PCA Practice Test 5 — 25 Questions

Question 1

What is the effect of using a 'Summary' metric with client-side quantiles?

Accepted Answer

It prevents cross-instance aggregation. Client-side quantiles are calculated per instance, making it impossible to aggregate them across multiple instances of an application.

Answer

It improves performance

Answer

It allows cross-instance aggregation

Answer

It doubles the scrape time

Question 2

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

Accepted Answer

The Prometheus server. In the Prometheus pull model, the Prometheus server is the component that initiates scrapes by sending HTTP GET requests to the /metrics endpoint exposed by exporters. The exporter's job is to expose metrics, not to scrape them. This is why custom exporters only need to serve metrics in the Prometheus text format — the server handles the scraping schedule.

Answer

The Pushgateway

Answer

The exporter itself

Answer

The client library

Question 3

A Histogram has buckets [0.1, 0.5, 1, 5]. A request takes 0.7 seconds. Which buckets will be incremented?

Accepted Answer

1, 5. Prometheus histogram buckets are cumulative: each bucket counts all observations less than or equal to its upper bound. A 0.7-second request is ≤1 and ≤5, so the buckets with upper bounds 1 and 5 are both incremented. The 0.1 and 0.5 buckets are not incremented because 0.7 exceeds those bounds.

Answer

None

Answer

0.1, 0.5

Answer

Only 1

Question 4

A developer wants to track the total number of requests received by a web service. Which metric type is most appropriate for this requirement?

Accepted Answer

Counter. A Counter is a cumulative metric that only increases (or resets to zero on restart), making it ideal for tracking the total number of requests received by a web service. Prometheus counters are used with rate() or increase() functions to calculate request rates over time.

Answer

Summary

Answer

Histogram

Answer

Gauge

Question 5

Which THREE of the following are considered part of the 'Four Golden Signals' of monitoring?

Accepted Answer

Errors. The four golden signals are Latency, Traffic, Errors, and Saturation.

Answer

Disk Space

Answer

Up-time

Question 6

Which TWO of the following are valid data types returned by PromQL queries? (Choose two)

Accepted Answer

Range vector. PromQL, the query language used by Prometheus, defines exactly four expression data types: instant vector, range vector, scalar, and string. Option B (Range vector) is correct because a range vector is a set of time series containing a range of data points over time for each series, produced by appending a duration selector like [5m] to a selector (e.g., http_requests_total[5m]). Option D (Instant vector) is correct because it is the most common PromQL result type: a set of time series containing a single sample for each series at a given timestamp, returned by expressions such as http_requests_total. The unmarked options do not belong: 'Histogram matrix' (A) is not a PromQL type—histograms are exposed as instant or range vectors of bucket series, and 'matrix' is not a PromQL data type name; 'Log stream' (C) is a Loki concept, not PromQL; and 'Distributed trace' (E) is a tracing data type (e.g., from Tempo/Jaeger), not a PromQL return type.

Answer

Histogram matrix

Answer

Log stream

Answer

Distributed trace

Question 7

What is the difference between 'count' and 'count_values'?

Accepted Answer

count returns the number of series; count_values returns the frequency of values.. count aggregates by number of series, while count_values counts the number of occurrences of each sample value.

Answer

count_values is faster.

Answer

count is for gauges; count_values is for counters.

Answer

There is no difference.

Question 8

Which tool allows you to visualize Prometheus alerts directly in a web UI?

Accepted Answer

Alertmanager UI. Alertmanager ships with a built-in web UI (typically served on port 9093) that displays active alerts, silences, and grouping status, allowing operators to visualize and manage alerts directly. It is the canonical tool for inspecting which alerts are firing, which are silenced, and how they are grouped before notification. The Prometheus server's own UI shows firing alerts via the /alerts endpoint, but the Alertmanager UI is the dedicated interface for alert lifecycle management.

Answer

Node Exporter

Answer

Pushgateway

Answer

Prometheus CLI

Question 9

Which TWO of the following are valid data types in Prometheus?

Accepted Answer

Gauge. In Prometheus, the four core metric types are Counter, Gauge, Histogram, and Summary, so option B (Gauge) is correct because a gauge represents a value that can arbitrarily go up and down, such as temperature or current memory usage, and option C (Counter) is correct because a counter is a cumulative metric that only increases (or resets to zero on restart), such as total HTTP requests. These types are defined in the Prometheus client libraries and exposed via the text exposition format with TYPE annotations like 'counter' and 'gauge'. The other options are not Prometheus metric types: List (A) and Set (D) are not part of the Prometheus data model, and Boolean (E) is not a native metric type either, since boolean-like states are typically represented using a Gauge with values 0 or 1.

Answer

List

Answer

Set

Answer

Boolean

Question 10

When executing a subquery in PromQL, such as 'max_over_time(rate(http_request_total[5m])[30m:1m])', what does the resolution parameter ('1m') specify?

Accepted Answer

The evaluation step size at which the inner expression is run across the subquery window.. The resolution inside subquery brackets specifies the evaluation step size at which the inner expression is evaluated within the subquery range.

Answer

The smoothing factor applied to eliminate high-frequency noise.

Answer

The time-to-live for cached subquery results in Prometheus storage.

Answer

The minimum scrape interval of the target exporter.

Question 11

What is the primary role of the 'Alertmanager'?

Accepted Answer

To manage and route alerts generated by Prometheus.. Alertmanager is responsible for grouping, silencing, and routing alerts to external systems like PagerDuty or email.

Answer

To store long-term metric data.

Answer

To scrape metrics from targets.

Answer

To visualize metrics in dashboards.

Question 12

Which THREE are true regarding the Prometheus TSDB?

Accepted Answer

It uses an inverted index for fast searching.. It uses blocks, WAL, and index files, and it is optimized for time-series data.

Answer

It uses a B-tree for all queries.

Answer

It is a relational database.

Question 13

Which TWO of the following are valid ways to run Prometheus?

Accepted Answer

As a container. Option B is correct because Prometheus is commonly deployed as a container (e.g., the official prom/prometheus Docker image) running its server process in an isolated environment. Option C is correct because Prometheus ships as a standalone compiled Go binary that can be downloaded and executed directly on a host without any container runtime. Option A is wrong because Prometheus is a server-side monitoring system, not a browser extension. Option D is wrong because Prometheus is a standalone time-series database and monitoring server, not a library embedded into a database engine. Option E is wrong because Prometheus runs entirely in user space and is never implemented as a kernel module.

Answer

As a browser extension

Answer

As a database engine library

Answer

As a kernel module

Question 14

Why might you use an 'exporter' in Prometheus?

Accepted Answer

To bridge non-Prometheus metrics to Prometheus format.. An exporter in Prometheus is a component that exposes metrics from a system that does not natively speak the Prometheus exposition format, translating them into Prometheus-compatible metrics on an HTTP endpoint. Prometheus then scrapes that endpoint, allowing monitoring of databases, hardware, message queues, and other third-party systems that lack native /metrics support.

Answer

To increase the scrape interval.

Answer

To secure the Prometheus server.

Answer

To push logs to Prometheus.

Question 15

You are monitoring server hardware metrics using node_exporter. You observe that the metrics are not showing up in Prometheus. Which initial troubleshooting step is most effective?

Accepted Answer

Verify node_exporter is listening on the expected port and accessible.. The node_exporter must be running and listening on the expected port (9100 by default) for the Prometheus server to scrape it. Verifying the port ensures the endpoint is reachable.

Answer

Increase the scrape interval in the Prometheus configuration.

Answer

Disable all collectors in node_exporter to reduce overhead.

Answer

Check if the Prometheus server is running in high availability mode.

Question 16

Which THREE of the following are valid set operators in PromQL for combining instant vectors? (Choose THREE)

Accepted Answer

unless. In PromQL, the set operators available for combining instant vectors are `and`, `or`, and `unless`. Option D (`and`) is correct because it returns the elements of the left-hand vector that also exist in the right-hand vector, matching on labels. Option E (`or`) is correct because it returns all elements of the left-hand vector plus any elements from the right-hand vector that do not have matching label sets on the left. Option C (`unless`) is correct because it returns elements of the left-hand vector that do not have matching label sets in the right-hand vector. Options A (`intersect`) and B (`union`) are not valid PromQL set operators; the intersection behavior is expressed by `and`, and union-like behavior is expressed by `or`, so neither keyword exists in the language.

Answer

intersect

Answer

union

Question 17

Which TWO of the following are true about the node_exporter?

Accepted Answer

It runs on port 9100 by default. Option C is correct because node_exporter's default listen address is :9100, so Prometheus scrapes host metrics from http://<host>:9100/metrics unless overridden with --web.listen-address. Option E is correct because node_exporter's collectors read from /proc and /sys on Linux to expose kernel-level metrics such as node_cpu_seconds_total, node_memory_MemAvailable_bytes, node_load1, and node_disk_io_time_seconds_total. Option A is wrong because node_exporter is a host/OS metrics exporter, not a database exporter; database monitoring uses exporters like mysqld_exporter, postgres_exporter, or oracledb_exporter. Option B is wrong because node_exporter is a passive exporter that only responds when Prometheus scrapes its /metrics endpoint; active probing is done by blackbox_exporter. Option D is wrong because node_exporter is designed for Unix-like systems (Linux, BSD, macOS) and does not support Windows out of the box; Windows host metrics require windows_exporter.

Answer

It is for database monitoring

Answer

It performs active monitoring

Answer

It supports Windows out of the box

Question 18

Which THREE of the following are valid Alertmanager grouping parameters?

Accepted Answer

group_by. In Alertmanager's configuration, the route block supports the grouping parameters group_by, group_wait, and group_interval, which is why options B, C, and D are correct. group_by (B) specifies the labels used to aggregate related alerts into a single notification, such as grouping by 'alertname' or 'cluster'. group_wait (D) sets how long Alertmanager waits to buffer alerts for the same group before sending the initial notification, defaulting to 30s. group_interval (C) defines how long to wait before sending a new notification about a group after the first one, defaulting to 5m. The unmarked options do not belong: alert_timeout (A) is not an Alertmanager parameter (timeouts appear in receivers like webhook or in Prometheus scrape configs), and resolve_delay (E) is not a valid Alertmanager grouping setting either.

Answer

alert_timeout

Answer

resolve_delay

Question 19

What is the behavior of the clamp_max() function when applied to an instant vector?

Accepted Answer

It restricts all values in the vector so that none exceed the specified maximum.. clamp_max(v, max) returns the input vector with every sample value capped at the specified maximum: values above max are replaced by max, while values at or below max pass through unchanged. It does not drop or flag series — it mutates the values in place. This is useful for capping spikes in graphs or enforcing upper bounds in derived metrics.

Answer

It drops any time series whose value exceeds the specified maximum.

Answer

It generates an alert if any time series exceeds the maximum.

Answer

It sets values exceeding the maximum to NaN.

Question 20

What is the default port that Prometheus listens on?

Accepted Answer

9090. 9090 is the well-known default port for the Prometheus server web interface.

Answer

9100

Answer

9093

Answer

8080