In this article, we will see 100 PromQL(Prometheus Query Language) MCQs for Interviews and Exams. Prometheus Query Language, commonly known as PromQL, is a powerful and flexible query language specifically designed for the Prometheus monitoring system. Prometheus is an open-source system monitoring and alerting toolkit, widely used for its robust metrics collection, querying capabilities, and alerting features. PromQL plays a crucial role in these functionalities. We will see 100 MCQs related to those roles and all the important functionalities it provides for prometheus monitoring system.

 

100 PromQL(Prometheus Query Language) MCQs for Interviews and Exams

Also Read: 50 Apache Kafka Interview Questions and Answers for Beginners

1. What is PromQL primarily used for?

A. Data backup
B. Querying and analyzing time-series data in Prometheus
C. Managing user permissions in Prometheus
D. Visualizing data in Grafana

Ans: B. Querying and analyzing time-series data in Prometheus

 

2. Which of the following is a basic element in PromQL?

A. Dashboard
B. Metric
C. Panel
D. Alert

Ans: B. Metric

 

3. What does a 'Counter' in PromQL represent?

A. A gauge that decreases and increases
B. A metric that only increases or resets to zero
C. A constant value
D. A dynamic query function

Ans: B. A metric that only increases or resets to zero

 

4. In PromQL, what operator would you use to select a range of time series data?

A. []
B. ()
C. {}
D. <>

Answer: A. []

 

5. What is the purpose of the 'sum' function in PromQL?

A. To count the number of elements in a series
B. To calculate the average value of a series
C. To calculate the total sum of a series
D. To determine the maximum value of a series

Ans: C. To calculate the total sum of a series

 

6. How does PromQL handle missing data in a time series?

A. By interpolating values
B. By using the last known value
C. By skipping the missing data
D. By resetting the series

Ans: C. By skipping the missing data

 

7. Which keyword in PromQL is used for specifying a time duration?

A. DURATION
B. PERIOD
C. TIME
D. FOR

Ans: D. FOR

 

8. What does the PromQL 'rate' function compute?

A. The count of events in a given time window
B. The average value over time
C. The per-second average rate of increase of a counter
D. The total sum over a specified time period

Ans: C. The per-second average rate of increase of a counter

 

 

9. In PromQL, what does a 'Histogram' typically represent?

A. A visual representation of data
B. A metric type that samples observations
C. A static metric value
D. A query function

Ans: B. A metric type that samples observations

 

10. What role do labels play in PromQL?

A. They organize queries into categories
B. They are used for aesthetic purposes
C. They identify and group time series data
D. They control access to data

Ans: C. They identify and group time series data

 

11. Which PromQL function is used to calculate the minimum value of a given range of data?

A. min_over_time
B. sum_over_time
C. avg_over_time
D. max_over_time

Ans: A. min_over_time

 

12. What is the purpose of the label_replace function in PromQL?

A. To delete labels from a metric
B. To replace an existing label's value
C. To create a new metric with different labels
D. To filter data based on label values

Ans: B. To replace an existing label's value

 

13. In PromQL, how is the irate function different from the rate function?

A. irate calculates the rate over the last two points
B. irate calculates the total rate over all points
C. irate is used for counters, rate for gauges
D. There is no difference

Ans: A. irate calculates the rate over the last two points

 

14. What type of data does the histogram_quantile function in PromQL operate on?

A. Gauge
B. Counter
C. Histogram
D. Summary

Ans: C. Histogram

 

15. Which PromQL operator allows you to perform vector matching on time series data?

A. The + operator
B. The * operator
C. The == operator
D. The on operator

Ans: D. The on operator

 

16. In PromQL, what is the purpose of using offset in a query?

A. To shift the time window of the query
B. To add an offset to metric values
C. To delay the execution of the query
D. To offset labels for grouping

Ans: A. To shift the time window of the query

 

17. What does the count function in PromQL return?

A. The total sum of all the values in a range vector
B. The average value of all points in a range vector
C. The number of elements in a range vector
D. The maximum value in a range vector

Ans: C. The number of elements in a range vector

 

18. Which PromQL function would you use to find the standard deviation of a range of values?

A. stddev_over_time
B. avg_over_time
C. variance_over_time
D. sum_over_time

Ans: A. stddev_over_time

 

19. What does a vector represent in PromQL?

A. A collection of matrices
B. A set of time series data at a single point in time
C. A database of Prometheus metrics
D. A graphical representation of data

Ans: B. A set of time series data at a single point in time

 

20. How does the absent function in PromQL work?

A. It returns 1 if the vector is empty
B. It removes absent values from the result
C. It calculates the absolute value of elements
D. It checks for non-existent labels

Ans: A. It returns 1 if the vector is empty

 

21. What result does the up metric in PromQL typically return?

A. The status of the Prometheus server
B. The number of active alerts
C. The uptime of a monitored service
D. The availability status of target instances

Ans: D. The availability status of target instances

 

22. Which function in PromQL is used to predict the value of a time series into the future?

A. predict_linear
B. future_value
C. extrapolate
D. forecast

Ans: A. predict_linear

 

23. In PromQL, how does the changes function operate?

A. It calculates the rate of change over a time period
B. It counts how many times a series has changed value
C. It identifies changes in label values
D. It adjusts for changes in metric collection intervals

Ans: B. It counts how many times a series has changed value

 

24. What does the increase function in PromQL do?

A. Calculates the increase in a counter over a time period
B. Increments all values in a series
C. Increases the time range of a query
D. Scales up the output of a query

Ans: A. Calculates the increase in a counter over a time period

 

25. Which of these is a valid PromQL aggregator?

A. join
B. merge
C. sum
D. concat

Ans: C. sum

 

26. In PromQL, what is the purpose of the without clause?

A. To exclude certain metrics from a query
B. To remove labels from the result of a query
C. To perform a query without a time range
D. To negate a query condition

Ans: B. To remove labels from the result of a query

 

27. How is the avg_over_time function used in PromQL?

A. To calculate the average value of a gauge over time
B. To average the time intervals between data points
C. To determine the average number of time series in a query
D. To compute the overall average value of a counter

Ans: A. To calculate the average value of a gauge over time

 

28. What does the holt_winters function in PromQL provide?

A. A machine learning model for anomaly detection
B. A method for linear regression analysis
C. A technique for smoothing time series data
D. A tool for historical data comparison

Ans: C. A technique for smoothing time series data

 

29. Which PromQL operator is used for vector matching based on label sets?

A. and
B. or
C. unless
D. group_left

Ans: D. group_left

 

30. What does the quantile_over_time function in PromQL do?

A. Calculates the specified quantile of values in a range vector
B. Returns the highest value in a time range
C. Determines the most frequent value in a series
D. Measures the variability of a dataset

Ans: A. Calculates the specified quantile of values in a range vector

 

31. Which PromQL function is used to find the difference between the first and last value of a range vector?

A. delta
B. diff
C. range
D. spread

Ans: A. delta

 

32. What is the role of the vector function in PromQL?

A. To convert a scalar to a vector
B. To create a vector from a string
C. To generate a vector with a single element
D. To transform a time series into a vector

Ans: A. To convert a scalar to a vector

 

33. How does the sort function affect the results of a PromQL query?

A. It orders the results by their label values
B. It arranges the output in ascending value order
C. It sorts the results based on the time of recording
D. It organizes the results in random order

Ans: B. It arranges the output in ascending value order

 

34. In PromQL, what does the group function do?

A. It aggregates multiple time series into a single series
B. It classifies time series based on label values
C. It groups results by time intervals
D. There is no group function in PromQL

Ans: D. There is no group function in PromQL

 

35. What is the primary use of the topk function in PromQL?

A. To return the top k results by sample value
B. To calculate the sum of the top k values
C. To list the top k labels in a series
D. To determine the highest k values in a time range

Ans: A. To return the top k results by sample value

 

36. How is the floor function used in PromQL?

A. To round down sample values to the nearest integer
B. To reduce the precision of floating-point values
C. To limit the query results to floor values
D. To calculate the minimum value of a series

Ans: A. To round down sample values to the nearest integer

 

37. In PromQL, what is achieved by using the bool modifier in comparison operators?

A. It turns the output into boolean values
B. It applies a Boolean logic to the query
C. It enhances the query with Boolean algebra
D. It converts numeric results into binary format

Ans: A. It turns the output into boolean values

 

38. Which PromQL function would you use to get the exact number of instant vectors in a time series?

A. count
B. count_values
C. length
D. size

Ans: A. count

 

39. What is the result of the time() function in PromQL?

A. The total time range of the query
B. The current time in Unix epoch seconds
C. The execution time of the query
D. The time interval between data points

Ans: B. The current time in Unix epoch seconds

 

40. How does the reset function in PromQL work?

A. It restarts the Prometheus server
B. It resets the time series in a query
C. It counts the number of counter resets within a time series
D. It removes all labels from a time series

Ans: C. It counts the number of counter resets within a time series

 

41. What does the PromQL function count_over_time calculate?

A. The total count of all values in a range vector
B. The number of unique label sets in a range vector
C. The average value of a range vector
D. The rate of change in a range vector

Ans: A. The total count of all values in a range vector

 

42. In PromQL, what is the purpose of the label_join function?

A. To concatenate the values of multiple labels into a single label
B. To join two different metrics based on a label
C. To create a new label from existing metric names
D. To filter out labels from a query result

Ans: A. To concatenate the values of multiple labels into a single label

 

43. How is the bottomk function used in PromQL?

A. To return the bottom k results by sample value
B. To calculate the sum of the bottom k values
C. To list the bottom k labels in a series
D. To determine the lowest k values in a time range

Ans: A. To return the bottom k results by sample value

 

44. Which PromQL function is best suited for calculating the average rate of change of a counter over time?

A. avg_over_time
B. rate
C. increase
D. delta

Ans: B. rate

 

45. In PromQL, what does the ignoring clause do in a query?

A. It disregards specific labels while matching series
B. It ignores any null or missing values in a series
C. It excludes certain metrics from the query
D. It skips the specified time range in the query

Ans: A. It disregards specific labels while matching series

 

46. What result is returned by the PromQL absent function when a series is present?

A. A vector with a single zero
B. An empty vector
C. A vector with the value '1'
D. The original series unmodified

Ans: B. An empty vector

 

47. How does the clamp_max function in PromQL operate?

A. It sets an upper limit on the query time range
B. It caps the values in a series to a maximum value
C. It finds the maximum value in a series
D. It limits the number of results returned by a query

Ans: B. It caps the values in a series to a maximum value

 

48. In PromQL, what does the operator =~ represent?

A. Equal to
B. Not equal to
C. Matches a regular expression
D. Does not match a regular expression

Ans: C. Matches a regular expression

 

49. What does the PromQL round function do?

A. Rounds values in a series to the nearest integer
B. Smoothens the peaks in a time series
C. Creates a round-robin effect in the series data
D. Rounds the time range of a query

Ans: A. Rounds values in a series to the nearest integer

 

50. Which PromQL function would be used to get the instantaneous value of a range vector at a given time?

A. instant
B. value_at_time
C. current
D. sample

Ans: B. value_at_time

 

51. What is the primary use of the or operator in PromQL?

A. To perform a logical OR operation between two vectors
B. To add two vectors together
C. To return the union of two vectors, excluding overlapping elements
D. To compare two vectors and return the larger of each pair of elements

Ans: C. To return the union of two vectors, excluding overlapping elements

 

52. How does the avg aggregator function in PromQL work?

A. It calculates the sum of values in each time series
B. It finds the maximum value in each time series
C. It computes the average of values in each time series
D. It counts the number of elements in each time series

Ans: C. It computes the average of values in each time series

 

53. Which function in PromQL is used to calculate the 90th percentile over a range vector?

A. quantile(0.9, ...)
B. topk(0.9, ...)
C. percentile(90, ...)
D. p90_over_time(...)

Ans: A. quantile(0.9, ...)

 

54. What does the min function in PromQL return?

A. The minimum value across a range of time series
B. The time series with the minimum value at each instant
C. The minimum value of each time series in a vector
D. The smallest label set in the query result

Ans: A. The minimum value across a range of time series

 

55. In PromQL, what is the unless operator used for?

A. To exclude certain time series based on a condition
B. To perform subtraction between two vectors
C. To return a vector only when another vector is absent
D. To create a default value if a query returns no result

Ans: C. To return a vector only when another vector is absent

 

56. How is the clamp_min function used in PromQL?

A. To set a lower threshold for a query
B. To return the minimum value within each time series
C. To cap the values in a series at a minimum value
D. To limit the number of elements returned in a query

Ans: C. To cap the values in a series at a minimum value

 

57. What is the result of using the * operator in PromQL without a joining criterion?

A. It multiplies the values of all matching elements
B. It returns an error
C. It performs a Cartesian product of the two vectors
D. It multiplies the values of all elements regardless of matching

Ans: C. It performs a Cartesian product of the two vectors

 

58. Which PromQL function is used to calculate the sum of all elements in a range vector?

A. total_over_time
B. sum_over_time
C. accumulate
D. aggregate_over_time

Ans: B. sum_over_time

 

59. What does the on clause in a PromQL query do?

A. Specifies the labels to match on during a vector operation
B. Sets the time range for the query
C. Indicates the metric on which to perform the query
D. Turns on specific query optimizations

Ans: A. Specifies the labels to match on during a vector operation

 

60. How is the rate function in PromQL typically used with counters?

A. To calculate the total increase of the counter over time
B. To determine the per-second average rate of increase
C. To find the instantaneous rate of change
D. To measure the frequency of counter resets

Ans: B. To determine the per-second average rate of increase

 

61. In PromQL, what is the function of the histogram_quantile function?

A. To create a histogram from a set of data
B. To calculate a quantile value from a histogram
C. To convert a histogram into a time series
D. To aggregate multiple histograms into one

Ans: B. To calculate a quantile value from a histogram

 

62. How does the sum without function operate in PromQL?

A. It sums up values while ignoring specified labels
B. It adds values without any labels
C. It returns the sum of values excluding the minimum and maximum
D. It sums up values without time constraints

Ans: A. It sums up values while ignoring specified labels

 

63. Which PromQL function is used for alerting based on the sudden change in a metric?

A. changes
B. delta
C. deriv
D. predict_linear

Ans: C. deriv

 

64. What does the idelta function in PromQL compute?

A. The integral of a time series
B. The instant rate of change between the last two samples
C. The average delta over a time period
D. The total change over the entire time series

Ans: B. The instant rate of change between the last two samples

 

65. In PromQL, what does the count by function do?

A. It counts the number of unique values for each label
B. It groups the count by a set of labels
C. It returns the total count of elements in a time series
D. It counts the number of labels in a query

Ans: B. It groups the count by a set of labels

 

66. How is the max_over_time function used in PromQL?

A. To calculate the maximum value over a specified time period
B. To find the time when the maximum value occurred
C. To determine the overall maximum value of all time series
D. To limit the time range of a query to its maximum value

Ans: A. To calculate the maximum value over a specified time period

 

67. What is the result of the avg by operation in PromQL?

A. It averages the values of each series by label
B. It calculates the global average across all series
C. It averages the values within each series
D. It returns the average number of labels

Ans: A. It averages the values of each series by label

 

68. Which PromQL operator is used to exclude some labels from the result?

A. without
B. ignore
C. excluding
D. omit

Ans: A. without

 

69. In PromQL, how does the rate function differ from the delta function?

A. rate calculates a per-second average rate, while delta calculates the absolute change
B. rate shows total increase, delta shows per-second increase
C. There is no difference between the two functions
D. delta is used for gauges, rate for counters

Ans: A. rate calculates a per-second average rate, while delta calculates the absolute change

 

70. What does the group_left modifier do in PromQL?

A. It groups the results based on the leftmost label
B. It is used in many-to-one and one-to-many matching
C. It excludes the leftmost label in a query
D. It shifts the time series data to the left

Ans: B. It is used in many-to-one and one-to-many matching

 

71. What is the purpose of the sort_desc function in PromQL?

A. To arrange query results in descending order based on their values
B. To sort labels in descending alphabetical order
C. To reverse the time range of a query
D. To calculate the descending cumulative sum of a series

Ans: A. To arrange query results in descending order based on their values

 

72. In PromQL, what does the irate function specifically measure?

A. The rate of increase over the longest possible time period
B. The instant rate of increase based on the last two data points
C. The average rate of increase over the entire time series
D. The predicted rate of increase for future values

Ans: B. The instant rate of increase based on the last two data points

 

73. How is the label_match function used in PromQL?

A. To find series that match a given label expression
B. To replace the labels of a series
C. To add new labels to a series
D. There is no label_match function in PromQL

Ans: D. There is no label_match function in PromQL

 

74. What does the year() function return in PromQL?

A. The year from each timestamp in a time series
B. The number of years since the Unix epoch
C. The current year
D. The year of the oldest data point in a series

Ans: C. The current year

 

75. In PromQL, what does the vector(scalar) function do?

A. It converts a scalar value to a vector
B. It multiplies a vector by a scalar
C. It extracts the scalar value from a vector
D. It creates a vector with elements equal to the scalar value

Ans: A. It converts a scalar value to a vector

 

76. How does the time() function in PromQL work?

A. It returns the current time in Unix time format
B. It calculates the total time span of the data in a query
C. It converts a time series into a scalar timestamp
D. It measures the time taken to execute a query

Ans: A. It returns the current time in Unix time format

 

77. What is the use of count_values in PromQL?

A. To count the number of unique values in a series
B. To count the occurrences of each value in a series
C. To sum up the values in a series
D. To find the most frequent value in a series

Ans: B. To count the occurrences of each value in a series

 

78.  In PromQL, what is the result of the sum by operation?

A. It sums the values of each series and groups the result by label
B. It sums up all values in the query regardless of labels
C. It calculates the sum of a series and then applies labels
D. It returns the sum of all labels in a series

Ans: A. It sums the values of each series and groups the result by label

 

79. How does the month() function in PromQL operate?

A. It extracts the month from each timestamp in a series
B. It returns the number of months since the Unix epoch
C. It gives the current month
D. It calculates the average values for each month

Ans: C. It gives the current month

 

80. What does the PromQL operator != accomplish?

A. It selects elements that are not equal in value
B. It finds labels that do not match
C. It negates a boolean expression
D. It excludes specific metrics from the results

Ans: A. It selects elements that are not equal in value

 

81. Which PromQL function is used to calculate the current memory usage as a percentage of the total available memory?

A. avg_over_time
B. sum
C. rate
D. percentage

Ans: D. percentage

 

82. In PromQL, what does the count_scalar function do?

A. It converts a count into a scalar value
B. It counts the number of scalar values in a vector
C. It creates a scalar from the count of elements in a vector
D. There is no count_scalar function in PromQL

Ans: D. There is no count_scalar function in PromQL

 

83. How is the exp function used in PromQL?

A. To calculate the exponential growth of a series
B. To expand the range of a query
C. To express a series in exponential format
D. To exponentiate each value in a series

Ans: D. To exponentiate each value in a series

 

84. What does the offset modifier do in a PromQL query?

A. It shifts the time series back by a specified duration
B. It adds a fixed value to each data point
C. It adjusts the starting point of the query
D. It offsets the value of labels in a query

Ans: A. It shifts the time series back by a specified duration

 

85. In PromQL, what is the result of the ln function?

A. It calculates the natural logarithm of each value in a series
B. It returns a linear interpolation of a time series
C. It links two time series together
D. It finds the line number of each data point

Ans: A. It calculates the natural logarithm of each value in a series

 

86. How does the quantile function work in PromQL?

A. It determines the specified quantile across input vectors
B. It creates a quantile series from a single vector
C. It quantifies the difference between two vectors
D. It returns a vector containing all quantiles

Ans: A. It determines the specified quantile across input vectors

 

87. What is the purpose of the stddev function in PromQL?

A. To standardize the deviance of a time series
B. To calculate the standard deviation within each time series
C. To find deviations from the standard values
D. To normalize the standard labels in a query

Ans: B. To calculate the standard deviation within each time series

 

88. In PromQL, how is the year function typically used?

A. To filter data by year
B. To extract the year from a timestamp
C. To calculate the yearly rate of change
D. To group data by year

Ans: B. To extract the year from a timestamp

 

89. What does the avg without function do in PromQL?

A. It averages values while ignoring specified labels
B. It computes the average without considering time range
C. It calculates the average excluding minimum and maximum values
D. It averages values without any labels

Ans: A. It averages values while ignoring specified labels

 

90. In PromQL, what does the predict_linear function estimate?

A. The future value of a time series based on past trends
B. Linear correlations between two time series
C. The linear progression of label values
D. The linear increase rate of a counter

Ans: A. The future value of a time series based on past trends

 

91. What is the primary function of the increase function in PromQL?

A. To calculate the rate of increase of a counter over a time range
B. To sum the increases in a time series
C. To increment all values in a vector
D. To track the cumulative increase of a gauge

Ans: B. To sum the increases in a time series

 

92. In PromQL, how is the sum by (label) function used?

A. To sum up the values in each series, grouped by the specified label
B. To add values to a series based on label criteria
C. To sum all values across different series without grouping
D. To add a new label with the sum of values to each series

Ans: A. To sum up the values in each series, grouped by the specified label

 

93. Which function in PromQL is best suited for finding the highest value of a metric over a specified time range?

A. max
B. max_over_time
C. topk
D. highest

Ans: B. max_over_time

 

94. How does the absent function operate in PromQL?

A. It removes absent values from a series
B. It returns a vector if the input vector is empty
C. It checks for the absence of a specified label
D. It creates an empty vector from a non-empty input

Ans: B. It returns a vector if the input vector is empty

 

95. What does the histogram_quantile function compute in PromQL?

A. The distribution of values in a histogram
B. The average value of a histogram
C. A quantile value from a histogram
D. The sum of all buckets in a histogram

Ans: C) A quantile value from a histogram

 

96. In PromQL, what is the purpose of the rate function when used with counter metrics?

A. To calculate the total increase of the counter
B. To find the average value of the counter
C. To determine the per-second average rate of increase
D. To measure the instantaneous rate of change

Ans: C. To determine the per-second average rate of increase

 

97. How is the floor function used in PromQL?

A. To reduce the precision of floating-point values
B. To round down each value in a series to the nearest integer
C. To find the minimum value of a series
D. To set a lower limit for query results

Ans: B. To round down each value in a series to the nearest integer

 

98. What result does the group_left modifier yield in PromQL vector matching?

A. It groups the leftmost labels in a query
B. It is used in many-to-one and one-to-many matches
C. It excludes the leftmost label in vector matching
D. It performs a left join of two vectors

Ans: B. It is used in many-to-one and one-to-many matches

 

99. In PromQL, how does the count_over_time function operate?

A. It counts the number of unique values over time
B. It sums up the count of all elements in a range vector
C. It counts the occurrences of a specific value over time
D. It calculates the rate of count increase over time

Ans: B) It sums up the count of all elements in a range vector

 

100. In PromQL, what does the vector function do?

A. It converts a scalar or string to a vector
B. It creates a vector from a time series
C. It transforms a range vector into an instant vector
D. It generates a vector with all elements set to a specific value

Ans: A. It converts a scalar or string to a vector