easyMultiple Choice
200-901 Practice Question: A developer is building a dashboard that displays…
A developer is building a dashboard that displays the health status of network devices managed by Cisco ACI. The developer uses the ACI REST API to query the APIC (Application Policy Infrastructure Controller). The developer sends a GET request to https://apic-ip/api/class/fabricHealthInst.json returns a JSON object with health scores. The dashboard works for a small set of devices, but when scaled to 500 devices, the API responses become slower and sometimes time out. The developer needs to optimize the data retrieval to keep the dashboard responsive. Which approach should the developer use?
⚠ Common exam trap
Cisco often tests the distinction between polling (synchronous GET requests) and event-driven subscriptions (asynchronous push) to evaluate understanding of API optimization patterns, and the trap here is that candidates mistakenly think breaking requests into smaller chunks or changing languages will solve scalability issues, when the real solution is to avoid unnecessary data retrieval altogether.
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
✓
Use the ACI event subscription mechanism to receive health updates only when changes occur.
The ACI REST API supports an event subscription mechanism (e.g., WebSocket-based subscriptions) that pushes updates only when the health score of a device changes, rather than requiring the dashboard to poll the APIC repeatedly. This drastically reduces network overhead and server load, especially when scaling to 500 devices, as it eliminates the need for frequent full GET requests to /api/class/fabricHealthInst.json.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Break the request into multiple smaller requests, each fetching a subset of devices.
Why it's wrong here
Splitting the query increases the number of round trips to the APIC, and each request still returns the same total dataset, so latency and timeout risk worsen. Pagination is the right pattern when an API caps page size, but here the goal is reducing payload volume per call, which a filtered, class-scoped query achieves.
- ✗
Add a query parameter to sort the results by health score to reduce processing time.
Why it's wrong here
Sorting by health score reorders the full result set after the APIC has already gathered and serialised every object, so response size and processing time are unchanged. Sorting suits client-side ranking of a small result set, but it does not reduce the volume that causes the timeouts.
- ✗
Switch from JavaScript to Python for the backend to handle larger responses more efficiently.
Why it's wrong here
Changing backend language alters neither the APIC's response payload nor its server-side processing, so the timeout persists. Python is a reasonable choice when a team needs specific libraries or concurrency models, but the bottleneck is the volume returned per request, not the language parsing it.
- ✓
Use the ACI event subscription mechanism to receive health updates only when changes occur.
Why this is correct
Event subscriptions push health updates only when state changes, eliminating repeated polling of 500 devices that saturates APIC and causes timeouts. Unlike GET queries returning full class objects each time, subscriptions use websockets or callbacks, so the dashboard stays responsive under scale while satisfying the requirement to optimise retrieval latency.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-901 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 200-901 exam.