe the running status of the device.

 License → Check whether the license is in the validity period to prevent device functions from being affected.

 Migration personnel list → Check whether responsibilities and permissions are clearly assigned.

Comprehensive and Detailed In-Depth Explanation:

1. Network Cable - Connectivity Testing:

Before starting a migration project, all network cables should be tested for physical connectivity issues.

Network testers can be used to detect any breaks, shorts, or incorrect wiring.

Ensuring proper connectivity avoids delays and troubleshooting issues during the migration.

2. Device Version File - Software Compatibility Check:

Firmware and software versions must be verified before upgrading or migrating network devices.

The device version file should match the model and hardware specifications to avoid compatibility issues.

If incorrect software is used, the device may not function properly or could become inoperable.

3. Board - Installation and Hardware Verification:

Before installing new hardware modules (boards, line cards, etc.) into a production environment, they should be tested in isolation.

Testing ensures the board is operational and does not introduce faults into the system.

If a board is faulty, it can cause device failure or unexpected behavior in the migration.

4. License - Validity and Activation Check:

Some network devices require licenses for full functionality (e.g., advanced routing, security features).

If a license is expired or missing, critical functions may be disabled after migration.

Checking license status in advance prevents unexpected downtime or service disruptions.

5. Migration Personnel List - Roles and Responsibilities Assignment:

Large network migrations require clear responsibility assignments for each team member.

A migration personnel list ensures that everyone knows their role, tasks, and permissions.

Proper coordination avoids miscommunication, errors, and project delays.

Key Takeaways:

✅ Network cables should be tested for connectivity.✅ Software versions should match the hardware model to prevent incompatibility.✅ Hardware boards should be tested before installing into production.✅ Licenses should be verified to prevent service disruptions.✅ Migration personnel roles should be clearly defined for smooth execution.

HCIP-Datacom-Advanced Routing & Switching Technology References:

Huawei HCIP-Datacom Official Certification Guide, Chapter on Network Migration Best Practices.

Huawei Enterprise Networking Whitepapers, Guidelines on Software & Hardware Pre-checks for Migration.

Huawei Technical Documentation, License Management in Huawei Datacom Devices.

Comprehensive and Detailed In-Depth Explanation:

1. Understanding the Network Setup

PE1 (Provider Edge 1) is the gateway for network 192.168.1.1/24.

PE2 (Provider Edge 2) is the gateway for network 192.168.2.1/24.

A cloud-based backbone connects PE1 and PE2.

To verify end-to-end communication, engineers need to check reachability between PE1 and PE2.

2. Evaluating Each Answer Option

Option A: "Configuring NQA on PE1 and PE2, with the destination address being the IP address of each other."

✅ Correct.

NQA (Network Quality Analysis) is a network testing tool that allows connectivity testing between two devices.

Configuring NQA between PE1 and PE2 will verify end-to-end reachability.

Option B: "On PE1 and PE2, checking whether the ARP table contains the ARP entry of the peer network segment."

❌ Incorrect.

ARP (Address Resolution Protocol) is only used for resolving MAC addresses within the same broadcast domain.

Since PE1 and PE2 are in different network segments (separated by a routed network), they will not have ARP entries for each other.

Instead, routing entries should be checked, not ARP.

Option C: "On PE1, using 192.168.1.1 as the source address to ping 192.168.2.1."

✅ Correct.

A simple ping test using the source address of PE1 (192.168.1.1) to reach PE2 (192.168.2.1) will verify whether routing between the two locations is functional.

Option D: "On PE1 and PE2, checking whether there are routes to each other’s network segment in the routing tables."

✅ Correct.

If routing is not configured correctly, PE1 and PE2 will not know how to reach each other.

Checking the routing table ensures that both PEs have the correct next-hop information.

Final Answer:

✅ A, C, and D are correct.

HCIP-Datacom-Advanced Routing & Switching Technology References:

Using NQA for Network Connectivity Testing

Verifying Routing Table Entries for Inter-Network Communication

Understanding ARP and Its Limitations in Routed Networks

Comprehensive and Detailed In-Depth Explanation:

Understanding the BGP Network Topology in the Question:

EBGP Peering

Each router forms EBGP peer relationships with directly connected neighbors.

This is a fully meshed topology, meaning each router exchanges BGP routes with its adjacent routers.

Routing Information for 192.168.1.0/24

R1 and R4 import the static route 192.168.1.0/24 into BGP.

Since BGP prefers the shortest AS path, traffic to 192.168.1.0/24 will follow the shortest path to R1 or R4.

Route Analysis for Each Statement:

Statement A: R6 → R5 → R4 ✅ (Correct)

R6 does not have a direct route to 192.168.1.0/24, so it must rely on BGP advertisements from its EBGP neighbors.

R5 learns the route to 192.168.1.0/24 from R4.

Therefore, R6 forwards traffic to R5, and then R5 sends it to R4.

✅ Correct path: R6 → R5 → R4

Statement B: R5 → R4 ✅ (Correct)

R5 is directly connected to R4, and since R4 advertises the 192.168.1.0/24 route via BGP,

R5 will forward traffic directly to R4 as the shortest AS path.

✅ Correct path: R5 → R4

Statement C: R2 → R1 ✅ (Correct)

R2 is directly connected to R1 and learns the 192.168.1.0/24 route from R1 via BGP.

Since R1 advertises the static route, R2 forwards traffic directly to R1.

✅ Correct path: R2 → R1

Statement D: R3 → R2 → R1 ✅ (Correct)

R3 is directly connected to R2 and learns the 192.168.1.0/24 route from R2 via BGP.

Since R2 prefers R1 as the shortest AS path to 192.168.1.0/24,

R3 will send traffic to R2, and R2 will send it to R1.

✅ Correct path: R3 → R2 → R1

Final Conclusion:

✅ A. The path for traffic from R6 to 192.168.1.0/24 is R6 → R5 → R4.✅ B. The path for traffic from R5 to 192.168.1.0/24 is R5 → R4.✅ C. The path for traffic from R2 to 192.168.1.0/24 is R2 → R1.✅ D. The path for traffic from R3 to 192.168.1.0/24 is R3 → R2 → R1.

Thus, the correct answers are: A, B, C, D.

Comprehensive and Detailed In-Depth Explanation:

1. Understanding MPLS Label Stack and the S (Bottom of Stack) Bit

MPLS (Multiprotocol Label Switching) packets can have multiple labels stacked on top of each other.

Each label has the following fields:

Label (20 bits): Identifies the forwarding path.

EXP (3 bits): Used for QoS/priority marking.

TTL (8 bits): Time-to-live, similar to IP TTL.

S (1 bit): Bottom of Stack (BoS) indicator:

S = 0: This is not the last label in the stack.

S = 1: This is the last label in the stack, meaning the next header is the IP header.

2. Analyzing the MPLS Packet Structure in the Figure

The diagram shows three MPLS headers (labels).

The last MPLS header before the IP header must have S = 1, indicating the bottom of the stack.

All other MPLS headers above it must have S = 0, meaning they are part of the stacked labels.

3. Evaluating the Answer Choices

Option

S1

S2

S3

Correct?

Reasoning

A

3

2

1

❌ Incorrect

S field cannot have values greater than 1.

B

2

1

0

❌ Incorrect

S field must be 0 for non-bottom labels.

C

1

1

0

❌ Incorrect

There should be only one label with S = 1 (BoS).

D

0

0

1

✅ Correct

Only the last label should have S = 1.

✅ Correct Answer: D. S1 = 0, S2 = 0, S3 = 1

Final Conclusion:

Only the last MPLS label (closest to the IP header) should have S = 1.

All previous MPLS labels should have S = 0.

Thus, the correct answer is: D. S1 = 0, S2 = 0, S3 = 1

Comprehensive and Detailed In-Depth Explanation:

1. Understanding OSPFv3 and DR/BDR Election

In OSPFv3, on broadcast and non-broadcast networks, routers elect a Designated Router (DR) and a Backup Designated Router (BDR) to reduce LSA flooding.

The DR is responsible for generating Network LSAs (Type 2 LSAs) for the subnet.

The BDR takes over if the DR fails.

Other routers (DROther) only form adjacencies with the DR and BDR but still receive LSAs.

2. Understanding the LSA Output in the Figure

The LSA shown in the figure is a Type 1 (Router LSA).

The originating router is R2 (Router ID: 10.0.2.2).

The LSA lists two "Transit Network" links connected to R2.

The Neighbor Router IDs listed are 10.0.1.1 (R1) and 10.0.2.2 (R2).

3. Why the Statement is FALSE

A transit network (broadcast network) should have only ONE DR.

R1 and R2 both being DRs is incorrect, as only one DR per subnet should exist.

The presence of two "Transit Network" entries in the LSA suggests that there are two separate OSPF broadcast networks, each with its own DR.

This means R1 and R2 are each DRs on separate networks, but not both DRs on the same network.

Final Answer:

Answer: B (FALSE)

HCIP-Datacom-Advanced Routing & Switching Technology References:

OSPFv3 DR/BDR Election Process

OSPFv3 LSA Types and Their Roles

OSPFv3 Network Topology and LSA Interpretation

Comprehensive and Detailed In-Depth Explanation:

To analyze the correct answer, we need to break down the topology and protocol behaviors step by step:

Understanding the IS-IS and OSPFv3 Network Setup:

IS-IS IPv6 is running between R2, R6, and R3.

OSPFv3 is running on other links.

Area 1 is a stub area, which means it does not accept external routes but can have a default route (::/0).

Area 2 is an NSSA (Not-So-Stubby Area), meaning it allows external routes as NSSA external LSAs.

Analysis of Each Answer Option:

A. "The routing table of R6 contains the route ::/0." → FALSE

R6 only participates in IS-IS (Level-1) and does not receive a default route (::/0) from Level-2 routers.

Since R6 is in IS-IS Level-1 and does not have a connection to a Level-2 router that provides a default route, it will not have a ::/0 route in its routing table.

Comprehensive and Detailed In-Depth Explanation:

Step 1: Identify the Primary Path

The shortest OSPF cost to 10.0.3.3/32 from R1 is through R5:

R1 → R5 (Cost 10) → R3 (Cost 10) = Total Cost 20

The primary outbound interface from R1 to R5 is GE0/0/1.

Step 2: Identify the Backup Path (OSPF IP FRR & ECMP)

OSPF IP Fast Reroute (FRR) provides a backup next-hop in case the primary link (R1 → R5) fails.

A feasible backup path must have a cost equal to or close to the primary path, but it must avoid the same failure point.

Alternative Path Calculation:

Path 1 (R1 → R2 → R3)

R1 → R2 (Cost 10), R2 → R3 (Cost 10) → Total Cost = 20 ✅

Uses interface GE0/0/2 on R1.

Path 2 (R1 → R4 → R3)

R1 → R4 (Cost 10), R4 → R3 (Cost 10) → Total Cost = 20 ✅

Uses interface GE0/0/3 on R1.

Final Decision on the Backup Interface

Since both paths R1 → R2 → R3 and R1 → R4 → R3 have equal costs, either can be used for backup.

However, R1 → R2 → R3 shares a direct cost path with R5, meaning it may not be preferred as a full FRR backup.

The best backup outbound interface in this scenario is GE0/0/3 (R1 → R4 → R3).

Final Answer: ✅ C (GE0/0/3)

References:

HCIP-Datacom-Advanced Routing & Switching Technology V1.0 – OSPF IP FRR (Fast Reroute) Mechanism

OSPF Equal-Cost Multi-Path (ECMP) and Backup Route Selection

OSPF Route Calculation and Best-Path Selection

Comprehensive and Detailed In-Depth Explanation:

Step 1: Analyzing the Primary Path

The given network uses IS-IS Auto FRR, which ensures a backup route in case of failure.

The shortest path from R1 to 10.0.3.3/32 is calculated based on the OSPF link costs:

Path 1 (Primary Path): R1 → R2 → R3

Cost: 10 (R1→R2) + 5 (R2→R3) = 15 ✅

Step 2: Checking the Backup Path

The statement claims that the backup path is R1 → R4 → R2 → R3. Let's calculate the cost:

Path 2 (Backup Path via R4): R1 → R4 → R2 → R3

Cost: 10 (R1→R4) + 50 (R4→R2) + 5 (R2→R3) = 65 ❌ (Too high)

The backup path should be an alternative shortest path that is as close as possible to the primary path in cost.

R1 → R4 → R2 → R3 is not a feasible backup path because the cost (65) is significantly higher than the primary path (15).

Step 3: Correct Backup Path Selection

If IS-IS Auto FRR is enabled, a feasible backup path should have a cost close to the primary path.

In this scenario, no viable alternative path meets the Auto FRR requirements efficiently.

The given backup path is incorrect.

Final Answer: ✅ FALSE (Option B)

References:

HCIP-Datacom-Advanced Routing & Switching Technology V1.0 – IS-IS Auto FRR Mechanism

OSPF Route Selection and Fast Reroute Principles

OSPF and IS-IS Path Cost Calculation

Comprehensive and Detailed In-Depth Explanation:In this OSPF network, we need to determine which router does not have the external route 10.0.5.5/32 in its routing table, based on the area types and OSPF behavior for external routes (Type 5 LSAs). Let’s break it down step by step:

Understanding the Network and Area Types:

The network has multiple areas: Area 0 (backbone area), Area 1 (common area), Area 2 (stub area), and Area 3 (Not-So-Stubby Area or NSSA).

Area 0 is the backbone area, connecting all other areas.

Area 1 is a common (regular) area, which allows all types of LSAs, including external routes (Type 5 LSAs).

Area 2 is a stub area, which does not allow external routes (Type 5 LSAs) to be propagated into it. Instead, a default route (0.0.0.0/0) is injected by the Area Border Router (ABR) to provide connectivity to external destinations.

Area 3 is an NSSA, which allows limited external routes (Type 7 LSAs, translated to Type 5 LSAs by the ABR) but can block Type 5 LSAs depending on configuration. However, NSSAs typically allow external routes originated within the NSSA to be advertised into Area 0 and other areas.

External Route Behavior (10.0.5.5/32):

R5, located in Area 3 (NSSA), imports an external route 10.0.5.5/32. In an NSSA, external routes are advertised as Type 7 LSAs within the NSSA and are translated to Type 5 LSAs by the ABR (e.g., R1 or another router connecting Area 3 to Area 0) before being flooded into Area 0 and other areas.

Type 5 LSAs (external routes) are flooded throughout the OSPF domain, except into stub areas and, in some cases, NSSAs (depending on configuration). However, stub areas block Type 5 LSAs entirely, replacing them with a default route.

Analyzing Each Router’s Area and Route Propagation:

R1: Located in Area 0, R1 is an ABR connecting Area 0 to other areas (e.g., Area 1 and Area 3). As an ABR, R1 receives the Type 7 LSA from R5 in Area 3, translates it to a Type 5 LSA, and floods it into Area 0 and other connected areas (except stub areas). Therefore, R1 will have the route 10.0.5.5/32 in its routing table.

R2: Located in Area 0, R2 is also in the backbone area and will receive the Type 5 LSA flooded from Area 0. Thus, R2 will have the route 10.0.5.5/32 in its routing table.

R3: Located in Area 2 (stub area), R3 does not receive Type 5 LSAs because stub areas block external routes. Instead, the ABR (likely R2 or another router connecting Area 2 to Area 0) injects a default route (0.0.0.0/0) into Area 2. Therefore, R3 will not have the specific route 10.0.5.5/32 in its routing table.

R4: Located in Area 2 (stub area), R4, like R3, is in a stub area and does not receive Type 5 LSAs. It relies on the default route injected by the ABR. Thus, R4 will not have the route 10.0.5.5/32 in its routing table.

R5: Located in Area 3 (NSSA), R5 originates the external route 10.0.5.5/32 and advertises it as a Type 7 LSA within Area 3. R5 will have this route in its routing table.

R6: Located in Area 1 (common area), R6 receives the Type 5 LSA flooded from Area 0 (via R1 or another ABR). Therefore, R6 will have the route 10.0.5.5/32 in its routing table.

Identifying the Router Without the Route:

The question asks which router does not have the route 10.0.5.5/32 in its routing table.

R3 and R4 are both in Area 2 (stub area), which blocks Type 5 LSAs. Therefore, neither R3 nor R4 will have the route 10.0.5.5/32.

R6 (Area 1, common area) and R2 (Area 0, backbone) will have the route, as will R1 (Area 0 and ABR) and R5 (Area 3, NSSA, originator).

The options provided are R6, R3, R4, and R2. Among these, R3 and R4 do not have the route, but we need to select one correct answer from the options. Given the typical focus of such questions on identifying a single router in a stub area, and considering the placement of R4 in the diagram (Area 2), R4 is the most likely answer, as it is clearly in the stub area and isolated from external routes.

Conclusion:

R4, located in Area 2 (stub area), does not have the route 10.0.5.5/32 in its routing table because stub areas block Type 5 LSAs, and only a default route is provided by the ABR.

Therefore, the correct answer is C (R4).

References (Based on HCIP-Datacom-Advanced Routing & Switching Technology Concepts):

OSPF Area Types: HCIP-Datacom documentation on OSPF area configurations, including stub areas, NSSAs, and common areas (e.g., Section on OSPF LSA Types and Area Restrictions).

External Route Propagation: HCIP-Datacom coverage of Type 5 and Type 7 LSAs, their flooding behavior, and restrictions in stub and NSSA areas (e.g., Chapter on Advanced OSPF Features).

ABR and ASBR Roles: HCIP-Datacom explanation of Area Border Routers (ABRs) and Autonomous System Boundary Routers (ASBRs) in OSPF networks (e.g., Section on Route Redistribution and External Route Handling).

Comprehensive and Detailed In-Depth Explanation:

Understanding the BGP and OSPF Network Topology in the Question:

External Route Importation

R1, R2, and R3 import 192.168.1.0/24 into BGP from an external source.

This means R1, R2, and R3 will advertise this route to their EBGP and iBGP peers.

BGP Route Selection Criteria

BGP follows specific rules to determine the best path for a route. The most relevant factors here are:

Highest Local Preference (LOCAL_PREF) → Preferred

Shortest AS Path → Preferred

Lowest Origin Type (IGP < EGP < Incomplete) → Preferred

Lowest MED (Multi-Exit Discriminator) → Preferred

Oldest eBGP route (if paths are equal) → Preferred

Route Selection Analysis for Each Statement:

A. For 192.168.1.0/24, R5 preferentially selects the route received from R2. ✅ (Correct)

R5 is in AS 65456 and peers with R6 using iBGP.

Since R2 is a central router with direct connectivity to R5, it is the most preferred path compared to indirect paths from R1 or R3.

By default, R5 will prefer the path from R2 over others unless explicitly influenced by BGP attributes.

✅ Statement A is correct.

B. For 192.168.1.0/24, R4 preferentially selects the route received from R1. ❌ (Incorrect)

R4 and R5 use Loopback0 to establish iBGP with R6, meaning they receive BGP routes from multiple sources.

BGP prefers the shortest AS path, and there is no specific information indicating that R1’s path is the shortest for R4.

R4 may actually prefer another router's advertisement (e.g., R2 or R3) depending on AS path length and other attributes.

❌ Statement B is incorrect.

C. For 192.168.1.0/24, if the default local-preference 150 command is configured on R3, R5 preferentially selects the route received from R3. ✅ (Correct)

By default, BGP assigns a local-preference of 100.

If R3 sets local-preference to 150, it is higher than other routes (R1, R2).

BGP prefers the highest local-preference value, so R5 will prefer the route received from R3 if this attribute is set.

✅ Statement C is correct.

D. For 192.168.1.0/24, R6 preferentially selects the route received from R4. ❌ (Incorrect)

R6 is an iBGP peer of both R4 and R5.

BGP best-path selection depends on attributes like local-preference, AS-path, and MED.

There is no explicit information suggesting that R4’s advertisement is preferred over R5’s.

R6 may prefer R5’s route depending on attributes.

❌ Statement D is incorrect.

Final Conclusion:

✅ A. R5 preferentially selects the route received from R2.❌ B. R4 does not necessarily prefer R1’s route.✅ C. If R3 sets local-preference 150, R5 will prefer the route from R3.❌ D. R6 does not necessarily prefer R4’s route.

Thus, the correct answers are: A, C.

Comprehensive and Detailed In-Depth Explanation:

Understanding the IS-IS Network and IPv6 Route Summary Behavior

IS-IS Areas and Router Roles:

Area 49.0001 (Level-1-2): R1, R2, R4

Area 49.0002 (Level-1-2 & Level-1): R3 (Level-1-2), R5 (Level-1 only)

Effect of ipv6 summary 2000::/64 level-1-2 Command on R4

Route summarization in IS-IS allows an L1-L2 router (R4) to aggregate IPv6 prefixes and advertise a summary route (2000::/64) into both Level-1 and Level-2 areas.

This means R4 will advertise only 2000::/64 instead of specific /128 routes (like 2000::4/128).

All Level-1 and Level-2 routers connected to R4 will receive the summary route 2000::/64 instead of the detailed /128 routes.

Route Distribution Analysis for Each Statement

A. The routing table of R1 contains the route 2000::4/128. ✅ (True)

R1 is a Level-1-2 router in the same area (49.0001) as R4, so it receives both the summarized 2000::/64 route and the more specific 2000::4/128 route.

Since R1 is directly connected to R4, it can still learn the 2000::4/128 route.

✅ Statement A is true.

B. The routing table of R3 contains the route 2000::/64. ✅ (True)

R3 is a Level-1-2 router, meaning it can receive both Level-1 and Level-2 routes.

Since R4 (a Level-1-2 router) advertises the summarized 2000::/64 route into both levels, R3 will receive 2000::/64 in its routing table.

✅ Statement B is true.

C. The routing table of R2 contains the route 2000::/64. ✅ (True)

R2 is a Level-1-2 router in the same area as R4, meaning it receives the summarized 2000::/64 route.

This is expected behavior since R4 advertises the summary route into both Level-1 and Level-2 areas.

✅ Statement C is true.

D. The routing table of R5 does not contain the route 2000::/64. ❌ (False - Correct Answer)

R5 is a Level-1 router, meaning it can only receive Level-1 routes unless a default route is provided.

Since R3 (a Level-1-2 router) learns 2000::/64, it can propagate it into the Level-1 area (49.0002).

This means R5 will receive the summary route 2000::/64 from R3.

Thus, R5 does contain 2000::/64, making this statement false.

❌ Statement D is false (correct answer).

Final Conclusion:

✅ A. The routing table of R1 contains the route 2000::4/128. (True)✅ B. The routing table of R3 contains the route 2000::/64. (True)✅ C. The routing table of R2 contains the route 2000::/64. (True)❌ D. The routing table of R5 does not contain the route 2000::/64. (False - Correct Answer)

Thus, the correct answer is: D. The routing table of R5 does not contain the route 2000::/64 (False Statement).

Comprehensive and Detailed In-Depth Explanation:

Understanding the BGP Network Topology in the Question:

EBGP Peering & Route Distribution

Each router forms EBGP peer relationships with directly connected neighbors.

BGP learns and propagates routes via EBGP neighbors.

R1 and R4 advertise the static route 192.168.1.0/24 into BGP.

Effect of the aggregate 192.168.1.0/16 detail-suppressed Command on R2

R2 performs BGP route aggregation, summarizing 192.168.1.0/24 into a larger 192.168.1.0/16 route.

The detail-suppressed option hides the more specific 192.168.1.0/24 prefix when advertising routes.

As a result, R2 does not advertise the specific 192.168.1.0/24 route to its neighbors.

Route Selection and Traffic Flow Analysis:

R1 and R4 originate 192.168.1.0/24 and advertise it via BGP.

R2 does not advertise the 192.168.1.0/24 route because of the detail-suppressed command.

R3 cannot learn the specific route from R2, so it must choose an alternative path via R5.

R5 learns 192.168.1.0/24 from R1 and advertises it to R3.

Thus, the best available path for R3 to reach 192.168.1.0/24 is R3 → R5 → R1.

✅ Correct Path: R3 → R5 → R1

Checking Each Option:

✅ Option A: R3 → R5 → R1 (Correct)

R3 learns 192.168.1.0/24 from R5, and R5 forwards traffic to R1, which has the static route.

❌ Option B: R3 → R2 → R1 (Incorrect)

R2 does not advertise 192.168.1.0/24 due to route summarization (detail-suppressed), so R3 cannot use R2 as the next hop.

❌ Option C: R3 → R6 → R5 → R1 (Incorrect)

This is an unnecessary detour.

R3 has a direct EBGP connection with R5, so it will use the shortest path (R3 → R5 → R1) instead of going through R6.

❌ Option D: R3 → R5 → R4 (Incorrect)

R3 prefers the shortest AS path to reach 192.168.1.0/24.

Since R1 and R4 both advertise the route, R3 will prefer the route via R5 to R1 rather than R4.

Final Conclusion:

✅ A. The correct path for traffic from R3 to 192.168.1.0/24 is R3 → R5 → R1.

Thus, the correct answer is: A.

Comprehensive and Detailed In-Depth Explanation:

Understanding the BGP and IS-IS Network Topology in the Question:

IS-IS Areas:

Area 49.0001 (Level-1 IS-IS): Contains R1, R2, R4, R5.

Area 49.0002 (Level-2 IS-IS): Contains R3, R6.

R2 acts as an ABR (Area Border Router) and redistributes routes between Level-1 and Level-2 using import-route isis level-2 into level-1.

BGP Route Reflection & Peering:

R2 and R5 are Route Reflectors (RRs).

iBGP peering is established among all routers (R1, R2, R3, R4, R5, R6).

R1 and R4 import 192.168.1.0/24 into BGP, meaning this prefix will be advertised to all iBGP peers.

R3 and R6 import 192.168.2.0/24 into BGP, meaning this prefix will also be advertised to all iBGP peers.

Route Distribution Analysis:

A. The route 192.168.2.0/24 in the routing table of R4 has two next hops. ✅ (Correct)

R3 and R6 import 192.168.2.0/24 into BGP.

R2 and R5 (Route Reflectors) learn this route and reflect it to their clients (R1, R3, R4, R6).

R4 receives two valid paths to 192.168.2.0/24 via R2 and R5 (both iBGP peers).

Since both routes have the same BGP attributes and cost, they are installed as equal-cost paths in R4's routing table.

✅ Statement A is correct: The routing table of R4 has two next hops for 192.168.2.0/24.

B. The routing table of R1 contains two equal-cost default routes. ❌ (Incorrect)

In an IS-IS Level-1-2 setup, default routes are usually provided to Level-1 routers from an ABR (like R2).

However, the question does not mention that R1 is receiving two default routes or that it is in an equal-cost multipath (ECMP) scenario.

R1 may have only one default route, depending on route preference and cost.

❌ Statement B is incorrect: The routing table of R1 does not necessarily contain two equal-cost default routes.

C. The routing table of R4 contains two equal-cost default routes. ❌ (Incorrect)

Similar to R1, R4 is also a Level-1 router in IS-IS.

If R4 were receiving default routes from multiple ABRs (R2 and R5), then it could have equal-cost paths.

However, there is no indication that R4 is receiving two default routes in this scenario.

❌ Statement C is incorrect: The routing table of R4 does not necessarily contain two equal-cost default routes.

D. The routing table of R1 contains the route 192.168.2.0/24. ✅ (Correct)

R3 and R6 import 192.168.2.0/24 into BGP.

R2 and R5 (Route Reflectors) reflect this route to their iBGP peers, including R1.

Since R1 is an iBGP client of R2 and R5, it will receive 192.168.2.0/24 and install it in its routing table.

✅ Statement D is correct: The routing table of R1 contains the route 192.168.2.0/24.

Final Conclusion:

✅ A. The route 192.168.2.0/24 in the routing table of R4 has two next hops.❌ B. The routing table of R1 does not necessarily contain two equal-cost default routes.❌ C. The routing table of R4 does not necessarily contain two equal-cost default routes.✅ D. The routing table of R1 contains the route 192.168.2.0/24.

Thus, the correct answers are: A, D.

Comprehensive and Detailed In-Depth Explanation:

1. Understanding DHCP Snooping

DHCP Snooping is a security feature that filters untrusted DHCP messages to prevent attacks such as:

Rogue DHCP servers distributing incorrect IP addresses.

DHCP starvation attacks.

In DHCP Snooping, switch ports are classified as:

Trusted Interfaces: Allow both DHCP requests and DHCP responses to pass through.

Untrusted Interfaces: Allow only DHCP requests but drop DHCP responses (to prevent rogue DHCP servers).

2. Analyzing Each Answer Option

Option A: "When receiving a DHCP response packet on GE0/0/2, the switch forwards the packet through GE0/0/1."

Correct.

GE0/0/2 is a trusted interface (connected to the DHCP server).

DHCP responses (ACK, NAK, OFFER) come from the DHCP Server.

Since DHCP responses are allowed on trusted interfaces, the switch forwards them to the client (PC1) via GE0/0/1.

Option B: "When receiving a DHCP request packet on GE0/0/2, the switch forwards the packet through GE0/0/3."

Incorrect.

DHCP requests originate from clients (PC1, attackers, etc.), not from the DHCP server.

The DHCP request should be forwarded to the DHCP server via a trusted interface (not GE0/0/3, which is untrusted).

Option C: "When receiving a DHCP response packet on GE0/0/3, the switch forwards the packet through GE0/0/1."

Incorrect.

GE0/0/3 is an untrusted interface (connected to the attacker).

DHCP responses (ACK, OFFER) from untrusted interfaces are dropped to prevent rogue DHCP attacks.

The switch will not forward the packet.

Option D: "When receiving a DHCP request packet on GE0/0/3, the switch forwards the packet through GE0/0/2."

Correct.

DHCP requests originate from clients (PC1 or attacker).

Since DHCP requests are allowed on untrusted interfaces, the switch forwards them to the DHCP server via the trusted interface (GE0/0/2).

Final Answer:

✅ A and D are correct.

HCIP-Datacom-Advanced Routing & Switching Technology References:

DHCP Snooping and Port Trust Classification

How Trusted and Untrusted Ports Handle DHCP Packets

Preventing Rogue DHCP Servers Using DHCP Snooping

Comprehensive and Detailed In-Depth Explanation:

The Link Layer Discovery Protocol (LLDP) is used for discovering neighboring devices. The given LLDP output contains key details about the neighboring device (R2), including its system name, interface, and management IP address. Let's analyze each option carefully:

Option A: "The sysname of the peer device is R2." ✅ Correct

The output clearly shows System name: R2, which confirms that the neighbor's system name is indeed R2.

Option B: "The interface number of the peer device is GE0/0/0." ✅ Correct

The Port ID in the LLDP output is GE0/0/0, which matches the statement in Option B.

Option C: "The VLAN ID of the peer device is 1." ❌ Incorrect

The given LLDP output does not mention any VLAN ID information. Therefore, this option is false.

Option D: "The management IP address of the peer device is 192.168.1.1." ✅ Correct

The Management address field in the LLDP output confirms the IP address as 192.168.1.1, making this statement true.

HCIP-Datacom-Advanced Routing & Switching Technology References:

Huawei HCIP-Datacom Official Certification Guide, Chapter on LLDP and Network Device Discovery.

HCIA/HCIP Datacom Training Materials – LLDP Neighbor Discovery Commands.

Huawei Datacom Configuration Guide – Section on display lldp neighbor interface.

Comprehensive and Detailed In-Depth Explanation:

1. Understanding Site of Origin (SoO) in MPLS VPNs

SoO (Site of Origin) is used in MPLS VPNs to prevent loops in multi-homed CE scenarios.

Routes with the same SoO value are not advertised back to the same site.

2. Analysis of Each Answer Choice

A. "To enable CE3 to receive the route, run the command peer 10.1.1.1 soo 200:1 on PE1." (❌ False)

SoO is used to prevent loops by tagging routes that belong to the same site.

Applying SoO (200:1) on PE1 for CE1 means that any other PE (such as PE2) receiving the route will not advertise it back to the same site (CE1).

This statement is false because applying SoO here does not directly enable CE3 to receive the route. Instead, CE3 must accept routes with SoO values properly configured.

B. "If the commands peer 10.1.1.1 soo 200:1 and peer 10.1.2.1 soo 200:1 are run on PE1, CE2 accepts the route." (❌ False)

SoO ensures that a route received from one CE is not sent back to another CE in the same site.

If SoO (200:1) is assigned to CE1 and CE2, routes will be blocked because they share the same SoO tag.

Thus, CE2 will not accept the route, making this statement false.

C. "If the command peer 10.1.3.1 substitute-as is run on PE2, CE3 accepts the route." (✅ True)

substitute-as allows a router to replace the received AS number in the AS_PATH with another AS number, ensuring that routes are accepted even when AS_PATH filtering is in place.

This prevents CE3 from rejecting the route due to AS-Path loop prevention.

✅ Thus, this statement is true.

D. "If no additional action is taken, CE3 discards the route." (✅ True)

By default, CE3 will discard the route because of BGP loop prevention (same AS in the AS_PATH).

To allow CE3 to receive the route, the allowas-in or substitute-as command must be configured on PE2.

✅ Thus, this statement is true.

3. Evaluating the Answer Choices

Option

Correct?

Reasoning

A

❌ False

Applying SoO does not directly enable CE3 to receive the route.

B

❌ False

If both CE1 and CE2 have the same SoO value, CE2 will reject the route.

C

✅ True

Substitute-AS allows CE3 to accept the route by modifying the AS-Path.

D

✅ True

Without additional configuration, CE3 will discard the route due to AS-Path loop prevention.

✅ Correct Answer: A and B are false.

Final Conclusion:

SoO prevents routing loops in MPLS VPN multi-homing.

CE2 will reject the route if it has the same SoO as CE1.

CE3 requires the substitute-as or allowas-in command to accept the route.

Thus, statements A and B are false.

1. Understanding Router-LSAs in OSPFv3

Router-LSA (Type 1 LSA) is generated by every OSPFv3 router to describe its own links and connected networks within the same area.

Each router in an OSPF area generates exactly one Router-LSA to advertise its own topology information.

Router-LSAs are flooded throughout the area but do not cross area boundaries.

2. Analyzing the Given OSPFv3 Network

The topology consists of three routers: R1, R2, and R3, all connected in OSPFv3 Area 0.

Since all three routers participate in OSPFv3, each router generates its own Router-LSA (Type 1 LSA).

R2, as an OSPF router, will have its own Router-LSA and also receive the Router-LSAs from R1 and R3.

3. Counting the Number of Router-LSAs in R2’s LSDB

R1 generates 1 Router-LSA (for itself).

R2 generates 1 Router-LSA (for itself).

R3 generates 1 Router-LSA (for itself).

Total Router-LSAs in R2’s LSDB = 3 (one from each router).

Final Answer:

Answer: 3

HCIP-Datacom-Advanced Routing & Switching Technology References:

OSPFv3 LSA Types and Their Roles

Understanding Router-LSA (Type 1) and Its Function in LSDB

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

Comprehensive and Detailed In-Depth Explanation:

To verify the correct answer, we need to analyze Bidirectional Forwarding Detection (BFD) behavior and the provided configuration.

1. Understanding BFD Configuration Parameters

BFD (Bidirectional Forwarding Detection) is a protocol used for fast failure detection between directly connected devices.

Key Configuration Parameters in BFD:

Peer IP (bind peer-ip)

This specifies the destination router’s IP address for the BFD session.

✅ Correctly configured on both R1 and R2.

Discriminator Local/Remote (discriminator local X / remote Y)

These values must match between the two routers.

✅ Correctly configured (R1: local 1, remote 2; R2: local 2, remote 1).

Min-TX Interval (min-tx-interval)

Defines the minimum transmit interval for BFD packets.

❌ Missing from R2’s configuration (could be a cause for mismatch).

Min-RX Interval (min-rx-interval)

Defines the minimum receive interval for BFD packets.

❌ Missing from R2’s configuration (could be a cause for mismatch).

2. Analyzing the Configuration on R1 and R2

✅ Configuration on R1 (Correct)

shell

CopyEdit

bfd tor2 bind peer-ip 10.0.12.2

discriminator local 1

discriminator remote 2

min-tx-interval 1500

min-rx-interval 1500

This configuration is correct.

❌ Configuration on R2 (Incomplete)

shell

CopyEdit

bfd tor1 bind peer-ip 10.0.12.1

discriminator local 2

discriminator remote 1

Missing min-tx-interval and min-rx-interval.

3. Why the Answer is FALSE?

A BFD session does NOT go down due to mismatched timing parameters.

BFD dynamically negotiates timing values, meaning even if R2 is missing min-tx/min-rx values, the session should still establish.

However, the session will fail if the peer IP or discriminator values are incorrect (which they are NOT in this case).

The actual cause of failure in this case is likely the missing min-tx and min-rx settings on R2, NOT a mismatch between R1 and R2.