PCA Promql Practice Test 5 — 15 Questions

Question 1

Which THREE of the following functions can be used with counter metrics to calculate rates or increases? (Choose three)

Accepted Answer

irate(). Counters can be used with rate(), irate(), and increase() functions (among others like delta() for gauges, though delta is technically for gauges, increase is for counters).

Answer

predict_linear()

Answer

deriv()

Question 2

When performing vector matching between two vectors of different cardinalities, which THREE vector matching modifiers can be used? (Choose three)

Accepted Answer

on. PromQL vector matching modifiers include on, ignoring, group_left, and group_right.

Answer

group_by

Answer

match_any

Question 3

Which THREE built-in functions in PromQL are designed specifically to analyze changes over time for gauge metrics? (Choose three)

Accepted Answer

delta(). Functions like delta(), deriv(), and predict_linear() (as well as idelta) operate on gauges over range vectors.

Answer

rate()

Answer

increase()

Question 4

Which THREE aggregation operators in PromQL support the 'by' and 'without' clause modifiers? (Choose three)

Accepted Answer

sum. Most PromQL aggregators support grouping clauses. Examples include sum, avg, min, max, count, stddev, stdvar, bottomk, topk, quantile.

Answer

histogram_quantile

Answer

label_replace

Question 5

Which TWO of the following statements regarding PromQL subqueries are correct? (Choose two)

Accepted Answer

Subqueries allow instant vector queries to be passed as range vector inputs to functions like max_over_time().. Subqueries allow running an instant vector query over a historical time range with a specified resolution and lookback delta.

Answer

Subqueries execute faster than standard instant queries because they bypass the storage engine.

Answer

Subqueries can only be executed against range vectors, never instant vectors.

Answer

The resolution parameter in a subquery is mandatory.

Question 6

Which TWO of the following are valid ways to modify or add labels to time series in PromQL? (Choose two)

Accepted Answer

label_replace(). PromQL provides label_replace and label_join to modify and construct labels dynamically.

Answer

label_update()

Answer

label_drop()

Answer

label_add()

Question 7

What is the result of applying a range selector like [5m] to a gauge metric?

Accepted Answer

A range vector containing all data points from the last 5 minutes.. A range selector converts an instant vector into a range vector, containing all samples in that window.

Answer

A scalar value representing the sum.

Answer

An instant vector of the average over 5 minutes.

Answer

An error, because gauges are not time-series.

Question 8

You need to calculate the per-second rate of increase for a counter metric over the last 10 minutes. Which function is most appropriate?

Accepted Answer

rate(metric[10m]). rate() is the standard function for calculating the per-second rate of increase over a range vector.

Answer

increase(metric[10m])

Answer

irate(metric[10m])

Answer

delta(metric[10m])

Question 9

Which operator has the highest precedence in PromQL?

Accepted Answer

Exponentiation (^). PromQL operator precedence follows standard mathematical rules: ^ > *, /, %, +, -.

Answer

Logical OR (or)

Answer

Addition (+)

Answer

Equality (==)

Question 10

When calculating the 95th percentile from a histogram, why is histogram_quantile(0.95, sum(rate(http_duration_seconds_bucket[5m])) by (le)) the recommended pattern?

Accepted Answer

Aggregating by 'le' keeps the bucket boundaries intact for the quantile calculation.. Aggregation must occur before the quantile calculation to ensure all buckets are summed across labels.

Answer

The 0.95 argument requires the 'le' label to be removed.

Answer

The rate function cannot be used inside histogram_quantile.

Answer

It is faster than calculating the quantile per instance.

Question 11

What is the purpose of the 'offset' modifier in a PromQL query?

Accepted Answer

To change the time range of a query to a point in the past.. The 'offset' modifier allows querying data from the past relative to the current time.

Answer

To remove specific label dimensions.

Answer

To filter out noise from the last 5 minutes.

Answer

To increase the precision of a rate calculation.

Question 12

Which aggregation operator would you use to calculate the total sum of a metric across all instances?

Accepted Answer

sum(). sum() is the standard operator for calculating totals across dimensions.

Answer

avg_over_time()

Answer

total()

Answer

count()

Question 13

When using 'irate', what is the impact of choosing a range vector that is too small (e.g., [10s])?

Accepted Answer

It captures high-frequency spikes but can be volatile.. irate only looks at the last two data points in the range; if the range is too small, it might miss changes.

Answer

It returns an error if no data points are found.

Answer

The result becomes a scalar.

Answer

The value is capped at 1.

Question 14

What is the difference between 'count' and 'count_values'?

Accepted Answer

count returns the number of series; count_values returns the frequency of values.. count aggregates by number of series, while count_values counts the number of occurrences of each sample value.

Answer

count_values is faster.

Answer

count is for gauges; count_values is for counters.

Answer

There is no difference.

Question 15

If you perform 'A / B' where A and B have different sets of labels, what happens?

Accepted Answer

It returns an empty result.. Binary operations require matching labels unless modifiers are used; otherwise, the result is empty.

Answer

It automatically ignores the extra labels.

Answer

It returns the result of the division for all series.

Answer

It returns an error in the UI.