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200-901 Practice Question: A developer is designing a REST API for managing…
A developer is designing a REST API for managing network devices. The API should support idempotent operations for updating device configuration. Which HTTP method should be used for the update operation?
⚠ Common exam trap
Cisco often tests the distinction between PUT and PATCH by emphasizing idempotency, leading candidates to mistakenly choose PATCH because it is commonly used for updates, but PATCH is not inherently idempotent.
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
✓
PUT
PUT is the correct HTTP method for idempotent updates because it replaces the entire resource at a given URI with the request body. Idempotency means that multiple identical PUT requests produce the same result as a single request, which is essential for safely retrying configuration updates without side effects. This aligns with RFC 7231, which defines PUT as idempotent.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
DELETE
Why it's wrong here
DELETE removes a resource and is idempotent, but it cannot update device configuration. It tempts because idempotency is the stated requirement, yet DELETE satisfies that by deleting the target rather than replacing its configuration; PUT performs the idempotent update.
- ✓
PUT
Why this is correct
PUT replaces the target resource entirely with the enclosed representation, so repeating an identical request leaves the device configuration unchanged — satisfying the idempotency constraint in the stem. Unlike POST, which may create or append on each call, PUT's full-replacement semantics guarantee safe retries after network timeouts.
- ✗
PATCH
Why it's wrong here
PATCH applies a partial modification and is not guaranteed idempotent, so repeated identical requests can yield different results. It tempts because it updates resources, but the stem demands idempotent full configuration replacement, which PUT provides by overwriting the resource.
- ✗
POST
Why it's wrong here
POST is neither idempotent nor safe; repeating it can create duplicate resources or reapply changes. It tempts because it submits data to the server, but the stem requires idempotent update of an existing device configuration, which PUT achieves by replacing the resource.
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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.