200-901 Understanding and Using APIs Practice Question
A developer is writing a Python script that calls the Cisco Webex API. The script must handle the case where the API returns a 429 Too Many Requests response. Which HTTP response header should the script inspect to determine how long to wait before retrying the request?
⚠ Common exam trap
The trap here is assuming any rate-limit-related header such as X-RateLimit-Limit or X-RateLimit-Remaining tells you how long to wait, when only Retry-After conveys the backoff duration.
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
✓
Retry-After
When a REST API throttles a client with 429 Too Many Requests, the standard way to communicate the required backoff is the Retry-After response header, which contains either a number of seconds or an HTTP date. Cisco Webex returns this header, so a well-behaved client reads it and delays the next attempt accordingly, rather than retrying immediately and remaining throttled.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
X-RateLimit-Limit
Why it's wrong here
X-RateLimit-Limit indicates the maximum number of requests allowed in the current time window, not how long the client must wait after exceeding it. Inspecting this value tells the developer the quota size but does not provide the delay needed to recover from a 429, so retrying based on it could immediately trigger another rejection.
- ✗
Cache-Control
Why it's wrong here
Cache-Control governs how responses may be cached by clients and intermediaries, including directives like no-store or max-age. It has no role in rate limiting or retry timing, so reading it after a 429 would not tell the script when the throttle window resets or when a subsequent request is likely to succeed.
- ✓
Retry-After
Why this is correct
The Retry-After header is the standard HTTP mechanism for a server to tell a client how many seconds to wait before making another request. Cisco Webex APIs return this header on 429 responses, so the script should read its value and sleep for that duration before retrying, avoiding further throttling and potential temporary blocking.
- ✗
Link
Why it's wrong here
The Link header is used for pagination, providing URLs for the next, previous, first, or last page of a collection. It carries no timing information, so a script that inspects Link after a 429 would find no guidance on how long to pause, and immediate retries would keep hitting the rate limit.
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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
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.