- A
SD-WAN architecture separates the control plane and data plane, allowing centralized policy management.
Correct because SD-WAN uses a controller-based approach where the control plane is centralized, simplifying policy deployment.
- B
Dual-homing a branch office to two different service provider routers increases WAN availability.
Correct because dual-homing provides redundancy; if one link or provider fails, traffic can use the other.
- C
DMVPN requires a full mesh of static IPsec tunnels between all spoke routers.
Why wrong: Incorrect because DMVPN uses dynamic mGRE tunnels and NHRP to build tunnels on demand, not static full mesh.
- D
MPLS Layer 3 VPNs use Virtual Routing and Forwarding (VRF) instances to provide customer isolation.
Correct because MPLS L3VPNs assign a VRF per customer, keeping routing tables separate and allowing overlapping IP addresses.
- E
DMVPN requires a full mesh of IPsec tunnels between all spoke routers.
Why wrong: Incorrect because DMVPN typically uses a hub-and-spoke topology; spokes do not need to form tunnels with each other unless configured for spoke-to-spoke.
Quick Answer
The correct answer is that MPLS Layer 3 VPNs use Virtual Routing and Forwarding (VRF) instances to provide customer isolation, as this is a foundational enterprise WAN design principle. VRFs create separate routing tables on the same physical infrastructure, allowing overlapping IP addresses between customers while keeping traffic completely segregated, which is essential for multi-tenant MPLS VPN deployments. On the ENCOR 350-401 exam, this concept tests your understanding of how service providers and large enterprises segment traffic without requiring separate hardware, often appearing alongside SD-WAN and dual-homing questions. A common trap is confusing DMVPN’s dynamic mGRE tunnels with MPLS’s VRF-based isolation, or assuming DMVPN requires a full mesh when it actually uses hub-and-spoke. Remember the memory tip: “VRFs isolate, DMVPNs tunnel, and dual-homing keeps you from falling.”
350-401 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.
Which three statements about the Cisco Enterprise WAN design principles are true? (Choose three.)
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
SD-WAN architecture separates the control plane and data plane, allowing centralized policy management.
Enterprise WAN design focuses on connecting remote sites reliably and efficiently. SD-WAN decouples control and data planes for centralized management. Dual-homing provides redundancy. MPLS VPNs offer any-to-any connectivity but with a full mesh of VRFs. Option A is correct because SD-WAN's centralized controller manages policies and path selection. Option B is correct because dual-homing to different provider routers improves availability. Option D is correct because MPLS VPNs use VRFs to isolate customer routing, allowing overlapping addresses. Option C is incorrect because DMVPN uses dynamic tunnels (mGRE/NHRP), not static IPsec tunnels. Option E is incorrect because DMVPN does not require a full mesh; it uses a hub-and-spoke or partial mesh topology.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
SD-WAN architecture separates the control plane and data plane, allowing centralized policy management.
Why this is correct
Correct because SD-WAN uses a controller-based approach where the control plane is centralized, simplifying policy deployment.
Related concept
Static NAT maps one inside address to one outside address.
- ✓
Dual-homing a branch office to two different service provider routers increases WAN availability.
Why this is correct
Correct because dual-homing provides redundancy; if one link or provider fails, traffic can use the other.
Related concept
Static NAT maps one inside address to one outside address.
- ✗
DMVPN requires a full mesh of static IPsec tunnels between all spoke routers.
Why it's wrong here
Incorrect because DMVPN uses dynamic mGRE tunnels and NHRP to build tunnels on demand, not static full mesh.
- ✓
MPLS Layer 3 VPNs use Virtual Routing and Forwarding (VRF) instances to provide customer isolation.
Why this is correct
Correct because MPLS L3VPNs assign a VRF per customer, keeping routing tables separate and allowing overlapping IP addresses.
Related concept
Static NAT maps one inside address to one outside address.
- ✗
DMVPN requires a full mesh of IPsec tunnels between all spoke routers.
Why it's wrong here
Incorrect because DMVPN typically uses a hub-and-spoke topology; spokes do not need to form tunnels with each other unless configured for spoke-to-spoke.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
- Static NAT maps one inside address to one outside address.
- PAT allows many inside hosts to share one public address using ports.
- Inside local and inside global describe the private and translated addresses.
- NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
- Identify inside and outside interfaces first.
- Check whether the scenario needs static NAT, dynamic NAT or PAT.
- Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 350-401 NAT questions on configuration and troubleshooting.
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FAQ
Questions learners often ask
What does this 350-401 question test?
Enterprise Network Design — This question tests Enterprise Network Design — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: SD-WAN architecture separates the control plane and data plane, allowing centralized policy management. — Enterprise WAN design focuses on connecting remote sites reliably and efficiently. SD-WAN decouples control and data planes for centralized management. Dual-homing provides redundancy. MPLS VPNs offer any-to-any connectivity but with a full mesh of VRFs. Option A is correct because SD-WAN's centralized controller manages policies and path selection. Option B is correct because dual-homing to different provider routers improves availability. Option D is correct because MPLS VPNs use VRFs to isolate customer routing, allowing overlapping addresses. Option C is incorrect because DMVPN uses dynamic tunnels (mGRE/NHRP), not static IPsec tunnels. Option E is incorrect because DMVPN does not require a full mesh; it uses a hub-and-spoke or partial mesh topology.
What should I do if I get this 350-401 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 350-401 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Last reviewed: Jun 18, 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.
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