PCA Practice Test 3 — 30 Questions

Question 1

A team wants to visualize metrics from Prometheus in Grafana. What is the standard way to connect these two services?

Accepted Answer

Add a 'Prometheus' data source in Grafana. Grafana allows users to add Prometheus as a 'Data Source' by providing the URL of the Prometheus server.

Answer

Upload a JSON file to Prometheus

Answer

Configure a Prometheus scrape job for Grafana

Answer

Install the 'Grafana-exporter' in Prometheus

Question 2

Your application has a short-lived batch job that finishes before the Prometheus server can scrape it. What architectural component should be used?

Accepted Answer

Pushgateway. The Pushgateway is designed to allow ephemeral and batch jobs to expose their metrics to Prometheus.

Answer

Prometheus API

Answer

Alertmanager

Answer

node_exporter

Question 3

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 4

You have a histogram metric tracking request durations. You need to calculate the 99th percentile across all instances in a cluster. Why is this difficult with standard Prometheus metrics?

Accepted Answer

Aggregating histograms requires complex math because they track bucket counts, not raw values.. Histograms track counts in predefined buckets. Without knowing the exact distribution of values within those buckets, calculating accurate quantiles across multiple instances or time windows is an approximation.

Answer

Histograms can only be used on a single instance.

Answer

The Prometheus server does not support mathematical operations.

Answer

Histograms are not designed to be aggregated across multiple labels.

Question 5

You need to ensure that an alert remains 'firing' for 5 minutes before the Alertmanager is notified. Which field in the Prometheus alerting rule should you configure?

Accepted Answer

for. The 'for' field in a Prometheus alerting rule specifies the duration for which a condition must be true before the alert transitions from 'pending' to 'firing'.

Answer

pending_duration

Answer

delay

Answer

hold_time

Question 6

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 7

What is the default port used by node_exporter?

Accepted Answer

9100. The standard Prometheus convention for node_exporter is port 9100.

Answer

9115

Answer

9090

Answer

8080

Question 8

You are performing a 'label_replace' operation. What is the correct syntax for a regex capture group?

Accepted Answer

$1. Prometheus uses standard RE2 regex syntax, where capture groups are accessed via $1, $2, etc.

Answer

\1

Answer

{1}

Answer

%1

Question 9

What is the primary function of the 'scrape_timeout' configuration?

Accepted Answer

It limits the duration of the HTTP connection.. It defines how long Prometheus waits for a response from the target before considering the scrape a failure.

Answer

It determines how long to keep metrics in memory.

Answer

It sets the interval between scrapes.

Answer

It restricts the size of the metric payload.

Question 10

Your team is defining Service Level Objectives (SLOs) for a web application. Which metric is most indicative of the 'Traffic' golden signal?

Accepted Answer

Number of requests per second. Traffic is a measure of demand on the system, typically represented by request rate per second.

Answer

Database connection pool size

Answer

Total disk I/O wait

Answer

Number of active error logs

Answer

Average CPU utilization percentage

Question 11

In the Prometheus data model, what is a 'sample'?

Accepted Answer

A value and a timestamp. A sample is a value-timestamp pair associated with a specific series.

Answer

The metric name

Answer

A label key-value pair

Answer

An alert rule

Question 12

Which mechanism allows Prometheus to discover targets by reading a list from a file?

Accepted Answer

file_sd_configs. file_sd_configs is designed to read target lists from JSON or YAML files.

Answer

dns_sd_configs

Answer

static_configs

Answer

consul_sd_configs

Question 13

A batch job runs for only 30 seconds every hour. How should you expose these metrics to Prometheus?

Accepted Answer

Use the Pushgateway. The Pushgateway is designed specifically for short-lived jobs that cannot be scraped directly.

Answer

Use an exporter sidecar

Answer

Increase scrape interval to 1 hour

Answer

Add a scrape_config for the batch job

Question 14

When using the 'scrape_timeout', what happens if the timeout is reached?

Accepted Answer

The scrape is marked as failed. If the timeout is reached, the scrape is aborted, and a 'up{job=...} == 0' metric is recorded.

Answer

It automatically retries once

Answer

The previous value is kept indefinitely

Answer

The scrape continues silently

Question 15

Which PromQL aggregator should be used to count the total number of active time series matching a selector?

Accepted Answer

count(up). The count operator counts the number of time series in an instant vector.

Answer

sum(up)

Answer

len(up)

Answer

total(up)

Question 16

What is the default value for the scrape interval?

Accepted Answer

1m. The default scrape interval in Prometheus is 1 minute.

Answer

10s

Answer

30s

Answer

5m

Question 17

What is the primary language used to query Prometheus data?

Accepted Answer

PromQL. PromQL (Prometheus Query Language) is the functional query language for Prometheus.

Answer

Regex

Answer

GraphQL

Answer

SQL

Question 18

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 19

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 20

You need to perform a binary operation between two vectors where the left vector has labels {job="api", instance="a"} and the right vector has labels {job="api"}. You want to match them using the job label while retaining the instance label from the left side. Which modifier configuration is correct?

Accepted Answer

vector_a * on(job) group_left(instance) vector_b. To match on a subset of labels while retaining extra labels on the left side during a one-to-many or many-to-one operation, group_left must be used with the on modifier.

Answer

vector_a * on(instance) group_left(job) vector_b

Answer

vector_a * on(job) group_right(instance) vector_b

Answer

vector_a * ignoring(instance) group_left vector_b