PCA Promql Practice Question
A Prometheus administrator wants to query the current value of the metric 'http_requests_total'. Which of the following PromQL expressions should be used?
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
✓
http_requests_total
An instant vector selector like 'http_requests_total' queries the current value (instant vector) of a metric. Range vectors require a duration in brackets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
http_requests_total[5m]
Why it's wrong here
This is a range vector selector, which is invalid for direct graphing without a range-to-instant function like rate().
- ✓
http_requests_total
Why this is correct
This is an instant vector selector, returning the most recent sample for each time series.
- ✗
rate(http_requests_total)
Why it's wrong here
The rate() function requires a range vector argument, not an instant vector.
- ✗
sum(http_requests_total) over (instance)
Why it's wrong here
The 'over' keyword is invalid syntax in PromQL.
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.