Free Practice Questions for the Huawei Certification H19-402_V1.0 Exam (2026 Updated)

In Huawei data center networking, especially within Intelligent Lossless Data Center Network design, incast traffic is a well-known challenge in distributed systems such as AI computing clusters and distributed storage architectures .

In an incast scenario , a large number of servers simultaneously send traffic to a single destination (e.g., parameter server in AI training or storage node in distributed storage). This sudden aggregation of traffic can quickly overflow switch buffers , leading to packet loss, increased latency, and throughput degradation .

Huawei identifies incast as a primary cause of network congestion in modern data centers. To mitigate this, CloudFabric solutions implement advanced congestion control technologies such as:

PFC (Priority Flow Control) to prevent packet loss

ECN (Explicit Congestion Notification) for early congestion signaling

AI-driven traffic scheduling and load balancing

These mechanisms help build a lossless Ethernet fabric , which is essential for RDMA-based AI workloads and high-performance storage systems.

Therefore, the statement is TRUE , as incast traffic is indeed prone to causing congestion in such environments.

In Huawei CloudFabric architecture, the underlay network is the physical IP fabric, while the overlay network is a logical network built on top of it using technologies like VXLAN and BGP EVPN .

Option A is false because the overlay network does not require bare optical fibers . It operates independently of the physical medium and can run over any IP-based underlay (Ethernet, optical, etc.). The overlay abstracts the physical infrastructure.

Option B is correct : the underlay network is transparent to endpoints (servers, firewalls, routers). These devices only interact with the overlay and are unaware of the underlying transport.

Option C is correct : the overlay has its own forwarding plane (VXLAN encapsulation) and control plane (BGP EVPN) , enabling scalable and automated network virtualization.

Option D is correct : the overlay is a logical network built over the underlay , providing tenant isolation and flexible service deployment.

Huawei best practices emphasize decoupling overlay from underlay , ensuring flexibility, scalability, and simplified operations.

Therefore, the correct answer is A .

In Huawei CloudFabric Solution, health check and intelligent O & M are performed across multiple key dimensions to ensure stable, secure, and efficient network operations. These dimensions provide a comprehensive view of the data center network’s health.

Capacity (A): Evaluates resource utilization such as bandwidth, device capacity, and scalability limits to prevent bottlenecks.

Status (B): Monitors the operational state of devices, links, and services (up/down, faults, alarms).

Connectivity (D): Verifies end-to-end network reachability, ensuring that services and tenants can communicate properly across the fabric.

Security policy (E): Checks correctness and consistency of policies such as ACLs, segmentation, and service chaining rules.

Performance (F): Measures latency, packet loss, throughput, and congestion, which are critical in modern workloads like AI and storage.

VM (C) is not considered a core health check dimension at the network level. It belongs more to the compute/virtualization domain rather than network O & M.

Huawei iMaster NCE-FabricInsight uses these dimensions to provide proactive fault detection, root cause analysis, and optimization recommendations , ensuring intelligent lifecycle management of the data center network.

In Huawei CloudFabric and VXLAN-based overlay networking, the overlay provides abstraction, flexibility, and scalability by decoupling logical services from the physical infrastructure. NVEs (Network Virtualization Edge nodes) can indeed be deployed on physical switches (such as leaf switches), which is a fundamental capability of hardware-based VXLAN fabrics. Additionally, overlay networks are designed to meet the needs of private cloud environments, offering high performance, simplified O & M, and enhanced security through network segmentation (e.g., VXLAN VNIs).

Overlay networks also support access for both virtual machines and physical servers, ensuring consistent connectivity regardless of workload type.

However, statement D is incorrect. In Huawei’s architecture, especially with BGP EVPN-based VXLAN, the control plane is distributed rather than relying on a controller to synchronously deliver flow tables. Devices dynamically learn and exchange forwarding information using EVPN. Even in SDN-based scenarios with iMaster NCE-Fabric, policy delivery is not strictly synchronous flow table pushing in the traditional sense (like OpenFlow).

Therefore, “controller delivers flow tables synchronously” is not a standard capability of Huawei overlay networks, making option D incorrect.

In OpenStack Neutron, the core network abstraction models are Network, Subnet, and Port , which align with Huawei CloudFabric’s logical network design principles. A Network represents a Layer 2 broadcast domain, similar to a VXLAN segment (VNI) in Huawei data center fabrics. It provides tenant-level isolation and forms the foundation for overlay networking.

A Subnet defines the Layer 3 IP addressing scheme within a network, including CIDR blocks, gateway addresses, and DHCP configurations. This aligns with Huawei’s underlay/overlay separation, where IP addressing is critical for both service reachability and automation.

A Port is the connection point between a virtual machine (VM) and the virtual network, equivalent to a virtual NIC. It carries MAC/IP bindings and security policies, similar to endpoint definitions in EVPN-based fabrics.

The option vRouter is incorrect because Neutron uses the concept of a Router , not “vRouter,” and it is considered a higher-layer service component rather than a fundamental network model. Huawei documentation consistently emphasizes these three as the foundational constructs for virtualized network design.

In Huawei data center network design, VXLAN overlay deployment models are categorized based on where VTEPs (VXLAN Tunnel End Points) are located. These include host-based overlay, network-based overlay, and hybrid overlay.

In a host overlay , VTEPs are implemented only on vSwitches (such as those within hypervisors), and physical switches only provide IP transport (underlay). In a network overlay , VTEPs are deployed only on physical switches (typically leaf switches), and servers are unaware of VXLAN encapsulation.

The hybrid overlay model combines both approaches. In this design, VTEPs can exist on both vSwitches (inside virtualized hosts) and physical switches (such as leaf devices). This allows greater flexibility, supporting mixed environments where some workloads use hypervisor-based encapsulation while others rely on hardware VTEPs for higher performance or integration with bare-metal servers.

Huawei CloudFabric supports hybrid overlay to enable smooth evolution from traditional to fully virtualized environments. Therefore, the correct answer is Hybrid overlay (C) .

Huawei M-LAG 2.0 is designed to provide ultra-fast convergence and high availability in modern data center networks. One of its key enhancements over traditional M-LAG implementations is the ability to achieve fast fault detection and rapid switchover , minimizing service interruption.

In the event of a single point of failure (such as link or device failure), M-LAG 2.0 leverages mechanisms like BFD (Bidirectional Forwarding Detection) and optimized peer-link synchronization to quickly detect failures and redirect traffic. The switchover time is typically around 5 milliseconds , ensuring near hitless failover for critical services.

This ultra-fast convergence is particularly important for applications such as AI workloads, financial systems, and real-time services , where even small delays can impact performance.

Compared to traditional technologies (which may take tens or hundreds of milliseconds), Huawei M-LAG 2.0 significantly improves network reliability, service continuity, and user experience .

Therefore, the correct answer is C (5 ms) .

In Huawei CloudFabric and VXLAN-based data center designs, it is a best practice to use the IP address of a loopback interface as the VTEP (VXLAN Tunnel End Point) source address instead of a physical interface IP. This recommendation is based on reliability, stability, and operational flexibility.

A loopback interface is always in the UP state as long as the device is operational, whereas physical interfaces may go down due to link failures. If a physical interface IP is used as the VTEP source, any link failure would cause VXLAN tunnels to flap, impacting service continuity. In contrast, loopback interfaces remain reachable through the underlay network via dynamic routing protocols such as OSPF, IS-IS, or BGP, ensuring consistent tunnel endpoints.

Additionally, using loopback addresses supports ECMP (Equal-Cost Multi-Path) forwarding in the underlay, improving load balancing and network utilization. Huawei documentation strongly emphasizes this design principle to enhance VXLAN tunnel resilience and simplify network operations. Therefore, the statement is TRUE.

In Huawei CloudFabric intelligent O & M (Operations and Maintenance), multiple southbound data collection protocols are supported to enable comprehensive monitoring, analysis, and fault diagnosis. Commonly supported protocols include Telemetry, SNMP, NetStream, and ERSPAN .

Telemetry is the primary modern mechanism, providing real-time streaming data with high accuracy and low latency. SNMP is used for traditional device monitoring and alarm collection. NetStream (Huawei’s implementation of NetFlow) is used for traffic analysis, while ERSPAN enables remote traffic mirroring for deep packet inspection and troubleshooting.

However, Qx is not a standard or supported southbound protocol in Huawei CloudFabric O & M architecture. It is not referenced in Huawei documentation as a mechanism for data collection or monitoring.

Therefore, option B is correct because it identifies the protocol that is not supported , while all other options are valid and commonly used in Huawei intelligent O & M solutions.

In Huawei M-LAG design, strict requirements ensure stability and consistency between the two participating devices. Option A is false because M-LAG must be established between devices of the same type and model (or at least fully compatible models) . This ensures consistent forwarding behavior, synchronization of MAC/ARP tables, and proper operation of the peer-link and keepalive mechanisms. Using different device types is not supported and may lead to instability.

Option B is correct : unidirectional isolation is relevant only for dual-homed scenarios. If a device is single-homed, this mechanism is not applied.

Option C is correct : the peer-link is a critical connection between M-LAG peers and is typically configured as an Eth-Trunk (link aggregation) to ensure high bandwidth and redundancy.

Option D is also correct : peer-link interfaces are dedicated and cannot be used for other services, ensuring reliable synchronization and control-plane communication.

Huawei best practices emphasize homogeneous device deployment for M-LAG to guarantee predictable and stable operation.

In Huawei CloudFabric architecture, the underlay network is the physical IP network that provides basic connectivity and routing reachability for overlay services such as VXLAN.

Option A is correct : the underlay acts as the bearer (transport) network for VXLAN traffic, carrying encapsulated packets between VTEPs.

Option B is correct : the underlay includes both NVE (Network Virtualization Edge) devices that perform VXLAN encapsulation/decapsulation and standard IP forwarding devices (e.g., spine switches).

Option C is correct : the underlay has its own independent control plane , typically using IGP (OSPF/IS-IS) or BGP (EBGP) , and operates independently from the overlay (EVPN).

Option D is false because the underlay network is fundamentally responsible for Layer 3 IP reachability between VTEPs. Without proper L3 routing in the underlay, VXLAN tunnels cannot be established.

Huawei best practices emphasize a simple, stable, and highly reliable underlay , as it is the foundation for all overlay services.

Therefore, the correct answer is D .

RDMA (Remote Direct Memory Access) is a key technology in Huawei’s Intelligent Lossless Data Center Network , widely used in high-performance scenarios such as AI training, distributed storage, and HPC.

The statement is correct because RDMA enables direct memory-to-memory data transfer between servers without involving the CPU or operating system in the data path. This bypass mechanism significantly reduces overhead and enables:

Ultra-low latency (microsecond-level communication)

High throughput (efficient use of bandwidth)

Low CPU utilization , freeing compute resources for applications

Although RDMA was originally developed for InfiniBand networks , it is now widely used over Ethernet through technologies like RoCE (RDMA over Converged Ethernet) in Huawei CloudFabric solutions.

To support RDMA effectively, Huawei implements lossless Ethernet mechanisms such as PFC, ECN, and congestion control algorithms to ensure reliable packet delivery.

Therefore, the statement accurately describes RDMA characteristics and is TRUE .

In Huawei’s intelligent O & M architecture, NETCONF is a modern network management protocol designed for transactional, reliable, and concurrent-safe configuration management . One of its key features is the lock mechanism , which allows a user or system to lock a configuration datastore (such as candidate or running configuration) to prevent other users or processes from making conflicting changes simultaneously. This ensures consistency, atomic operations, and rollback capability , which are critical in automated data center environments like CloudFabric.

On the other hand, SNMP (Simple Network Management Protocol) is primarily designed for monitoring and basic configuration , but it lacks advanced transaction control features. SNMP does not support configuration locking or transactional commits, meaning multiple users can overwrite each other’s changes, potentially leading to configuration inconsistencies.

Huawei strongly recommends using NETCONF/YANG-based automation (e.g., via iMaster NCE-Fabric) for modern data center operations because it provides structured data modeling, conflict prevention, and programmability , which SNMP cannot offer.

Therefore, the statement is TRUE .

In Huawei Cloud Stack (HCS) architecture, ManageOne serves as the unified cloud management platform , responsible for end-to-end orchestration, service provisioning, and lifecycle management across compute, storage, and network resources. It provides a centralized portal for administrators and tenants, enabling automated deployment and O & M of cloud services.

FusionSphere is Huawei’s virtualization platform (similar to OpenStack + hypervisor integration) and operates at the resource layer, not as the top-level management system. Hypervisor and Virtual Machine Monitor (VMM) are components of the virtualization layer that manage virtual machines on physical servers, but they lack cloud-wide orchestration capabilities.

From a Huawei CloudFabric perspective, ManageOne integrates with controllers like iMaster NCE-Fabric to automate network provisioning, enabling seamless underlay and overlay configuration. It supports multi-data-center management, self-service portals, and policy-driven automation, which are essential for modern cloud data center operations.

Therefore, ManageOne is the correct answer as the cloud management platform in HCS.

In Huawei CloudFabric’s cloud-network integration scenario , the SDN controller iMaster NCE-Fabric must interconnect with multiple key components to enable end-to-end automation and orchestration .

Cloud platform (A): Platforms such as OpenStack or ManageOne integrate with iMaster NCE-Fabric via northbound APIs. This allows automatic network provisioning when tenants create networks, VMs, or services.

VMM (C - Virtual Machine Manager): Integration with virtualization platforms (e.g., VMware vCenter, FusionSphere) enables dynamic VM-aware networking, including automatic port and policy configuration.

Physical switch (D): These are the core devices controlled by iMaster NCE-Fabric. The controller pushes configurations (VXLAN, EVPN, routing) to build the underlay and overlay fabric.

Firewall (B) is typically integrated as a service device (VAS) but is not directly required to interconnect with the controller in all scenarios. It is usually inserted via service chaining rather than direct control-plane integration.

Huawei emphasizes controller-based automation , where iMaster NCE-Fabric coordinates between cloud platforms, virtualization systems, and physical network devices.

Therefore, the correct answers are A, C, and D .