200-901 Software Development and Design Practice Question
A developer uses the requests library to call an API. The API returns 429 Too Many Requests. What is the best practice to handle this?
⚠ Common exam trap
The trap is choosing 'immediately retry' or 'fixed wait' as simpler alternatives — candidates underestimate how retry storms amplify server load and overlook exponential backoff as the standard resilience pattern.
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 exponential backoff and retry
HTTP 429 Too Many Requests indicates the client has exceeded the server's rate limit. The correct handling is to retry after a delay, and exponential backoff (with jitter) is the industry best practice because it progressively increases wait times between retries, reducing load on the server and avoiding thundering-herd effects. Many APIs also return a Retry-After header that should be honored.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Ignore the status code and proceed
Why it's wrong here
Ignoring the 429 leaves the request unretried and the rate limit unresolved, so the call simply fails. It is tempting when a script tolerates occasional errors, but ignoring status codes suits only idempotent fire-and-forget logging where no response data is needed.
- ✗
Immediately retry the request
Why it's wrong here
Retrying instantly ignores the server's rate-limit signal, so the same throttling recurs and may extend the block. It is tempting because transient errors often clear on a quick retry, but 429 requires honouring the Retry-After header or applying exponential backoff before resending.
- ✓
Use exponential backoff and retry
Why this is correct
HTTP 429 signals rate limiting, so retrying immediately would worsen the condition. Exponential backoff progressively increases the delay between retries, satisfying the stem's best-practice requirement by giving the server time to recover while respecting its rate limits.
- ✗
Wait a fixed amount of time and retry
Why it's wrong here
A fixed delay disregards the Retry-After header the server supplies, so the retry may still fall inside the throttling window. Fixed waits suit predictable transient faults, whereas 429 demands backoff aligned to the server's stated interval, ideally with jitter.
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JA
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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