easyMultiple ChoiceObjective-mapped
350-401 Practice Question: Is configuring model-driven telemetry on a Cisco…
A network engineer is configuring model-driven telemetry on a Cisco IOS-XE router to stream OSPF neighbor state changes. The engineer uses the YANG model 'Cisco-IOS-XE-ospf-oper' and creates an on-change subscription. After testing, the engineer notices that the telemetry data is being sent, but the collector is receiving duplicate updates for the same OSPF neighbor state change. What is the most likely cause of these duplicate updates?
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 YANG path includes multiple leafs that change together, each triggering a separate update
That the YANG path includes multiple leafs that change simultaneously, causing multiple updates for the same event. For example, when an OSPF neighbor goes from FULL to DOWN, multiple leafs (state, last-up-time, etc.) change, and each change triggers an on-change update. The other options are incorrect because the sample-interval is not used in on-change subscriptions; the collector is not causing duplicates; and the encoding does not cause duplicates.
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 subscription is configured with both on-change and periodic updates
Why it's wrong here
On-change subscriptions do not support periodic updates; if both are configured, it would be an error.
- ✓
The YANG path includes multiple leafs that change together, each triggering a separate update
Why this is correct
On-change subscriptions send an update for each leaf that changes, so multiple leaf changes from a single event cause duplicate updates.
- ✗
The collector is sending acknowledgments that cause the router to resend data
Why it's wrong here
gRPC does not use acknowledgments for telemetry data; it is a one-way stream.
- ✗
The engineer used JSON encoding which causes larger payloads and fragmentation
Why it's wrong here
Encoding does not cause duplicate updates; fragmentation would not create duplicates.
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.