PCA Practice Test 4 — 10 Questions

Question 1

A developer adds a 'user_id' label to an HTTP request counter. What is the operational risk?

Accepted Answer

High cardinality will consume excessive memory.. Adding a 'user_id' label to an HTTP request counter creates a label with unbounded, per-user values. Each unique combination of label values produces a distinct time series in Prometheus, so a user_id label can generate thousands or millions of series. Prometheus holds all active series in memory (head block), so this high cardinality rapidly consumes RAM and can destabilize or crash the server.

Answer

The query speed will increase.

Answer

Prometheus will reject the metric.

Answer

The metric will stop recording.

Question 2

Which THREE of these are recommended practices for an observability strategy?

Accepted Answer

Maintain logs for granular incident analysis.. Option A is correct because logs provide the high-cardinality, event-level detail needed for granular incident analysis and root-cause investigation, complementing the aggregate view from metrics and traces. Option B is correct because alerting on symptoms (user-visible impact such as latency or error rate) rather than internal causes reduces noise and false pages, since causes can vary while the symptom reliably indicates user pain. Option E is correct because the Four Golden Signals — latency, traffic, errors, and saturation — are a widely recommended Google SRE framework for monitoring request-driven systems and catching the most important failure modes. Option C is not recommended because a zero threshold would fire alerts constantly on any nonzero value, producing alert fatigue rather than meaningful signal. Option D is not recommended because metrics are cheap and aggregatable but lose per-event context; logs and traces are still required for detailed debugging, so 'metrics for everything' is an overreach.

Answer

Always set alert thresholds to zero.

Answer

Use metrics for everything.

Question 3

Why would you choose to create a recording rule for a complex PromQL query?

Accepted Answer

To reduce dashboard query latency. Recording rules pre-calculate complex queries, making dashboards load faster by querying the pre-computed series instead of re-calculating the entire expression.

Answer

To increase metric resolution

Answer

To bypass authentication

Answer

To enable cross-server alerting

Question 4

Which TWO of the following can be configured globally?

Accepted Answer

scrape_interval. Options C (scrape_interval) and D (evaluation_interval) are correct because both are global configuration parameters in the Prometheus configuration file's top-level `global:` block, where scrape_interval sets the default interval between scraping targets and evaluation_interval sets how often alerting and recording rules are evaluated. These values apply to all scrape jobs and rule groups unless overridden at the job or group level, making them genuinely global settings. The other options do not belong: alertmanager_host is not a valid Prometheus global setting (Alertmanager targets are configured under `alerting: alertmanagers:` with host/port details), storage_path is a command-line flag (`--storage.tsdb.path`) rather than a global config option, and target_labels is not a global configuration directive (labels are applied per scrape job or via relabeling).

Answer

alertmanager_host

Answer

storage_path

Answer

target_labels

Question 5

When evaluating a PromQL query involving arithmetic operators, such as 'vector1 + vector2 * vector3', which operator has the highest precedence?

Accepted Answer

* (Multiplication). In PromQL, arithmetic operators follow standard mathematical precedence: multiplication (*), division (/), and modulo (%) bind tighter than addition (+) and subtraction (-). Therefore in 'vector1 + vector2 * vector3', the multiplication of vector2 and vector3 is evaluated first, and the result is then added to vector1. This mirrors conventional arithmetic rules rather than left-to-right evaluation.

Answer

Both have equal precedence and are evaluated left-to-right.

Answer

+ (Addition)

Answer

Precedence is determined by the order of labels.

Question 6

When using 'irate', what is the impact of choosing a range vector that is too small (e.g., [10s])?

Accepted Answer

It captures high-frequency spikes but can be volatile.. Using a very small range vector with irate, such as [10s], means irate calculates the per-second rate based on only the last two data points within that short window. This can capture rapid changes but makes the result highly sensitive to scrape timing and outliers, leading to volatile output.

Answer

It returns an error if no data points are found.

Answer

The result becomes a scalar.

Answer

The value is capped at 1.

Question 7

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 8

When designing a monitoring strategy, why should you avoid monitoring 'everything'?

Accepted Answer

It leads to signal noise and high resource costs.. Excessive metric collection leads to high storage costs, increased query latency, and signal-to-noise ratio degradation (alert fatigue).

Answer

Logs are always better for everything.

Answer

The network will be saturated.

Answer

Prometheus cannot handle many metrics.

Question 9

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

Answer

To automatically send alerts to PagerDuty

Question 10

When configuring Alertmanager to send notifications to Slack, which block defines the routing tree?

Accepted Answer

route. In Alertmanager's configuration, the route block defines the routing tree that determines how alerts are grouped and which receiver they are sent to. It is the top-level entry point (with child routes for matching) that evaluates alert labels against matchers and dispatches notifications accordingly.

Answer

receivers

Answer

inhibit_rules

Answer

global