- A
Spine switches must run Spanning Tree Protocol (STP) to prevent loops
Why wrong: Leaf-spine uses Layer 3 routing with ECMP; STP is not needed and would block redundant paths.
- B
Spine switches must support high port density and high forwarding capacity, and act as Layer 3 routers
Spine switches are the backbone, forwarding traffic between leaf switches using Layer 3 routing and ECMP for load balancing.
- C
Spine switches must be connected to each other to provide redundancy
Why wrong: Spine switches are not connected to each other; redundancy is achieved by having multiple spines, and leaf switches connect to all spines.
- D
Spine switches must perform NAT to translate between VLANs
Why wrong: NAT is not used in leaf-spine; traffic is routed between subnets using standard IP routing.
CCNP Enterprise Network Design Practice Question
This 350-401 practice question tests your understanding of enterprise network design. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
An enterprise is migrating its data center to a leaf-spine architecture to support high east-west traffic between servers. The design must provide non-blocking forwarding and allow for easy scaling by adding more spines. Which characteristic is essential for the spine switches in this design?
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
Spine switches must support high port density and high forwarding capacity, and act as Layer 3 routers
In a leaf-spine architecture designed for non-blocking forwarding and high east-west traffic, spine switches must act as Layer 3 routers with high port density and forwarding capacity. This allows them to perform Equal-Cost Multi-Path (ECMP) routing, which distributes traffic across all available uplinks without blocking, ensuring that any leaf can reach any other leaf with predictable latency and full bandwidth utilization.
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.
- ✗
Spine switches must run Spanning Tree Protocol (STP) to prevent loops
Why it's wrong here
Leaf-spine uses Layer 3 routing with ECMP; STP is not needed and would block redundant paths.
- ✓
Spine switches must support high port density and high forwarding capacity, and act as Layer 3 routers
Why this is correct
Spine switches are the backbone, forwarding traffic between leaf switches using Layer 3 routing and ECMP for load balancing.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Spine switches must be connected to each other to provide redundancy
Why it's wrong here
Spine switches are not connected to each other; redundancy is achieved by having multiple spines, and leaf switches connect to all spines.
- ✗
Spine switches must perform NAT to translate between VLANs
Why it's wrong here
NAT is not used in leaf-spine; traffic is routed between subnets using standard IP routing.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that STP is needed in all redundant switch designs, but in a Layer 3 leaf-spine architecture, STP is not used because routing protocols inherently prevent loops and allow all links to be active.
Detailed technical explanation
How to think about this question
Under the hood, spine switches in a leaf-spine fabric typically run a routing protocol like BGP (often with an overlay such as VXLAN/EVPN) to exchange loop-free paths and enable ECMP. For non-blocking forwarding, the spine-to-leaf oversubscription ratio must be 1:1, meaning the aggregate bandwidth from each leaf to the spines equals the leaf's server-facing bandwidth. In real-world deployments, scaling is achieved by adding more spines, which increases the number of ECMP paths and total fabric capacity without requiring any changes to the leaf switches.
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.
- →
Enterprise Network Design — study guide chapter
Learn the concepts, then practise the questions
- →
Enterprise Network Design practice questions
Targeted practice on this topic area only
- →
All 350-401 questions
2,015 questions across all exam domains
- →
ENCOR 350-401 study guide
Full concept coverage aligned to exam objectives
- →
350-401 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
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.
FAQ
Questions learners often ask
What does this 350-401 question test?
Enterprise Network Design — This question tests Enterprise Network Design — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Spine switches must support high port density and high forwarding capacity, and act as Layer 3 routers — In a leaf-spine architecture designed for non-blocking forwarding and high east-west traffic, spine switches must act as Layer 3 routers with high port density and forwarding capacity. This allows them to perform Equal-Cost Multi-Path (ECMP) routing, which distributes traffic across all available uplinks without blocking, ensuring that any leaf can reach any other leaf with predictable latency and full bandwidth utilization.
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.
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 →
Keep practising
More 350-401 practice questions
- Drag and drop the steps to configure an extended access control list (ACL) on a Cisco router in the correct order.
- Drag and drop the steps to configure a site-to-site IPsec VPN on a Cisco router in the correct order.
- Drag and drop the steps to configure VLAN Trunking Protocol (VTP) on a Cisco switch in the correct order.
- Drag and drop the steps to configure a static route on a Cisco IOS router into the correct order.
- Drag and drop the steps to configure port security on a Cisco switch in the correct order.
- Drag and drop the steps for the Spanning Tree Protocol (STP) convergence process in the correct order.
Last reviewed: Jun 24, 2026
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.
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.