mediumMultiple Select
200-901 Practice Question: A developer receives HTTP 409 Conflict when…
A developer receives HTTP 409 Conflict when updating a network configuration via Cisco NX-OS API. Which two scenarios could cause this error?
⚠ Common exam trap
Cisco often tests the distinction between client-side errors (400, 401) and server-side state conflicts (409), so the trap here is confusing a malformed request or authentication failure with a resource state conflict.
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 resource was recently modified by another client.
Option A is correct because HTTP 409 Conflict is returned when the target resource's state has changed since the client last read it, typically due to a concurrent modification by another client, so the update cannot be applied against the stale representation. Option B is correct because NX-OS API transactions can hold locks on configuration resources, and attempting to update a resource locked by another transaction produces a 409 Conflict indicating the request conflicts with the current state of the resource. Option C is not correct because malformed JSON causes a 400 Bad Request, as the server cannot parse the payload. Option D is not correct because unsupported parameters typically yield a 400 Bad Request or 422 Unprocessable Entity, not a 409. Option E is not correct because an invalid API key results in 401 Unauthorized (or 403 Forbidden), which is an authentication/authorization failure rather than a resource-state conflict.
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 resource was recently modified by another client.
Why this is correct
A concurrent write by another client triggers HTTP 409 Conflict because NX-OS detects a stale configuration revision, rejecting the update to prevent overwriting newer changes. This satisfies the stem's requirement for a scenario causing the conflict, since the resource's version no longer matches the client's submitted payload.
- ✓
The update conflicts with a lock held by another transaction.
Why this is correct
A concurrent transaction holds a configuration lock, so NX-OS rejects the write with HTTP 409 rather than queuing it. The API surfaces the conflict immediately because the candidate configuration cannot be modified while another session owns the lock, satisfying the stem's requirement for a scenario producing this status.
- ✗
The request body contains malformed JSON.
Why it's wrong here
Malformed JSON produces HTTP 400 Bad Request, as the payload fails parsing before any state comparison occurs. It is tempting because both indicate a faulty client request, but 409 requires syntactically valid input that conflicts with the device's current configuration state.
- ✗
The request includes unsupported parameters.
Why it's wrong here
Unsupported parameters typically yield HTTP 400 Bad Request, since the API rejects malformed or unknown fields during schema validation. A 409 Conflict signals a state clash, such as editing an object whose configuration revision no longer matches. This option is tempting because parameter errors are common API faults, but they map to 400, not 409.
- ✗
The API key used is invalid.
Why it's wrong here
An invalid API key yields HTTP 401 Unauthorized, since authentication fails before the request reaches conflict detection. It is tempting because both are client-side errors, but 409 signals a state conflict such as a duplicate object or a concurrent modification.
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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.