200-901 Cisco Platforms and Development Practice Question
This 200-901 practice question tests your understanding of cisco platforms and development. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 network developer is using Cisco NSO to manage multi-vendor devices. Which three are valid approaches to handle device-specific differences? (Choose three.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Write custom Python code in the service model
Option A is correct because Cisco NSO allows developers to write custom Python code within the service model to handle device-specific logic, such as translating abstract service parameters into vendor-specific CLI or NETCONF commands. This approach provides flexibility to accommodate non-standard configurations that cannot be expressed purely through YANG models or NEDs.
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.
✓
Write custom Python code in the service model
Why this is correct
Python callbacks can implement vendor-specific logic.
Related concept
Read the scenario before looking for a memorised answer.
✓
Use YANG data models to abstract device specifics
Why this is correct
YANG models provide a vendor-neutral data representation.
Related concept
Read the scenario before looking for a memorised answer.
Use NEDs (Network Element Drivers) for each vendor
Why this is correct
NEDs translate between NSO and device CLI.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that SNMP MIBs are a primary tool for configuration management in NSO, when in fact NSO uses NEDs and YANG models for configuration abstraction, and SNMP is typically limited to read-only monitoring.
Detailed technical explanation
How to think about this question
Under the hood, NSO uses a combination of YANG data models to define a unified service abstraction and NEDs to translate that abstraction into device-native protocols (e.g., NETCONF, CLI, SNMP). Custom Python code in the service model can invoke NSO's MAAPI or CDB APIs to perform complex transformations or conditional logic, such as mapping a single service parameter to different CLI commands across Cisco IOS and Juniper Junos devices. In a real-world scenario, a developer might use Python to handle a vendor-specific feature like VRF configuration that differs in syntax between devices, ensuring the service model remains vendor-agnostic.
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: Write custom Python code in the service model — Option A is correct because Cisco NSO allows developers to write custom Python code within the service model to handle device-specific logic, such as translating abstract service parameters into vendor-specific CLI or NETCONF commands. This approach provides flexibility to accommodate non-standard configurations that cannot be expressed purely through YANG models or NEDs.
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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