Generative AI Leader Google Cloud's Generative AI Offerings Practice Question
A developer is using the Vertex AI PaLM API and receives a 429 Resource Exhausted error. What is the most likely cause?
⚠ Common exam trap
Generative AI Leader often tests the mapping between HTTP status codes and their causes, and candidates frequently confuse 429 (rate/quota) with 400 (bad request) or 403 (permission), leading them to pick payload-size or API-key options.
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 user has exceeded the allowed number of requests per minute
HTTP 429 Resource Exhausted is the standard error returned when a client exceeds the rate limits or quota assigned to the API — most commonly the requests-per-minute (RPM) limit. In the Vertex AI PaLM API, each project has per-minute quotas for prediction requests, and exceeding them triggers this error. The correct remediation is to implement exponential backoff and/or request a quota increase.
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 request payload is too large
Why it's wrong here
An oversized payload returns 400 Invalid Argument or 413 Payload Too Large, as request validation fails before quota accounting. It is tempting because payload limits do cause request failures, and reducing request size would be correct when the error explicitly cites a token or size limit rather than rate exhaustion.
- ✓
The user has exceeded the allowed number of requests per minute
Why this is correct
The 429 Resource Exhausted status signals quota exhaustion on the Vertex AI PaLM endpoint. Per-minute request quotas cap how many calls a project may issue; exceeding that rate triggers this error, so the cause is too many requests within the minute window.
- ✗
The model is not available in the current region
Why it's wrong here
An unavailable model in the region returns 404 Not Found or an unsupported-location error, since the endpoint itself does not exist there. It is tempting because regional availability genuinely blocks PaLM API calls, and verifying region support would be correct when the error names an unknown model or location.
- ✗
The API key is invalid
Why it's wrong here
An invalid API key returns 401 Unauthorized or 403 Permission Denied, not 429, because authentication fails before any quota is evaluated. It is tempting because credential problems are common, and checking the key would be correct when the error indicates authentication or authorisation failure rather than exhausted quota.
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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 Google Cloud exam blueprint
This Generative AI Leader practice question is part of Courseiva's free Google Cloud 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 Generative AI Leader exam.