PCA Promql Practice Question
An operator needs to query the current, un-extrapolated rate of increase per second over the last 5 minutes for a counter metric named http_requests_total. Which function should they use?
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
✓
irate(http_requests_total[5m])
The irate() function calculates the per-second rate of increase of a time series based on the last two data points in the specified range window, making it ideal for volatile, high-frequency counters.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
increase(http_requests_total[5m])
Why it's wrong here
increase returns the total absolute increase over the range window, not a per-second rate.
- ✓
irate(http_requests_total[5m])
Why this is correct
Correct because irate calculates the per-second instant rate based on the last two points.
- ✗
rate(http_requests_total[5m])
Why it's wrong here
rate calculates the average per-second rate over the whole window, including extrapolation.
- ✗
delta(http_requests_total[5m])
Why it's wrong here
delta is intended for gauge metrics, not counters.
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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.