PCA Metric Collection & Data Modeling 3

Question 1

What does the `quantile` label represent in a Prometheus Summary metric?

Accepted Answer

A pre-calculated percentile value over a sliding time window

Answer

The `quantile` label in a Summary represents a pre-calculated percentile (e.g., 0.95) computed client-side over a configurable sliding window.

Question 2

A Pushgateway metric has a `job` label that conflicts with the scrape target's `job` label. What happens by default?

Accepted Answer

The pushed metric's label is preserved and the target's is renamed with `exported_` prefix

Answer

When label conflicts occur during scraping, Prometheus prefixes the conflicting scraped label with `exported_` and keeps the pushed metric's label.

Question 3

Which function correctly calculates the per-second rate of increase of a counter over the last 5 minutes, accounting for resets?

Accepted Answer

rate(metric[5m])

Answer

`rate()` computes the per-second average rate of increase over the specified range, handling counter resets automatically.

Question 4

In the Prometheus data model, what uniquely identifies a time series?

Accepted Answer

The metric name plus its set of label name-value pairs

Answer

A Prometheus time series is uniquely identified by the combination of its metric name and the complete set of label name-value pairs.

Question 5

What is the primary difference between `rate()` and `irate()` in Prometheus?

Accepted Answer

`rate()` averages over the full range while `irate()` uses only the last two data points

Answer

`irate()` calculates the instantaneous rate using only the last two data points, making it more responsive to spikes but noisier than `rate()`.

(PCA) Prometheus Certified Associate Practice Test