PCA Practice Test 3 — 25 Questions

Question 1

A system is experiencing high latency. You need to identify if the latency is caused by external dependencies. Which of the Four Golden Signals is most relevant for this discovery?

Accepted Answer

Latency. Latency, one of the Four Golden Signals, measures the time it takes to service a request, and it is the signal explicitly designed to reveal slow responses. By breaking latency down by dependency (e.g., downstream API, database, third-party service), you can determine whether external dependencies are the source of the slowdown. This makes Latency the most relevant signal for diagnosing high-latency issues.

Answer

Errors

Answer

Saturation

Answer

Traffic

Question 2

When writing a custom exporter in Python, what is the most common way to expose the metrics?

Accepted Answer

Using start_http_server(). The prometheus_client library provides a start_http_server() method to expose metrics on a specified port.

Answer

Writing to a file

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Using a message queue

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Using a database connection

Question 3

Which TWO are common types of Prometheus exporters?

Accepted Answer

Node Exporter. Node Exporter (A) is a canonical Prometheus exporter that runs on a host and exposes hardware and OS metrics such as CPU, memory, disk, filesystem, and network statistics on /metrics for Prometheus to scrape. Blackbox Exporter (D) is also a standard Prometheus exporter, but it probes external endpoints over HTTP, HTTPS, DNS, TCP, and ICMP and converts the results into Prometheus metrics, making it ideal for availability and latency monitoring. The other options are not established Prometheus exporter types: there is no standard "Log Exporter" (B) since logs are handled by Loki/Promtail rather than Prometheus, "Push Exporter" (C) is not a real exporter type because Prometheus uses the Pushgateway for push-based metrics rather than a push exporter, and "Trace Exporter" (E) relates to distributed tracing systems like OpenTelemetry/Jaeger, not Prometheus metrics collection.

Answer

Log Exporter

Answer

Push Exporter

Answer

Trace Exporter

Question 4

Which Grafana panel type is best for showing a trend of a metric over time?

Accepted Answer

Time series. The Time series panel is the standard for plotting metrics over time.

Answer

Table

Answer

Stat

Answer

Bar gauge

Question 5

An application is emitting logs that contain '5xx' status codes when a service is unavailable. If you want to create an alert that triggers based on the rate of these errors, what is the best practice for observability?

Accepted Answer

Expose a metric incrementing on every 5xx error and alert on the rate of that metric.. Logs are useful for root cause analysis, but for alerting on rates, you should convert the error occurrence into a metric increment, as metrics are more efficient for long-term calculation and alerting.

Answer

Alert directly on the log stream using a log aggregator.

Answer

Use Prometheus to scrape the log file directly.

Answer

Increase log verbosity to trace the request until the error is resolved.

Question 6

You are using the blackbox_exporter to monitor an HTTP endpoint. Which module configuration is required to check the HTTP status code?

Accepted Answer

http_2xx. The http_2xx module is the standard configuration for checking that an endpoint returns a successful HTTP status code.

Answer

dns_query

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tcp_connect

Answer

icmp_ping

Question 7

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

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To store the maximum value

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To store the total count

Question 8

What happens if a label set for a metric changes during its lifetime?

Accepted Answer

A new time series is created. Changing a label set creates a brand new time series in Prometheus.

Answer

An error is logged

Answer

The series is updated in-place

Answer

The metric is deleted

Question 9

What is the purpose of the 'rule_files' configuration?

Accepted Answer

To define alerting and recording rules. rule_files point to recording and alerting rules that Prometheus evaluates.

Answer

To manage user authentication

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To define static targets

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To configure global retention

Question 10

Which annotation is commonly used to provide a human-readable description in an alert?

Accepted Answer

description. The 'summary' or 'description' annotations are standard practices for providing context in alert notifications.

Answer

severity

Answer

instance

Answer

job

Question 11

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 12

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 13

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

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Log aggregation

Answer

Hardware monitoring

Question 14

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 15

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

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delay

Answer

hold_time

Question 16

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 17

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 18

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 19

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.

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It restricts the size of the metric payload.

Question 20

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