Free Practice Questions for Huawei H12-831_V1.0 Exam

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.

Understanding VLAN Aggregation (Super-VLAN and Sub-VLANs)

VLAN aggregation allows multiple sub-VLANs to be grouped under a super-VLAN, reducing the number of VLANIF interfaces required for IP address configuration.

Super-VLAN: A logical VLAN that does not forward Layer 2 traffic directly but is used for Layer 3 communication.

Sub-VLANs: VLANs that exist within the Super-VLAN but cannot communicate with each other by default.

2️⃣ Why is the " inter-sub-vlan-proxy enable " Command Needed?

By default, hosts in different sub-VLANs under the same super-VLAN cannot communicate with each other because sub-VLANs do not exchange MAC address information.

The inter-sub-vlan-proxy enable command allows Layer 3 communication between sub-VLANs under the same super-VLAN by acting as a proxy for ARP requests and replies.

This enables inter-sub-VLAN communication while still reducing the number of VLANIF interfaces required.

3️⃣ Command Syntax and Execution

The correct command should be run under the VLANIF interface of the super-VLAN:

[Switch] interface vlanif 10

[Switch-Vlanif10] inter-sub-vlan-proxy enable

Selective QinQ is used to add outer VLAN tags to customer (inner-tagged) packets, enabling service identification and isolation in carrier networks.

✅ B – Supported: You can match on inner VLAN IDs to apply different outer VLAN tags.

✅ C – Supported: 802.1p priorities (inner VLAN CoS values) can be used as match criteria.

✅ D – Supported: You can apply QinQ behavior based on QoS policies using traffic classification.

❌ A is false – Selective QinQ does not use TTL (Time To Live) as a matching criterion. TTL is an IP-layer field and not used in L2 QinQ configurations.

✅ Official Reference from Huawei:

" Selective QinQ allows different outer VLAN tags to be added based on inner VLAN IDs, 802.1p priorities, and QoS policy rules. TTL values are not used as matching conditions. "

— [Huawei HCIA-Datacom Certification Guide – VLAN and QinQ Chapter]

OSPF uses the Shortest Path First (SPF) algorithm to calculate a Shortest Path Tree (SPT) from information maintained in its Link-State Database (LSDB). Each router places itself at the root of this tree and determines optimal forwarding paths.

The first part of the statement is correct. However, configuring the maximum interval for SPF calculation to 0 milliseconds is not supported by the specified Huawei intelligent-timer parameters.

Huawei provides the spf-schedule-interval command to control SPF calculation frequency. The intelligent timer uses maximum, initial, and hold intervals to balance rapid convergence against excessive processing.

The maximum interval has a minimum permitted value of 1 millisecond, not 0. Furthermore, repeatedly triggering SPF calculations during topology instability can increase CPU utilization.

Therefore, the statement is FALSE because its proposed timer configuration is invalid.

HCIP-Datacom-Advanced Routing & Switching Technology V1.0 Training Material.pdf

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The display mpls lsp output on R1 contains the following entry for FEC 3.3.3.3/32:

In/Out Label: NULL/1025

Out Interface: GE0/0/1

NULL/1025 means R1 is the ingress LSR for this LSP. The packet initially has no label, so R1 performs a push operation and sends it toward R2 with label 1025.

R2’s corresponding entry is:

In/Out Label: 1025/3

Out Interface: GE0/0/1

Label value 3 is the MPLS implicit-null label. It is not placed in the outgoing packet. Instead, it instructs the penultimate-hop router—R2—to remove label 1025. This operation is called penultimate-hop popping (PHP). R2 consequently sends an unlabeled IPv4 packet to egress router R3, which processes the packet using normal IP forwarding.

Therefore, the packet sent from R1 carries label 1025, and R2 removes the label before forwarding it toward R3. Huawei MPLS label operations and PHP

OSPF uses Type 7 Link-State Advertisements (LSAs) to describe external routing information originating within a Not-So-Stubby Area (NSSA). An ASBR inside an NSSA can redistribute external routes and advertise them using Type 7 LSAs.

However, Type 7 LSAs have area-local flooding scope. They are distributed only throughout the NSSA in which they originate, not throughout all NSSAs or ordinary OSPF areas.

An NSSA Area Border Router (ABR) can translate eligible Type 7 LSAs into Type 5 AS-External LSAs. These Type 5 LSAs can then be advertised throughout the appropriate non-stub portions of the OSPF autonomous system.

Stub areas do not accept Type 5 external LSAs, and Type 7 LSAs are not flooded into other areas.

Consequently, the statement incorrectly describes the flooding scope of Type 7 LSAs and is FALSE.

HCIP-Datacom-Advanced Routing & Switching Technology V1.0 Training Material.pdf

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OSPFv3 operates over IPv6 and uses the IPv6 header directly. It can transmit packets in the following modes:

Multicast: Uses standard multicast addresses such as:

FF02::5 (All OSPF routers)

FF02::6 (All DR/BDR routers)

Unicast: Used for point-to-point neighbor communication when required.

Broadcast: On broadcast-capable networks, such as Ethernet.

✅ Official Reference from Huawei:

" OSPFv3 runs directly on top of IPv6 and uses the IPv6 header for transport. It supports unicast, multicast, and broadcast modes, similar to OSPFv2 but adapted for IPv6. "

— [Huawei HCIA-Datacom Certification Guide – OSPFv3 Fundamentals]