200-901 Understanding and Using APIs Practice Question
A developer's script calls a REST API and receives HTTP 429 Too Many Requests. The response includes a Retry-After header with a value of 30. What should the script do to behave correctly?
⚠ Common exam trap
The trap here is treating 429 like a permanent 4xx client error instead of a transient throttling response that should be retried after the indicated delay.
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
✓
Wait at least 30 seconds, then retry the request.
A 429 response signals that the client has exceeded a rate limit, and the accompanying Retry-After header states how long to wait before retrying. Pausing for that interval respects the server's throttling policy and avoids worsening the condition. Immediate retries, method changes, or permanently aborting all fail to follow the server's explicit guidance.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Immediately resend the identical request in a tight loop until it succeeds.
Why it's wrong here
Retrying instantly ignores the server's rate-limit signal and typically deepens the problem. The Retry-After value exists precisely to tell the client how long to wait. A tight loop can consume the remaining quota, trigger longer lockouts, and waste API calls, so it is the opposite of correct rate-limit handling.
- ✗
Change the HTTP method from GET to POST and resend.
Why it's wrong here
The status code reflects request volume, not the verb used. Switching methods does not reset the rate counter and may create or modify resources unintentionally. The 429 will likely recur, and the client may also produce duplicate side effects, making this a harmful response to throttling.
- ✗
Treat the response as a permanent failure and stop all further API calls.
Why it's wrong here
429 is a transient, retryable condition rather than a permanent error like 403 or 404. Abandoning the workflow permanently discards work that could succeed after a short delay. Proper clients back off according to Retry-After and continue, so halting everything is an overreaction.
- ✓
Wait at least 30 seconds, then retry the request.
Why this is correct
HTTP 429 means the client exceeded an allowed request rate. The Retry-After header communicates how many seconds to pause before trying again. Honoring that value lets the server's rate window reset and gives the retry a realistic chance of success, which is the behavior API providers expect from well-behaved clients.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
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