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Question 181. What is the PRIMARY purpose of VXLAN in a modern data center network?

1. To replace IP routing with STP
2. To build scalable virtual Layer 2 or Layer 3 networks over an IP underlay
3. To provide only physical port aggregation
4. To replace all BGP routing with static routes

Correct Answer: 2. To build scalable virtual Layer 2 or Layer 3 networks over an IP underlay

Explanation:

VXLAN, or Virtual Extensible LAN, is a network virtualization technology that builds logical overlay networks across an existing IP underlay. It allows Layer 2 segments to be extended across routed infrastructure without requiring the physical network itself to operate as one large Layer 2 domain. This is especially useful in data centers containing many tenants, virtual machines, and dynamically changing workloads. VXLAN separates the logical tenant network from the physical topology, improving scalability and flexibility. Huawei describes VXLAN as an NVO3 technology that encapsulates tenant traffic so it can traverse ordinary Layer 3 networks.

Question 182. Which encapsulation method is used by VXLAN to transport original Ethernet frames across an IP network?

1. Ethernet-in-MPLS only
2. GRE without UDP
3. PPP-in-IP
4. MAC-in-UDP encapsulation

Correct Answer: 4. MAC-in-UDP encapsulation

Explanation:

VXLAN uses MAC-in-UDP encapsulation. The original Ethernet frame generated by a tenant host or virtual machine is encapsulated inside a VXLAN header and UDP packet. Outer IP and Ethernet headers are then added so the resulting packet can be routed normally across the physical IP network. The destination VXLAN tunnel endpoint removes the outer encapsulation and reconstructs the original Ethernet frame before delivering it locally. This mechanism enables Layer 2 virtual networks to span Layer 3 infrastructure without requiring intermediate underlay routers to learn every tenant MAC address.

Question 183. What is the role of a VTEP in a VXLAN network?

1. It encapsulates and decapsulates tenant Ethernet frames at the endpoints of VXLAN tunnels
2. It functions only as an STP root bridge
3. It assigns DHCP addresses to every tenant
4. It replaces the physical IP underlay

Correct Answer: 1. It encapsulates and decapsulates tenant Ethernet frames at the endpoints of VXLAN tunnels

Explanation:

A VXLAN Tunnel Endpoint (VTEP) is positioned at the edge of a VXLAN network. The source VTEP takes an original Ethernet frame from a tenant network, adds VXLAN, UDP, IP, and outer Ethernet headers, and sends the encapsulated packet across the underlay. The destination VTEP removes this encapsulation and delivers the original frame toward the destination endpoint. Because encapsulation and decapsulation occur at VTEPs, intermediate IP routers do not need to understand tenant MAC addressing. VTEPs therefore connect the virtual overlay topology to the physical routed network underneath it.

Question 184. What does a VXLAN Network Identifier (VNI) primarily identify?

1. An OSPF area
2. A BGP autonomous system
3. A VXLAN segment or tenant virtual network
4. A physical Ethernet interface

Correct Answer: 3. A VXLAN segment or tenant virtual network

Explanation:

The VNI identifies a VXLAN virtual network in much the same conceptual way that a VLAN ID identifies a VLAN. The VXLAN header contains a 24-bit VNI field, allowing approximately 16 million possible VXLAN segments. This is substantially more than the roughly 4096 VLAN identifiers supported by traditional IEEE 802.1Q VLANs. Different VNIs provide logical separation between tenant networks, so hosts in different Layer 2 VNIs do not communicate directly at Layer 2 unless routing or another gateway function is provided between them.

Question 185. In VXLAN terminology, what is the underlay network?

1. The tenant’s virtual Layer 2 network only
2. The VM operating-system network stack
3. The EVPN MAC address table
4. The physical IP network that provides reachability between VTEPs

Correct Answer: 4. The physical IP network that provides reachability between VTEPs

Explanation:

The underlay is the physical network infrastructure over which VXLAN packets travel. It is typically an IP-routed network providing reliable reachability between VTEP addresses. Routing protocols such as OSPF, IS-IS, or BGP may be used to build underlay connectivity depending on the design. VXLAN tenant networks are then constructed as overlays above this physical infrastructure. The underlay does not need detailed knowledge of tenant MAC addresses or individual virtual networks; it primarily needs to ensure that the VTEPs can reach one another using Layer 3 forwarding.

Question 186. What is the VXLAN overlay network?

1. The physical cabling between switches
2. The logical tenant network built across the physical underlay using VXLAN encapsulation
3. A replacement for every IP routing protocol
4. Only the management network of the switches

Correct Answer: 2. The logical tenant network built across the physical underlay using VXLAN encapsulation

Explanation:

The overlay network is the logical Layer 2 or Layer 3 tenant network created on top of the physical underlay. Tenant packets are encapsulated at VTEPs, transported across the IP underlay, and decapsulated at the remote VTEP. Because the overlay is logically independent of the physical network layout, tenants can have their own addressing and broadcast domains without being tightly coupled to the physical topology. This separation is a major reason VXLAN is useful in cloud and large data center environments, where workloads may move dynamically while their logical networks must remain consistent.

Question 187. What is the PRIMARY function of a Layer 2 VNI?

1. To identify a VXLAN segment used for intra-subnet Layer 2 forwarding
2. To carry only Internet routes
3. To identify an OSPF virtual link
4. To represent a physical spine switch

Correct Answer: 1. To identify a VXLAN segment used for intra-subnet Layer 2 forwarding

Explanation:

A Layer 2 VNI identifies a VXLAN segment used primarily for forwarding traffic within the same logical subnet or broadcast domain. Hosts associated with the same Layer 2 VNI can communicate across VXLAN tunnels as though they belonged to the same extended Layer 2 network, even if they are attached to different physical switches. Huawei distinguishes Layer 2 VNIs from Layer 3 VNIs. A Layer 3 VNI is associated with a VPN instance and supports inter-subnet routing, whereas a Layer 2 VNI represents ordinary intra-subnet VXLAN forwarding.

Question 188. What is the PRIMARY role of a Layer 3 VNI in VXLAN?

1. To identify only a physical trunk port
2. To perform STP calculations
3. To support inter-subnet forwarding by associating VXLAN with a Layer 3 VPN or routing instance
4. To replace the VTEP address

Correct Answer: 3. To support inter-subnet forwarding by associating VXLAN with a Layer 3 VPN or routing instance

Explanation:

A Layer 3 VNI is used when VXLAN traffic must be routed between different subnets or tenant Layer 2 segments. Huawei describes a Layer 3 VNI as being associated with a VPN instance for inter-subnet VXLAN forwarding. This allows a VXLAN gateway to maintain tenant-specific routing information and forward traffic between different Layer 2 VNIs while preserving tenant isolation. Layer 2 VNIs handle same-subnet communication, whereas Layer 3 VNIs participate in the routing context required when traffic crosses subnet boundaries.

Question 189. What is the PRIMARY benefit of using EVPN as the control plane for VXLAN?

1. It enables control-plane distribution of VTEP and host information, reducing dependence on flooding
2. It eliminates the need for an underlay IP network
3. It converts VXLAN into STP
4. It limits VXLAN to 4096 tenants

Correct Answer: 1. It enables control-plane distribution of VTEP and host information, reducing dependence on flooding

Explanation:

Original VXLAN designs did not define a dedicated control plane, so VTEP discovery and host learning relied heavily on manual configuration and data-plane flooding. EVPN improves this design by using BGP extensions to distribute Layer 2 and Layer 3 reachability information. VTEPs can dynamically discover one another and advertise MAC, IP, VNI, and prefix information through BGP EVPN routes. This reduces flooding, simplifies expansion, and separates the control plane from the forwarding plane. Huawei specifically describes EVPN as the preferred control-plane mechanism for scalable dynamic VXLAN environments.

Question 190. Which BGP EVPN route type is primarily used to advertise host MAC and IP information?

1. Type 1 only
2. Type 3
3. Type 5
4. Type 2 MAC/IP route

Correct Answer: 4. Type 2 MAC/IP route

Explanation:

A BGP EVPN Type 2 route, also known as a MAC/IP route, carries host reachability information between VTEPs. It can advertise a host’s MAC address and associated IP information, allowing remote VTEPs to learn endpoints through the EVPN control plane instead of depending entirely on data-plane flooding and traditional MAC learning. Type 2 routes are therefore fundamental to scalable VXLAN EVPN host learning. Huawei distinguishes them from Type 3 routes, which help establish BUM forwarding information, and Type 5 routes, which advertise IP prefixes.

Question 191. What is the PRIMARY purpose of an EVPN Type 3 route in a VXLAN network?

1. To advertise only Internet prefixes
2. To carry DHCP lease information
3. To advertise VNI and VTEP information used to establish BUM forwarding or ingress-replication relationships
4. To identify STP root bridges

Correct Answer: 3. To advertise VNI and VTEP information used to establish BUM forwarding or ingress-replication relationships

Explanation:

An EVPN Type 3 route carries information used for VXLAN tunnel and BUM forwarding establishment. Huawei explains that VTEPs exchange Type 3 routes containing Layer 2 VNI and VTEP IP information. This information can be used to establish an ingress replication list so Broadcast, Unknown Unicast, and Multicast traffic can be copied toward the appropriate remote VTEPs. Type 3 routes therefore support automatic discovery and dynamic VXLAN tunnel operation. They should not be confused with Type 2 host routes or Type 5 IP-prefix routes.

Question 192. Which BGP EVPN route type is primarily used to advertise IP prefix routes?

1. Type 2 only
2. Type 5
3. Type 3 only
4. Type 1 only

Correct Answer: 2. Type 5

Explanation:

EVPN Type 5 routes are IP Prefix routes. They allow IP network prefixes to be distributed using the EVPN control plane and are particularly useful for Layer 3 VXLAN and inter-subnet routing scenarios. Huawei distinguishes Type 5 routes from Type 2 routes, which primarily advertise host MAC/IP information, and Type 3 routes, which advertise information used for VTEP discovery and BUM forwarding. Type 5 routes therefore extend EVPN beyond Layer 2 reachability and allow it to support scalable Layer 3 routing information across VXLAN fabrics.

Question 193. What is a major scalability limitation of static VXLAN tunnel configuration?

1. Static VXLAN cannot transport Ethernet frames
2. Static VXLAN cannot use IP networks
3. Static VXLAN supports only one host
4. VTEP and tunnel information must be configured manually, making large deployments difficult to operate and expand

Correct Answer: 4. VTEP and tunnel information must be configured manually, making large deployments difficult to operate and expand

Explanation:

Static VXLAN can work in small environments, but it becomes operationally difficult as the number of VTEPs and tenant segments increases. Tunnel endpoints and related forwarding information may require substantial manual configuration, and host discovery may rely more heavily on flooding. Huawei notes that static VXLAN has poor flexibility and is not well suited to large-scale environments. Dynamic VXLAN using BGP EVPN solves many of these limitations by enabling automatic VTEP discovery, control-plane host advertisement, and dynamic tunnel establishment.

Question 194. What relationship must VTEPs normally establish when EVPN is used to dynamically create VXLAN tunnels?

1. BGP EVPN peer relationships
2. STP neighbor relationships
3. DHCP relay relationships
4. VRRP groups only

Correct Answer: 1. BGP EVPN peer relationships

Explanation:

When EVPN is used as the VXLAN control plane, VTEPs establish BGP EVPN peer relationships and exchange EVPN Network Layer Reachability Information. Through these routes, VTEPs can learn information about remote tunnel endpoints, VNIs, MAC addresses, host IP addresses, and IP prefixes. Huawei notes that Type 3 EVPN routes can be exchanged between VTEPs to advertise VNI and VTEP IP information and dynamically establish VXLAN tunnels. This removes much of the manual configuration required by static VXLAN designs and improves scalability.

Question 195. What does BUM stand for in a VXLAN environment?

1. Bridging, Unicast, and MPLS
2. Broadcast, Unknown Unicast, and Multicast
3. BGP, UDP, and MAC
4. Border, Underlay, and Management

Correct Answer: 2. Broadcast, Unknown Unicast, and Multicast

Explanation:

BUM stands for Broadcast, Unknown Unicast, and Multicast traffic. These traffic types may need to reach multiple VTEPs because the ingress device cannot simply forward them toward one known destination endpoint. In VXLAN, ingress replication is one method of handling BUM traffic. The ingress VTEP creates copies of the VXLAN packet and sends them to the relevant remote VTEPs included in its replication list. EVPN Type 3 routes can help establish the information required to build these replication relationships dynamically.

Question 196. Why does VXLAN scale to significantly more isolated tenant segments than traditional VLAN technology?

1. VXLAN removes all identifiers from frames
2. VXLAN uses only one VLAN for every tenant
3. VXLAN uses a 24-bit VNI, providing roughly 16 million possible segments compared with about 4096 VLAN IDs
4. VXLAN requires one physical switch per tenant

Correct Answer: 3. VXLAN uses a 24-bit VNI, providing roughly 16 million possible segments compared with about 4096 VLAN IDs

Explanation:

Traditional IEEE 802.1Q VLAN tagging uses a 12-bit VLAN identifier space, resulting in approximately 4096 possible VLAN values, with some reserved. Large multi-tenant cloud environments can exceed that scale. VXLAN uses a 24-bit VNI, allowing roughly 16 million logical VXLAN segments. This much larger identifier space allows service providers and data centers to isolate many more tenant networks without being constrained by the traditional VLAN-ID limit. Huawei identifies this expanded tenant scale as one of the major reasons VXLAN was introduced for cloud and large data center environments.

Question 197. Two servers belong to the same Layer 2 VNI but are attached to different VTEPs. What is required for their VXLAN communication?

1. Both servers must use the same physical switch port
2. The VTEPs must have underlay IP reachability and a VXLAN tunnel or equivalent dynamically established forwarding relationship
3. Both VTEPs must be the STP root bridge
4. The servers must use different VNIs

Correct Answer: 2. The VTEPs must have underlay IP reachability and a VXLAN tunnel or equivalent dynamically established forwarding relationship

Explanation:

Hosts in the same Layer 2 VNI can communicate across different physical locations because VXLAN extends the logical Layer 2 segment across an IP network. For this to work, the VTEPs must be reachable through the underlay and need VXLAN forwarding information that identifies the remote endpoint. The tunnel can be configured statically or established dynamically through EVPN. The source VTEP encapsulates the Ethernet frame, sends it across the routed underlay, and the destination VTEP decapsulates it for delivery to the remote server.

Question 198. Two VXLAN hosts reside in different IP subnets. What function is required for them to communicate?

1. Only Layer 2 flooding
2. STP root election
3. DHCP snooping only
4. Layer 3 VXLAN gateway functionality to route between the subnets

Correct Answer: 4. Layer 3 VXLAN gateway functionality to route between the subnets

Explanation:

Hosts in different IP subnets cannot communicate using Layer 2 switching alone. A Layer 3 VXLAN gateway performs routing between the tenant subnets. Huawei distinguishes intra-subnet forwarding, which uses Layer 2 VNIs, from inter-subnet forwarding, which involves Layer 3 routing and typically a Layer 3 VNI associated with a VPN instance. The gateway maintains the required tenant routing information and forwards traffic from one logical VXLAN segment to another while preserving isolation from unrelated tenants.

Question 199. In a typical spine-leaf data center fabric, which statement BEST describes the physical underlay?

1. It must be one large bridged Layer 2 domain
2. It cannot run any routing protocol
3. It commonly provides routed IP connectivity between leaf/VTEP devices through spine switches
4. Every spine must learn every tenant MAC address

Correct Answer: 3. It commonly provides routed IP connectivity between leaf/VTEP devices through spine switches

Explanation:

A modern spine-leaf fabric commonly uses a routed IP underlay. Leaf switches connect workloads and may function as VTEPs, while spine switches provide highly scalable Layer 3 connectivity between leaves. VXLAN overlays then carry tenant Layer 2 or Layer 3 networks above that infrastructure. Because tenant Ethernet frames are encapsulated before crossing the underlay, spine devices generally do not need to maintain every tenant’s MAC table. Huawei CloudFabric documentation describes the physical fabric as interconnected spine and leaf nodes over which logical VXLAN EVPN services can be created.

Question 200. A large data center needs millions of possible tenant segments, Layer 2 extension across routed infrastructure, automatic tunnel discovery, reduced flooding, host MAC/IP advertisement, and scalable inter-subnet routing. Which design BEST satisfies these requirements?

1. Use a routed IP underlay with VXLAN VTEPs and BGP EVPN as the overlay control plane, using appropriate Layer 2 and Layer 3 VNIs
2. Build one large STP domain using traditional VLANs only
3. Use static routes and one shared VLAN for every tenant
4. Disable BGP and configure every remote MAC address manually

Correct Answer: 1. Use a routed IP underlay with VXLAN VTEPs and BGP EVPN as the overlay control plane, using appropriate Layer 2 and Layer 3 VNIs

Explanation:

VXLAN EVPN is well suited to large multi-tenant data centers. A routed underlay provides scalable IP reachability between VTEPs. VXLAN supplies a 24-bit VNI space supporting millions of logical segments, while Layer 2 and Layer 3 VNIs support intra-subnet and inter-subnet forwarding. BGP EVPN adds a scalable control plane for automatic VTEP discovery, host MAC/IP advertisement, prefix distribution, and dynamic tunnel establishment. EVPN also reduces reliance on data-plane flooding. Together, these technologies separate the physical topology from tenant networking and provide a more scalable alternative to building one enormous VLAN and STP domain.