PCA Instrumentation And Exporters Practice Test 2 — 15 Questions

Question 1

You need to expose metrics from a legacy application that only logs to a file. What should you do?

Accepted Answer

Use the node_exporter textfile collector. The node_exporter textfile collector is designed to read metrics from a specific directory where you can drop files containing Prometheus-formatted data.

Answer

None of the above

Answer

Use a blackbox exporter

Answer

Use Pushgateway

Answer

Use a custom exporter

Question 2

What is the purpose of the 'le' label in a Histogram?

Accepted Answer

Less than or equal to. The 'le' label stands for 'less than or equal to' and defines the upper bound of the histogram bucket.

Answer

Latency estimate

Answer

Logarithmic exponent

Answer

Last entry

Question 3

When creating a custom exporter, which component is responsible for scraping the data?

Accepted Answer

The Prometheus server. The Prometheus server is responsible for initiating the scrape request to the exporter.

Answer

The Pushgateway

Answer

The exporter itself

Answer

The client library

Question 4

When using the Pushgateway, what happens if you push a metric with the same name and labels as an existing one?

Accepted Answer

It overwrites the old value. The Pushgateway overwrites the existing metric with the new value provided in the push request.

Answer

It creates a new series

Answer

It rejects the push

Answer

It adds to the existing value

Question 5

What is the impact of naming a metric starting with an underscore?

Accepted Answer

Reserved for internal use. Metric names starting with underscores are reserved for internal use by Prometheus and should be avoided for user-defined metrics.

Answer

Automatic aggregation

Answer

Performance loss

Answer

Syntax error

Question 6

When using the Prometheus Go client, what is the difference between a Gauge and a GaugeVec?

Accepted Answer

GaugeVec supports labels. A Gauge represents a single value, whereas a GaugeVec allows you to have multiple gauges identified by a set of variable labels.

Answer

Gauge is faster

Answer

GaugeVec is for Histograms

Answer

There is no difference

Question 7

You notice your custom exporter is timing out during scraping. What is the most likely cause?

Accepted Answer

The scrape timeout is too short. If the exporter is overloaded or generating a massive amount of data, the scrape_timeout value in Prometheus might be too low.

Answer

The metric type is wrong

Answer

The port is blocked

Answer

The label names are incorrect

Question 8

Which of the following is a correct unit suffix for Prometheus metrics?

Accepted Answer

_seconds. Prometheus recommends using base units (e.g., seconds for duration, bytes for memory) and appending the unit to the name.

Answer

_total

Answer

_sum

Answer

_count

Question 9

What is the primary function of the 'blackbox_exporter' in a monitoring architecture?

Accepted Answer

Endpoint probing. It allows monitoring of endpoints from the outside (blackbox perspective) rather than the inside (whitebox instrumentation).

Answer

Database performance

Answer

Log aggregation

Answer

Hardware monitoring

Question 10

What is the purpose of the 'instance' label in Prometheus?

Accepted Answer

To identify the target. It is an automatically added label that identifies the target (host:port) that the metric was scraped from.

Answer

To filter alerts

Answer

To identify the user

Answer

To identify the job

Question 11

When configuring a custom exporter, how do you provide labels to a metric?

Accepted Answer

By passing a label dictionary. Labels are passed as a dictionary or map when creating the metric object in the client library.

Answer

In the scrape config

Answer

Through a config file

Answer

Via environment variables

Question 12

You are seeing 'NaN' values in your gauge metrics. What does this indicate?

Accepted Answer

An undefined gauge state. NaN (Not a Number) is a valid value for gauges in Prometheus, often indicating that a value is currently undefined or not applicable.

Answer

A scrape error

Answer

Metric type mismatch

Answer

Label collision

Question 13

Which metric type is most appropriate for tracking the current total number of active user sessions?

Accepted Answer

Gauge. Since the count of active sessions can rise and fall, a gauge is the correct metric type.

Answer

Summary

Answer

Counter

Answer

Histogram

Question 14

If you are using a Histogram, what is the purpose of the '_sum' metric?

Accepted Answer

To store the sum of observations. The _sum metric provides the sum of all observed values, which allows calculating the average when combined with the _count metric.

Answer

To store the median

Answer

To store the maximum value

Answer

To store the total count

Question 15

What is the recommended approach for metrics that only need to be exposed periodically?

Accepted Answer

Expose consistently. If metrics are not always available, they should still be exposed (perhaps with a null or default value) to ensure consistent scraping.

Answer

Only export when changing

Answer

Use Pushgateway

Answer

Delete the metric