- A
Deploy redundant vSmart controllers in active/standby mode and configure WAN edge routers to use both for OMP sessions.
Why wrong: While redundant vSmart controllers improve control plane availability, if all vSmart controllers become unreachable, OMP sessions are lost and new routes cannot be learned.
- B
Enable OMP graceful restart on all WAN edge routers so that routes are preserved for a configurable period after vSmart loss.
Why wrong: OMP graceful restart helps preserve routes during a brief vSmart restart, but it does not allow the data plane to operate indefinitely without vSmart.
- C
Configure local policies on WAN edge routers to allow forwarding based on the last known OMP routes and locally originated routes.
This approach allows the data plane to continue forwarding using cached routes and local routes even when vSmart is unreachable, maintaining site-to-site connectivity.
- D
Use static routes on the WAN edge routers as a backup for all OMP-learned routes.
Why wrong: Static routes can provide backup connectivity but do not scale to 500 branches and do not leverage the dynamic nature of SD-WAN.
Quick Answer
The correct design approach is to configure local policies on WAN edge routers to allow forwarding based on the last known OMP routes and locally originated routes. This works because Cisco SD-WAN edge routers cache the Overlay Management Protocol (OMP) routes received from vSmart controllers; when vSmart becomes unreachable, the router can continue making forwarding decisions using this cached information combined with any locally generated routes, such as those for directly connected networks or static routes. On the ENCOR 350-401 exam, this scenario tests your understanding of control plane resilience, specifically how the SD-WAN fabric maintains data plane continuity during a vSmart failure. A common trap is assuming that vSmart is required for all forwarding, but the key insight is that OMP routes are distributed to edge routers, which can operate autonomously for a time. Memory tip: think “Cached OMP keeps the traffic flowing” — the edge router holds its own map, so losing the controller doesn’t lose the path.
350-401 SD-WAN Architecture Practice Question
This 350-401 practice question tests your understanding of sd-wan architecture. 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.
A multinational enterprise is deploying Cisco SD-WAN to interconnect 500 branch sites with two data centers. The network architect must ensure that the control plane remains operational even if the vSmart controllers become unreachable. Which design approach should the architect choose to meet this requirement?
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
Configure local policies on WAN edge routers to allow forwarding based on the last known OMP routes and locally originated routes.
Option C is correct because Cisco SD-WAN WAN edge routers can continue forwarding traffic using locally originated routes and the last known OMP routes even when vSmart controllers are unreachable. This is achieved through local policies that allow the router to maintain forwarding decisions based on cached OMP information, ensuring the control plane remains operational without requiring vSmart reachability.
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.
- ✗
Deploy redundant vSmart controllers in active/standby mode and configure WAN edge routers to use both for OMP sessions.
Why it's wrong here
While redundant vSmart controllers improve control plane availability, if all vSmart controllers become unreachable, OMP sessions are lost and new routes cannot be learned.
- ✗
Enable OMP graceful restart on all WAN edge routers so that routes are preserved for a configurable period after vSmart loss.
Why it's wrong here
OMP graceful restart helps preserve routes during a brief vSmart restart, but it does not allow the data plane to operate indefinitely without vSmart.
- ✓
Configure local policies on WAN edge routers to allow forwarding based on the last known OMP routes and locally originated routes.
Why this is correct
This approach allows the data plane to continue forwarding using cached routes and local routes even when vSmart is unreachable, maintaining site-to-site connectivity.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use static routes on the WAN edge routers as a backup for all OMP-learned routes.
Why it's wrong here
Static routes can provide backup connectivity but do not scale to 500 branches and do not leverage the dynamic nature of SD-WAN.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume redundant vSmart controllers or OMP graceful restart are the solutions for control plane resilience, but Cisco SD-WAN does not support OMP graceful restart, and vSmart redundancy alone does not protect against complete loss of reachability to all vSmart controllers.
Detailed technical explanation
How to think about this question
In Cisco SD-WAN, when vSmart controllers are unreachable, WAN edge routers rely on the last known OMP routes stored in the local routing table and any locally originated routes (e.g., connected, static, or redistributed). Local policies can be configured to ensure that these routes remain active and are used for forwarding decisions, preventing traffic disruption. This design leverages the fact that OMP routes are cached locally, and the router does not require continuous vSmart connectivity to maintain forwarding, though new route updates or policy changes will not be received until connectivity is restored.
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 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
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FAQ
Questions learners often ask
What does this 350-401 question test?
SD-WAN Architecture — This question tests SD-WAN Architecture — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Configure local policies on WAN edge routers to allow forwarding based on the last known OMP routes and locally originated routes. — Option C is correct because Cisco SD-WAN WAN edge routers can continue forwarding traffic using locally originated routes and the last known OMP routes even when vSmart controllers are unreachable. This is achieved through local policies that allow the router to maintain forwarding decisions based on cached OMP information, ensuring the control plane remains operational without requiring vSmart reachability.
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.
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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.
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