The answer is to implement a Layer 2 gateway (L2GW) on the leaf switches using an Integrated Routing and Bridging (IRB) interface. This is correct because the IRB interface acts as the bridge between the legacy VLAN and the VXLAN segment, performing the VLAN-to-VXLAN mapping and handling ARP suppression, which allows the legacy server to communicate across the new fabric without any configuration changes. On the Cisco DevNet Associate 200-901 exam, this scenario tests your understanding of VXLAN legacy VLAN integration and how to eliminate STP in a leaf-spine design; a common trap is confusing a Layer 2 gateway with a Layer 3 gateway, but remember that the L2GW bridges at Layer 2, not routes. Memory tip: "IRB bridges the gap" — think of IRB as the translator that lets old VLANs talk to new VXLANs without the server knowing.
200-901 Network Fundamentals Practice Question
This 200-901 practice question tests your understanding of network fundamentals. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company has a three-tier data center architecture with access, aggregation, and core layers. The network team is migrating to a leaf-spine architecture to support increasing east-west traffic. The current network uses STP for loop prevention, and the team wants to eliminate STP in the new design. They plan to use VXLAN overlays with BGP EVPN for control plane. During a pilot deployment, the team notices that some legacy servers that rely on traditional VLANs are not reachable across the new fabric. The servers are connected to access switches that are part of the leaf layer. The access switches are configured as VXLAN tunnel endpoints (VTEPs) but the legacy servers are still using traditional VLANs. The team needs to ensure connectivity between the legacy VLAN-based servers and the new VXLAN-based network. What is the best approach to integrate these legacy servers without changing their configuration?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Implement a Layer 2 gateway (L2GW) on the leaf switches to bridge VLANs to VXLAN using IRB
Option B is correct because an Integrated Routing and Bridging (IRB) interface on the leaf switch acts as a Layer 2 gateway (L2GW), bridging the legacy VLAN to a VXLAN segment. This allows the legacy server, which still uses traditional VLAN tagging, to communicate with the VXLAN-based fabric without any configuration changes on the server. The IRB interface performs the VLAN-to-VXLAN mapping and handles ARP suppression, enabling seamless integration.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Create a separate VRF for legacy VLANs and redistribute into BGP EVPN
Why it's wrong here
This adds complexity and does not solve L2 connectivity.
✓
Implement a Layer 2 gateway (L2GW) on the leaf switches to bridge VLANs to VXLAN using IRB
Why this is correct
IRB provides seamless bridging between VLAN and VXLAN.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Configure the same VLAN on all leaf switches and use VXLAN to stretch the VLAN across the fabric
Why it's wrong here
Stretching VLANs is not recommended for large fabrics.
✗
Reconfigure the legacy servers to use VXLAN encapsulation
Why it's wrong here
Server configuration change is to be avoided.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Layer 2 stretching (Option C) with a Layer 2 gateway, not realizing that stretching VLANs across the fabric would reintroduce STP dependencies and does not provide the necessary gateway function for legacy VLAN-based devices.
Detailed technical explanation
How to think about this question
In a VXLAN fabric with BGP EVPN, the IRB interface (often configured as an SVI with 'xconnect' or 'bridge-domain' mapping) performs VLAN-to-VXLAN translation at the leaf. The IRB also handles ARP suppression by caching ARP entries learned from the legacy VLAN, reducing broadcast traffic. In real-world scenarios, this approach is critical for brownfield deployments where legacy servers must be integrated without downtime or reconfiguration.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Network Fundamentals — This question tests Network Fundamentals — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Implement a Layer 2 gateway (L2GW) on the leaf switches to bridge VLANs to VXLAN using IRB — Option B is correct because an Integrated Routing and Bridging (IRB) interface on the leaf switch acts as a Layer 2 gateway (L2GW), bridging the legacy VLAN to a VXLAN segment. This allows the legacy server, which still uses traditional VLAN tagging, to communicate with the VXLAN-based fabric without any configuration changes on the server. The IRB interface performs the VLAN-to-VXLAN mapping and handles ARP suppression, enabling seamless integration.
What should I do if I get this 200-901 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This 200-901 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 200-901 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.