PCA Practice Test 4 — 25 Questions

Question 1

When instrumenting an application, why is it recommended to use a fixed set of label names?

Accepted Answer

To avoid cardinality explosion. Dynamically changing label names creates new time series, which can lead to cardinality explosion and storage issues.

Answer

To increase resolution

Answer

For better formatting

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To simplify coding

Question 2

You are troubleshooting high cardinality in your metrics. What is a common cause for this in a custom exporter?

Accepted Answer

Including dynamic values like IDs or timestamps in label values.. High cardinality occurs when a label value has an unbounded number of unique values (like a request ID or a timestamp), causing a massive explosion in the number of unique time series.

Answer

Using too many different metrics.

Answer

Scraping the exporter too frequently.

Answer

Using the wrong metric type for a simple count.

Question 3

When using the 'repeat_interval' in Alertmanager, what does it define?

Accepted Answer

How often to resend firing alerts. The repeat_interval defines how long to wait before re-sending a notification for an alert that is still active.

Answer

The timeout for the receiver

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The TTL of the alert

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How long to wait before firing

Question 4

If you have a scrape_interval of 15s, what is the recommended minimum scrape_timeout?

Accepted Answer

10s. The timeout should generally be slightly less than or equal to the scrape_interval, but it must be sufficient to allow the target to respond.

Answer

5s

Answer

30s

Answer

15s

Question 5

When implementing a custom exporter, what format must the output follow to be correctly scraped by Prometheus?

Accepted Answer

Prometheus Text Format. Prometheus requires a text-based format where each metric is represented by lines, including name, labels, and values.

Answer

JSON

Answer

XML

Answer

Binary Protobuf

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

Which TWO factors directly influence the accuracy of quantile calculations when using Prometheus Summary metrics?

Accepted Answer

The configured quantiles (e.g., 0.9, 0.99).. Summaries compute quantiles on the client side, and accuracy is determined by the configured quantiles and the sliding time window over which they are calculated.

Answer

The total number of instances scraping the metric.

Answer

The CPU architecture of the client host.

Answer

The number of buckets defined in the configuration.

Question 8

An SRE team is transitioning from traditional logs to metrics for performance monitoring. Which scenario best justifies using metrics over logs?

Accepted Answer

Tracking the request rate per second on a web server.. Metrics are numerical representations of data measured over time, making them efficient for time-series analysis and alerting, whereas logs are better for debugging specific events.

Answer

Auditing user access attempts for compliance.

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Storing the payload of a failed transaction for later inspection.

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Recording the stack trace of a Java application crash.

Question 9

Which component is responsible for executing queries written in PromQL?

Accepted Answer

Prometheus Server. The Prometheus server itself contains the query engine that processes PromQL expressions.

Answer

Exporter

Answer

Alertmanager

Answer

Grafana

Question 10

Why are 'logs' essential for debugging, even with perfect metrics?

Accepted Answer

Logs contain detailed context about specific events.. Logs provide the granular, detailed context (like specific error messages or stack traces) that metrics cannot provide.

Answer

Metrics are too slow.

Answer

Logs are free to store.

Answer

Metrics cannot be used for debugging.

Question 11

How do you apply a global notification delay in Alertmanager?

Accepted Answer

By using the group_wait field. The 'group_wait' parameter at the root route level defines the time to wait before sending an initial notification for a new alert group.

Answer

By setting the repeat_interval

Answer

By creating a silence for the first 5 minutes

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By modifying the Prometheus rule interval

Question 12

You have a recording rule that fails to evaluate because of a 'labels conflict'. What is the most likely cause?

Accepted Answer

The aggregation results in duplicate label sets. A label conflict occurs when the recording rule tries to create a metric with labels that are already present or restricted, or when the aggregation produces duplicate label sets.

Answer

The rule file has invalid YAML indentation

Answer

The evaluation interval is too low

Answer

The metric name is already in use

Question 13

You are creating a recording rule to calculate the rate of requests over 5 minutes. Why would you prefer a recording rule over a direct dashboard query?

Accepted Answer

To reduce query latency on dashboards. Recording rules precompute expensive queries, reducing the load on Prometheus and speeding up dashboard loading times.

Answer

To bypass the retention settings of Prometheus

Answer

To increase the resolution of the data

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To automatically send alerts to PagerDuty

Question 14

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 15

Which TWO of the following are common reasons to use the Pushgateway?

Accepted Answer

For batch jobs that run for seconds. Pushgateway is used for batch jobs that finish quickly and for processes that are behind a firewall.

Answer

To monitor long-running servers

Answer

To act as a reverse proxy

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When metrics need to be stored in SQL

Question 16

You need to monitor the duration of database queries. Which metric type is best for calculating quantiles on the server side?

Accepted Answer

Histogram. Summaries calculate configurable quantiles on the client side, while Histograms require server-side calculations.

Answer

Gauge

Answer

Counter

Answer

Summary

Question 17

You have two alerts: 'InstanceDown' and 'HighErrorRate'. You want to inhibit 'HighErrorRate' if 'InstanceDown' is firing for the same instance. Where do you configure this logic?

Accepted Answer

In the Alertmanager 'inhibit_rules' configuration. Inhibition rules are defined within the 'inhibit_rules' section of the Alertmanager configuration file.

Answer

In the Prometheus recording rules file

Answer

In the Grafana Alerting panel

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In the Prometheus 'alerting' rule block

Question 18

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

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Logarithmic exponent

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Last entry

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

You are monitoring a legacy batch processing job that runs for only 30 seconds once every 24 hours. Which Prometheus component is necessary to collect these metrics?

Accepted Answer

Prometheus Pushgateway. Since the job is short-lived, Prometheus's standard scrape interval will likely miss it. The Pushgateway allows the job to push metrics before exiting.

Answer

Prometheus Exporter

Answer

Prometheus Federation

Answer

Prometheus Alertmanager