PCA Promql Practice Question
An engineer executes topk(3, http_requests_total). What happens if there are fewer than 3 time series matching the selector?
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
✓
It returns all available time series without padding or error.
If an instant vector has fewer elements than $k$, topk returns all available elements in the vector without error.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
It returns all available time series without padding or error.
Why this is correct
Correct. topk returns up to k elements if fewer exist.
- ✗
It pads the remaining slots with synthetic time series valued at 0.
Why it's wrong here
topk does not create synthetic time series.
- ✗
It returns NaN for the missing slots.
Why it's wrong here
It simply returns the smaller set of series.
- ✗
It returns an evaluation error indicating insufficient time series.
Why it's wrong here
PromQL aggregations like topk gracefully handle vectors with fewer than k items.
About these practice questions
This PCA question is part of Courseiva's 304-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official CNCF / Linux Foundation exam blueprint
This PCA practice question is part of Courseiva's free CNCF / Linux Foundation 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 PCA exam.