350-401 Infrastructure Practice Question
A network engineer is deploying a VXLAN EVPN fabric. The underlay is a routed Layer 3 network using OSPF. Hosts in the same subnet are attached to leaf switches that are not directly connected. The engineer must ensure that the fabric provides optimal forwarding for East-West traffic without tromboning through a centralized gateway. Which VXLAN component should be configured to accomplish this?
⚠ Common exam trap
The trap here is assuming that any gateway configuration will automatically optimize East-West traffic, when in fact only a distributed anycast gateway avoids tromboning.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Anycast distributed gateway with the same MAC and IP on all leaf switches
An anycast distributed gateway places the same gateway IP and MAC on every leaf switch, allowing each leaf to route traffic for its local hosts. This eliminates the need to send traffic to a centralized gateway, providing optimal East-West forwarding. It is a key feature of VXLAN EVPN fabrics for efficient inter-subnet routing.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Anycast distributed gateway with the same MAC and IP on all leaf switches
Why this is correct
An anycast distributed gateway configures the same gateway IP and MAC on every leaf switch, so each leaf can route traffic locally for its directly attached hosts. This avoids sending traffic to a centralized gateway and prevents suboptimal tromboning. It is the standard VXLAN EVPN design for optimal East-West forwarding.
- ✗
OSPF area 0 with stub areas on all leaf switches to reduce LSAs
Why it's wrong here
OSPF stub areas reduce link-state advertisements but do not enable distributed anycast gateway. The underlay routing protocol choice does not provide the overlay gateway redundancy and local routing needed for optimal East-West traffic. Stub areas would not solve the tromboning issue.
- ✗
Static VXLAN tunnel endpoints mapped to each leaf switch's loopback address
Why it's wrong here
Static VXLAN tunnels require manual mapping of remote VTEPs and do not dynamically adapt to topology changes. They also do not provide distributed anycast gateway functionality, so traffic would still need a centralized gateway for inter-subnet routing. This approach is not suitable for a scalable EVPN fabric.
- ✗
VXLAN Network Identifier (VNI) mapping to a single centralized gateway
Why it's wrong here
Mapping a VNI to a centralized gateway forces all inter-subnet traffic to traverse that gateway, which causes tromboning and suboptimal paths. This design does not distribute routing to the leaf switches, so East-West traffic between hosts on different leaves would hairpin through the central gateway.
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
Go deeper
Related to this question
Learn chapter
Spine-Leaf and Software-Defined Network Architectures
Key term
VXLAN
VXLAN is a network overlay technology that encapsulates Layer 2 Ethernet frames in UDP packets to extend VLANs across Layer 3 networks.
Key term
Fabric Fundamentals
Fabric Fundamentals is the set of core concepts behind a network fabric, where switches and routers form a single logical system that simplifies traffic forwarding and automation.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 350-401 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-401 exam.