PCA Querying & Visualization 5

Question 1

What is the correct PromQL syntax for a subquery that evaluates `rate(http_requests_total[5m])` over the last 1 hour at 1-minute resolution?

Accepted Answer

`rate(http_requests_total[5m])[1h:1m]`

Answer

Subquery syntax appends `[range:resolution]` to a range expression, so `[1h:1m]` evaluates the inner expression over 1 hour at 1-minute steps.

Question 2

How does the `offset` modifier affect a PromQL query like `http_requests_total offset 1h`?

Accepted Answer

It retrieves the metric value as it was 1 hour ago

Answer

The `offset` modifier shifts the query's evaluation point backward in time, so `offset 1h` returns the value the metric had 1 hour ago.

Question 3

What is the recommended naming convention for a recording rule that pre-computes `sum(rate(http_requests_total[5m])) by (job)`?

Accepted Answer

`job:http_requests_total:rate5m`

Answer

Prometheus recommends the naming pattern `level:metric:operations` for recording rules, where level is the aggregation label, metric is the base metric, and operations describe the transformations applied.

Question 4

What does Prometheus do when it encounters a 'stale marker' for a time series?

Accepted Answer

It marks the series as stale and stops returning it in queries after the staleness window

Answer

Prometheus sends stale markers when a target disappears, causing the series to be marked stale and excluded from query results after the staleness period (default 5 minutes).

Question 5

What is the purpose of the `resets()` function in PromQL?

Accepted Answer

Returns the number of counter resets (value drops) within the range window

Answer

`resets(v range-vector)` returns the number of times the counter reset (decreased) within the specified range, useful for detecting service restarts.

(PCA) Prometheus Certified Associate Practice Test

(PCA) Prometheus Certified Associate Practice Test

PCA Querying & Visualization 5