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

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:

Understanding Port Isolation in the Network

Network Setup Details:

The switch is Layer 3, with VLANIF10 configured as 10.1.1.1/24 (gateway for all PCs).

All PCs are in VLAN 10 and use 10.1.1.1 as the default gateway.

Port isolation is enabled on switch interfaces, dividing them into two groups:

Group 1 (PC1 & PC2): GigabitEthernet0/0/1 and GigabitEthernet0/0/2

Group 2 (PC3 & PC4): GigabitEthernet0/0/3 and GigabitEthernet0/0/4

Port Isolation Behavior:

Ports within the same isolation group CAN communicate with each other.

Ports from different isolation groups CANNOT communicate directly.

All devices CAN still communicate with the L3 switch (10.1.1.1), which acts as the gateway.

Ping Analysis from PC1 (10.1.1.2)

Destination IP

Device

Connected Port

Isolation Group

Ping Result from PC1

10.1.1.3

PC2

GigabitEthernet0/0/2

Group 1

✅ Can Ping

10.1.1.4

PC3

GigabitEthernet0/0/3

Group 2

❌ Cannot Ping

10.1.1.5

PC4

GigabitEthernet0/0/4

Group 2

❌ Cannot Ping

10.1.1.1

L3 Switch (Gateway)

N/A

Not Isolated

✅ Can Ping

Which IPs Cannot be Pinged from PC1?

PC3 (10.1.1.4) and PC4 (10.1.1.5) are in a different isolation group (Group 2), so PC1 cannot reach them directly.

PC2 (10.1.1.3) is in the same isolation group (Group 1), so PC1 can ping it.

PC1 can ping the gateway (10.1.1.1) because the switch is Layer 3 and forwards traffic.

Thus, the correct answers are: A. 10.1.1.3 and D. 10.1.1.4.

Final Conclusion:

✅ PC1 CAN ping:

10.1.1.3 (PC2, same isolation group)

10.1.1.1 (Gateway, L3 Switch)

❌ PC1 CANNOT ping:

10.1.1.4 (PC3, different isolation group)

10.1.1.5 (PC4, different isolation group)

Thus, the correct answer is: A. 10.1.1.3 and D. 10.1.1.4.