The correct answer is that the configuration on pe1 differs from the service model defined in NSO. This is because the NSO check-sync out-of-sync meaning is rooted in how NSO compares the actual running configuration retrieved from a device—via NETCONF or CLI—against the configuration its service model expects. When the result shows out-of-sync, it indicates configuration drift has occurred, meaning the device’s real state no longer matches NSO’s intended state for that service. On the Cisco DevNet Associate 200-901 exam, this concept tests your understanding of NSO’s reconciliation and lifecycle management features; a common trap is confusing out-of-sync with a device being unreachable or a sync failure. Remember: out-of-sync means the device has changed outside of NSO’s control, not that NSO cannot reach it. A useful memory tip is to think of “sync” as a fingerprint match—if the fingerprints don’t align, the device is out-of-sync.
200-901 Cisco Platforms and Development Practice Question
This 200-901 practice question tests your understanding of cisco platforms and development. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
Refer to the exhibit. A service engineer runs a 'check-sync' action on the NSO service 'vpn1'. The result shows 'out-of-sync' for device 'pe1'. What does this indicate?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The configuration on pe1 differs from the service model defined in NSO.
The 'check-sync' action in NSO compares the actual device configuration (retrieved via NETCONF or CLI) against the configuration that NSO's service model expects. An 'out-of-sync' result for device 'pe1' means the running configuration on pe1 does not match the configuration defined by the NSO service model for that device. This is a standard NSO feature to detect configuration drift.
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 device pe1 is unreachable via NETCONF.
Why it's wrong here
Unreachable would cause connection error, not out-of-sync.
✗
The service model in NSO does not have a configuration for pe1.
Why it's wrong here
It has, as per exhibit.
✗
The device pe1 has a hardware failure.
Why it's wrong here
Check-sync does not check hardware.
✓
The configuration on pe1 differs from the service model defined in NSO.
Why this is correct
Check-sync compares device config with service model.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is confusing 'out-of-sync' with connectivity or hardware issues; Cisco tests whether you understand that NSO's check-sync is a configuration comparison mechanism, not a reachability or health check.
Detailed technical explanation
How to think about this question
NSO uses a 'nano service' architecture where service models are mapped to device configurations via YANG models and templates. The 'check-sync' action performs a deep comparison of the device's operational state (retrieved via NETCONF <get-config> or CLI show commands) against the service's 'fast-map' or 'slow-map' generated configuration. If any leaf or list entry differs, the service is marked out-of-sync, and a 're-deploy' or 'sync-from' action is needed to reconcile the difference.
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 practitioner preparing for the 200-901 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
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.
Cisco Platforms and Development — This question tests Cisco Platforms and Development — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The configuration on pe1 differs from the service model defined in NSO. — The 'check-sync' action in NSO compares the actual device configuration (retrieved via NETCONF or CLI) against the configuration that NSO's service model expects. An 'out-of-sync' result for device 'pe1' means the running configuration on pe1 does not match the configuration defined by the NSO service model for that device. This is a standard NSO feature to detect configuration drift.
What should I do if I get this 200-901 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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Question Discussion
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