Question 153 of 2,015

SD-Access Architecture →hardMultiple ChoiceObjective-mapped

Quick Answer

The answer is that the endpoints are in the same IP subnet, so they must be in the same Virtual Network; SGT enforcement only applies to inter-VN traffic. This is because in Cisco SD-Access, Virtual Networks (VNs) provide Layer 3 segmentation, meaning traffic within the same subnet is inherently Layer 2 and is switched locally at the fabric edge without any routing or SGT inspection. SGT enforcement is a Layer 3 policy mechanism that only triggers when traffic crosses VNs, so when two hosts share a subnet, the fabric edge assumes they belong to the same VN and forwards the frames directly. On the ENCOR 350-401 exam, this question tests your understanding of the boundary between Layer 2 switching and Layer 3 policy enforcement in SD-Access, often trapping candidates who assume SGTs apply to all traffic. A common memory tip is: “Same subnet, same VN — no SGT inspection; different subnet, different VN — SGT kicks in.”

350-401 SD-Access Architecture Practice Question

This 350-401 practice question tests your understanding of sd-access architecture. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 network engineer is deploying Cisco SD-Access in a large enterprise campus. The design requires that all user traffic be segmented by Virtual Network (VN) and that the fabric edge nodes perform SGT-based enforcement. The engineer notices that traffic between two endpoints in the same IP subnet but different VNs is being forwarded directly at the fabric edge without any SGT inspection. What is the most likely cause?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

Question 1hardmultiple choice

Study the full SD-Access breakdown →

A
The fabric edge nodes have not been configured with the proper SGT mappings.
Why wrong: Incorrect because SGT mappings are used for SXP propagation, not for enforcement at the fabric edge. The issue is not about missing mappings.
B
The endpoints are in the same IP subnet, so they must be in the same Virtual Network; SGT enforcement only applies to inter-VN traffic.
Correct. In SD-Access, endpoints in the same subnet belong to the same VN. SGT enforcement is only performed when traffic crosses VNs (inter-VN). Intra-VN traffic is bridged locally without SGT inspection.
C
The fabric edge nodes are operating in Layer 2 mode and do not support SGT enforcement.
Why wrong: Incorrect. Fabric edge nodes can perform SGT enforcement regardless of Layer 2 or Layer 3 mode. The mode affects how traffic is forwarded but not SGT enforcement capability.
D
The control plane node has not been configured with the correct IP-SGT mappings.
Why wrong: Incorrect. IP-SGT mappings are used for SXP and policy enforcement, but the scenario describes traffic within the same subnet, which is intra-VN and does not trigger SGT enforcement.

Full breakdown with real-world context →

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

✓

The endpoints are in the same IP subnet, so they must be in the same Virtual Network; SGT enforcement only applies to inter-VN traffic.

In Cisco SD-Access, Virtual Networks (VNs) provide Layer 3 segmentation. Traffic between endpoints in the same IP subnet but different VNs is inherently Layer 2 traffic and cannot be routed or inspected by SGT-based enforcement, which only applies to inter-VN (Layer 3) traffic. Since the endpoints are in the same subnet, the fabric edge node forwards the traffic at Layer 2 without SGT inspection, making option B correct.

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.

✗
The fabric edge nodes have not been configured with the proper SGT mappings.
Why it's wrong here
Incorrect because SGT mappings are used for SXP propagation, not for enforcement at the fabric edge. The issue is not about missing mappings.
✓
The endpoints are in the same IP subnet, so they must be in the same Virtual Network; SGT enforcement only applies to inter-VN traffic.
Why this is correct
Correct. In SD-Access, endpoints in the same subnet belong to the same VN. SGT enforcement is only performed when traffic crosses VNs (inter-VN). Intra-VN traffic is bridged locally without SGT inspection.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The fabric edge nodes are operating in Layer 2 mode and do not support SGT enforcement.
Why it's wrong here
Incorrect. Fabric edge nodes can perform SGT enforcement regardless of Layer 2 or Layer 3 mode. The mode affects how traffic is forwarded but not SGT enforcement capability.
✗
The control plane node has not been configured with the correct IP-SGT mappings.
Why it's wrong here
Incorrect. IP-SGT mappings are used for SXP and policy enforcement, but the scenario describes traffic within the same subnet, which is intra-VN and does not trigger SGT enforcement.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates assume SGT enforcement applies to all traffic between different VNs, forgetting that same-subnet traffic is Layer 2 and thus not subject to Layer 3 SGT inspection, leading them to incorrectly focus on configuration issues like missing SGT mappings.

Trap categories for this question

Scenario analysis trap
Incorrect. IP-SGT mappings are used for SXP and policy enforcement, but the scenario describes traffic within the same subnet, which is intra-VN and does not trigger SGT enforcement.

Detailed technical explanation

How to think about this question

In SD-Access, SGT-based enforcement (using Cisco TrustSec) operates at Layer 3, where the fabric edge node applies SGTs to packets traversing the overlay (VXLAN). When two endpoints are in the same IP subnet but different VNs, the traffic is bridged locally at the fabric edge without being encapsulated into the VXLAN tunnel, so no SGT inspection occurs. This behavior is by design, as VNs are Layer 3 domains, and intra-subnet traffic is handled at Layer 2, bypassing the SGT enforcement logic.

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 network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.

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.

Related 350-401 practice-question pages

Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.

Architecture practice questions

Practise 350-401 questions linked to Architecture.

Enterprise Network Design practice questions

Practise 350-401 questions linked to Enterprise Network Design.

SD-Access Architecture practice questions

Practise 350-401 questions linked to SD-Access Architecture.

SD-WAN Architecture practice questions

Practise 350-401 questions linked to SD-WAN Architecture.

QoS Architecture practice questions

Practise 350-401 questions linked to QoS Architecture.

Virtualization practice questions

Practise 350-401 questions linked to Virtualization.

Network Function Virtualization practice questions

Practise 350-401 questions linked to Network Function Virtualization.

Virtual Machines and Hypervisors practice questions

Practise 350-401 questions linked to Virtual Machines and Hypervisors.

VRF and Path Isolation practice questions

Practise 350-401 questions linked to VRF and Path Isolation.

Infrastructure practice questions

Practise 350-401 questions linked to Infrastructure.

OSPF practice questions

Practise 350-401 questions linked to OSPF.

BGP practice questions

Practise 350-401 questions linked to BGP.

Practice this exam

Start a free 350-401 practice session

Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.

10 questions 20 questions 30 questions 50 questions Timed 30

350-401 practice-test guide →Study guide →Browse all practice tests

FAQ

Questions learners often ask

What does this 350-401 question test?

SD-Access Architecture — This question tests SD-Access Architecture — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: The endpoints are in the same IP subnet, so they must be in the same Virtual Network; SGT enforcement only applies to inter-VN traffic. — In Cisco SD-Access, Virtual Networks (VNs) provide Layer 3 segmentation. Traffic between endpoints in the same IP subnet but different VNs is inherently Layer 2 traffic and cannot be routed or inspected by SGT-based enforcement, which only applies to inter-VN (Layer 3) traffic. Since the endpoints are in the same subnet, the fabric edge node forwards the traffic at Layer 2 without SGT inspection, making option B correct.

What should I do if I get this 350-401 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: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

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 →

How Courseiva writes practice questions · Editorial policy

Keep practising

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.

Loading comments…

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.