Pass the Huawei HCIP-Datacom H12-831_V1.0 Questions and answers with Dumpstech

Comprehensive and Detailed In-Depth Explanation:

Understanding DHCP Snooping and Trusted/Untrusted Ports

1. What is DHCP Snooping?

DHCP Snooping is a security feature that prevents rogue DHCP servers from providing unauthorized IP configurations to clients.

It categorizes switch ports into:

Trusted Ports: Allow DHCP Offer and ACK messages from a legitimate DHCP server.

Untrusted Ports: Block unauthorized DHCP responses to prevent rogue DHCP attacks.

Analyzing the Network Setup in the Figure

Interface

Connected Device

DHCP Role

Should it be Trusted?

GE0/0/1

PC1 (DHCP Client)

Requests DHCP leases

❌ Untrusted

GE0/0/2

DHCP Server (Legitimate)

Provides DHCP leases

✅ Trusted

GE0/0/3

Web Server

Not involved in DHCP

❌ Untrusted

GE0/0/4

Bogus (Rogue) DHCP Server

Malicious DHCP Server

❌ Untrusted & Blocked

GE0/0/2 is connected to the legitimate DHCP server, meaning it should be marked as a TRUSTED interface.

GE0/0/4 connects to a bogus DHCP server, which must be UNTRUSTED to block unauthorized DHCP responses.

GE0/0/1 (Client) and GE0/0/3 (Web Server) do not need to be trusted.

✅ Thus, the correct answer is: D. GE0/0/2.

Final Conclusion:

✅ GE0/0/2 should be configured as the trusted DHCP interface.

❌ GE0/0/1 (Client) should remain untrusted.

❌ GE0/0/3 (Web Server) does not need DHCP trust.

❌ GE0/0/4 (Bogus DHCP Server) should be blocked.

Thus, the correct answer is: D. GE0/0/2.

PIM Sparse Mode (PIM-SM) elects a Designated Router (DR) on a shared network segment to coordinate multicast source registration and receiver-side multicast forwarding.

The election first compares the DR priorities advertised in PIM Hello messages.

The router with the highest DR priority is selected. When routers have equal priorities, the router with the numerically highest interface IP address wins.

In the topology, R1 uses 10.0.12.1/24 and R2 uses 10.0.12.2/24. Both routers use default DR priority values.

Because 10.0.12.2 is higher than 10.0.12.1, R2 is elected as the PIM-SM Designated Router.

This differs from the IGMPv2 querier election, which selects the router with the lowest IP address. Thus, R1 would be the IGMP querier, but R2 is the PIM-SM DR.

This IS-IS network includes:

R1 as a Level-1 router (area-internal only)

R2 as a Level-1-2 router (acts as a border between L1 and L2)

R3 as a Level-2 router (external to area 49.0001)

The command on R1:

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default-route-advertise always level-1

means R1 advertises a default route (0.0.0.0/0) to other Level-1 routers. This helps L1 routers like R1 route toward unknown destinations via R2.

Now analyzing each option:

✅ Option A: 10.0.2.2 can ping 10.0.3.3✔ CorrectR2 is Level-1-2 and has a Level-2 adjacency to R3. So R2 (10.0.2.2) can reach R3’s loopback (10.0.3.3).

✅ Option B: 10.0.12.2 can ping 10.0.3.3✔ Correct10.0.12.2 is on R2, and R2 has full visibility of R3 through Level-2. Thus, it can route traffic to 10.0.3.3.

❌ Option C: 10.0.1.1 can ping 10.0.3.3✖ IncorrectR1 is Level-1 only and cannot see Level-2-only destinations like 10.0.3.3. There is no route leaking from R2’s L2 database into the L1 area.

✅ Option D: 10.0.1.1 can ping 10.0.2.2✔ CorrectBoth are in the Level-1 area (49.0001). The IS-IS Level-1 adjacency allows reachability between these loopbacks.

✅ Official Huawei Extract:

" In IS-IS, Level-1 routers cannot learn Level-2-only routes unless route leaking is configured. A Level-1-2 router like R2 can route between L1 and L2 domains. The command default-route-advertise always level-1 causes R2 to advertise a default route into the Level-1 area, enabling R1 to forward unknown destinations. However, L1 routers still cannot reach L2-only loopbacks like R3’s unless route leaking is explicitly configured. "

— [Huawei HCIA-Datacom Certification Guide – Chapter: IS-IS Route Types and Default Route Advertisement]

The statement is false due to a contradiction.

Sticky MAC addresses are not aged out automatically. Once a MAC address is converted to sticky, it is bound to the port and does not age out like dynamic MAC addresses unless manually cleared or the configuration is removed.

If the goal is to allow MAC entries to age out when users change frequently, dynamic MAC addresses (not sticky) should be used.

✅ Official Reference from Huawei:

" Sticky MAC addresses are retained across restarts and do not age out. To allow MAC addresses to time out and be relearned, do not use sticky configuration. "

— [Huawei HCIA-Datacom Certification Guide – Port Security Section]

MP-BGP (Multiprotocol BGP) is an extension of BGP that supports multiple address families, including VPNv4 routes.

MP-BGP introduces a new BGP path attribute called MP_REACH_NLRI (for route advertisement) and MP_UNREACH_NLRI (for route withdrawal).

These attributes are used for:

Advertising VPNv4 and VPNv6 routes

Withdrawing unreachable VPNv4/VPNv6 routes

Supporting other AFI/SAFI combinations beyond IPv4 unicast

✅ Official Reference from Huawei:

" MP-BGP introduces MP_REACH_NLRI and MP_UNREACH_NLRI attributes to advertise or withdraw VPNv4/VPNv6 routes. "

— [Huawei HCIA-Datacom Certification Guide – BGP/MPLS VPN Section]

???? BGP Peer Configuration Recap:

R1:

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bgp 100

router-id 10.0.1.22

peer 10.0.12.2 as-number 200

R2:

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bgp 200

router-id 10.0.2.1

peer 10.0.12.1 as-number 100

✅ The BGP peer relationship is being configured over directly connected IPs:

R1 uses 10.0.12.1

R2 uses 10.0.12.2

???? Is the problem caused by inconsistent router IDs?

NO. BGP does not require matching router IDs. Router IDs only need to be unique.

In fact, it ' s normal for router IDs to be different, especially in EBGP.

???? Is the problem caused by interface IP mismatch?

NO. The interface IPs are used correctly:

R1 peers with 10.0.12.2 (R2’s interface)

R2 peers with 10.0.12.1 (R1’s interface)

They are directly connected

???? Conclusion:

There is no issue with router IDs or IPs. The cause of the EBGP peer failure is not due to those fields, so the statement in the question is false.

✅ Final Answer: B. FALSE

Official Huawei Extract:

" BGP router IDs must be unique but do not need to match between peers. For EBGP over directly connected interfaces, the peer IPs must be correct, but differences in router IDs are acceptable. "

— [Huawei HCIA-Datacom Guide – BGP Peer Establishment and Troubleshooting]