H12-831_V1.0 Exam Dumps - HCIP-Datacom-Advanced Routing & Switching Technology V1.0

Comprehensive and Detailed In-Depth Explanation:

Step 1: Understanding OSPF Areas and Summarization

Loopback0 on R5 has IP 10.0.5.5/32 and is advertised into OSPF.

The abr-summary 10.0.5.0 255.255.255.0 command is applied in area 2 on R1, which means:

Instead of advertising individual host routes (like 10.0.5.5/32), R1 advertises the summarized route 10.0.5.0/24 into Area 0 (Backbone).

This summarized route is then propagated into other areas via Area 0 (Backbone).

Step 2: Analyzing the Routing Table of Each Router

R5 (Originating Router in Area 2)

R5 only knows 10.0.5.5/32 because it's the originating router.

The abr-summary command does not affect R5 itself.

❌ R5 does not have 10.0.5.0/24.

R1 (ABR for Area 2, Summarizing the Route)

R1 creates and advertises 10.0.5.0/24 into Area 0.

This summary route is sent to other areas via Area 0.

R2 (Connected to Area 0 & Area 1)

Since R2 is part of Area 0 (Backbone), it receives 10.0.5.0/24 from R1.

✅ R2 has 10.0.5.0/24 in its routing table.

R3 (Connected to Area 0 & Area 2)

Since R3 is also connected to Area 0, it receives the summary route 10.0.5.0/24 from R1.

✅ R3 has 10.0.5.0/24 in its routing table.

R4 (In Area 1, which is not directly connected to Area 2)

R4 belongs to Area 1, and unless explicitly advertised through inter-area summarization, it will not have 10.0.5.0/24.

Since no specific mention of summary advertisement into Area 1 is made, R4 does not get 10.0.5.0/24.

❌ R4 does not have 10.0.5.0/24.

Final Answer: ✅ R2, R3 (Option B, C)

References:

HCIP-Datacom-Advanced Routing & Switching Technology V1.0 – OSPF Route Summarization

OSPF Inter-Area Route Advertisement via ABRs

OSPF Backbone (Area 0) Behavior and Route Distribution

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.

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): R1, R2, R4, R5.

Area 49.0002 (Level-2 IS-IS): 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:

Route to 192.168.1.0/24 (Imported by R1 & R4):

R1 and R4 advertise 192.168.1.0/24 into iBGP.

Since R2 and R5 are Route Reflectors (RRs), they will reflect these routes to all their iBGP clients (R1, R3, R4, R6).

R2 learns two valid routes to 192.168.1.0/24 (from R1 and R4).

R5, as another RR, learns both routes and advertises them as well.

R2 ultimately has three valid paths (direct from R1 and R4, plus a reflected route from R5).✅ Statement C is correct: The BGP routing table of R2 contains three valid routes to 192.168.1.0/24.

R5 also learns 192.168.1.0/24 from both R1 and R4.✅ Statement B is correct: The BGP routing table of R5 contains two valid routes to 192.168.1.0/24 (from R1 and R4).

Route to 192.168.2.0/24 (Imported by R3 & R6):

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 three valid paths (directly from R3 and R6 via BGP, and one additional reflected path via R5).✅ Statement D is correct: The BGP routing table of R4 contains three valid routes to 192.168.2.0/24.

Checking Statement A:

R3 originally imports 192.168.2.0/24 and advertises it.

Since it is a Route Reflector Client of R5 and R2, it should have multiple routes via iBGP, not just one.❌ Statement A is incorrect because R3 should have multiple valid routes, not just one.

Final Conclusion:

✅ B. The BGP routing table of R5 contains two valid routes to 192.168.1.0/24.✅ C. The BGP routing table of R2 contains three valid routes to 192.168.1.0/24.✅ D. The BGP routing table of R4 contains three valid routes to 192.168.2.0/24.❌ A. The BGP routing table of R3 does NOT contain only one valid route to 192.168.2.0/24 (it has multiple routes).

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

Comprehensive and Detailed In-Depth Explanation:

The clock timezone command only affects the displayed time on the device and does not impact routing protocol operations.

Dynamic routing protocols such as OSPF, IS-IS, BGP, and EIGRP rely on timers, authentication, and correct network configurations, but they do not require the same time zone settings.

Potential issues with different time zones:✅ Log timestamps may be inconsistent, making troubleshooting harder.✅ Time-sensitive features like NTP synchronization might be affected.❌ But different time zones will not prevent dynamic routing neighbor relationships.

📖 Reference: HCIP-Datacom Advanced Routing & Switching Technology – System Time Configuration & Routing Protocols

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 the IS-IS Network Structure in the Question:

IS-IS Area IDs and Router Roles

Area 49.0001 (Level-1-2): Contains R1, R2, R4 (all Level-1-2 routers).

Area 49.0002 (Level-1-2 & Level-1): Contains R3 (Level-1-2) and R5 (Level-1 only).

Key Command Used: ipv6 default-route-advertise always level-1

This command forces R4 to advertise a default route (::/0) to all Level-1 routers within its area.

Only Level-1 routers in the same area as R4 will receive the default route.

Level-2 routers do not receive or propagate this default route unless additional configuration is done.

Route Distribution Analysis:

R4 (Level-1-2) is configured to advertise a default route to Level-1 routers.

R1 and R2 (both Level-1-2) are in the same area (49.0001) as R4, so they receive the default route.

R3 (Level-1-2) is in area 49.0002 but connects to R4 (49.0001), meaning it can receive the default route through its Level-1 connection.

R5 (Level-1 only) is in area 49.0002, but R4 does not propagate the default route to another Level-1 area (49.0002).

Since R5 is a Level-1 router and does not have a Level-2 connection, it cannot receive the default route from R4.

Final Conclusion:

✅ R1 receives the default route.✅ R2 receives the default route.✅ R3 receives the default route.❌ R5 does NOT receive the default route.

Thus, the correct answer is: C. R5.