PCA Promql Practice Question
An operator needs to find the rate of change of a counter using deriv(). Why is this considered a bad practice in Prometheus?
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
✓
deriv() does not account for counter resets, causing massive negative drops when counters reset.
deriv() is designed for linear regression on gauge metrics over range vectors and does not handle counter resets, leading to incorrect downward spikes when counters reset.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
deriv() does not account for counter resets, causing massive negative drops when counters reset.
Why this is correct
Correct. deriv() treats counters as gauges and fails on resets.
- ✗
deriv() automatically multiplies output by an undocumented scaling factor.
Why it's wrong here
It does not multiply by a secret scaling factor.
- ✗
deriv() requires native histograms, which are incompatible with standard counters.
Why it's wrong here
deriv() is unrelated to native histograms.
- ✗
deriv() only works with scalar values and rejects time series vectors.
Why it's wrong here
deriv() accepts range vectors of time series.
About these practice questions
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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.