PCA Promql Practice Question
When calculating the 95th percentile from a histogram, why is histogram_quantile(0.95, sum(rate(http_duration_seconds_bucket[5m])) by (le)) the recommended 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
✓
Aggregating by 'le' keeps the bucket boundaries intact for the quantile calculation.
Aggregation must occur before the quantile calculation to ensure all buckets are summed across labels.
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 0.95 argument requires the 'le' label to be removed.
Why it's wrong here
The 'le' label is required for the function to map values to buckets.
- ✓
Aggregating by 'le' keeps the bucket boundaries intact for the quantile calculation.
Why this is correct
Summing by the 'le' label merges distributions while preserving the necessary bucket structure.
- ✗
The rate function cannot be used inside histogram_quantile.
Why it's wrong here
rate is required to convert raw buckets into a rate of events.
- ✗
It is faster than calculating the quantile per instance.
Why it's wrong here
Performance is a secondary benefit to correctness.
About these practice questions
One of 304 original PCA practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. 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.