PCA Observability Concepts Practice Test 2 — 15 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 high-cardinality dimension like 'user_id' can explode the number of time series created, crashing the TSDB.

Answer

The query speed will increase.

Answer

Prometheus will reject the metric.

Answer

The metric will stop recording.

Question 2

Which of these is considered a 'counter' in Prometheus?

Accepted Answer

Total number of HTTP requests processed.. A counter is a cumulative metric that only ever goes up, used for things like request totals.

Answer

Temperature of a server room.

Answer

Average latency over 5 minutes.

Answer

Current memory usage of a process.

Question 3

What is the purpose of a Gauge metric?

Accepted Answer

To track values that fluctuate up and down.. A gauge represents a single numerical value that can arbitrarily go up and down, such as temperature or memory usage.

Answer

To track request rates.

Answer

To track job start times.

Answer

To track request durations.

Question 4

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 5

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 6

Why might you use an 'exporter' in Prometheus?

Accepted Answer

To bridge non-Prometheus metrics to Prometheus format.. Exporters are used to convert metrics from systems that don't natively expose Prometheus format into something Prometheus can scrape.

Answer

To increase the scrape interval.

Answer

To secure the Prometheus server.

Answer

To push logs to Prometheus.

Question 7

Which metric type would best capture the distribution of request latencies?

Accepted Answer

Histogram. A Histogram samples observations (usually request durations) and counts them in configurable buckets, allowing for percentiles.

Answer

Summary

Answer

Gauge

Answer

Counter

Question 8

Why does the 'rate()' function in PromQL behave unexpectedly on counter resets?

Accepted Answer

It detects the reset and ignores the wrap-around.. A counter reset (going to 0) would produce a massive negative number if not handled. 'rate()' automatically accounts for this by assuming a reset occurred.

Answer

It returns an error.

Answer

It requires a manual offset.

Answer

It stops recording the metric.

Question 9

What is the purpose of 'labels' in Prometheus?

Accepted Answer

To identify unique time series.. Labels provide metadata to metrics, allowing for multi-dimensional querying and filtering (e.g., job='web', instance='1.2.3.4').

Answer

To store the actual data values.

Answer

To define the scrape interval.

Answer

To set the alert threshold.

Question 10

A dashboard shows a latency spike that doesn't correlate with CPU usage. What should you investigate next?

Accepted Answer

Disk I/O and network saturation.. If CPU is not the bottleneck, the issue is likely I/O saturation, network contention, or a downstream dependency delay.

Answer

Increase the number of replicas.

Answer

Check the memory limit.

Answer

Delete old metrics.

Question 11

What is 'Monitoring Philosophy' regarding alerts?

Accepted Answer

Alert on symptoms, not causes.. Effective alerting should be actionable, low-noise, and focus on symptoms (what the user sees) rather than causes.

Answer

Alert on every CPU spike.

Answer

Only alert during business hours.

Answer

Alert on every error log.

Question 12

Which tool would you pair with Prometheus to visualize the collected data?

Accepted Answer

Grafana. Grafana is the standard visualization tool that integrates deeply with Prometheus as a data source.

Answer

Kibana

Answer

PromQL

Answer

Alertmanager

Question 13

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 14

Which of the following describes the 'pull' model's benefit regarding service discovery?

Accepted Answer

Targets don't need to know where Prometheus is.. Prometheus can dynamically discover targets (via Kubernetes API, Consul, etc.) and automatically start scraping, removing the need to register every new pod.

Answer

Prometheus is always the first to start.

Answer

Targets push data when they are ready.

Answer

It reduces network traffic.

Question 15

You need to measure the P99 latency of your service. Which PromQL function do you use on a Histogram?

Accepted Answer

histogram_quantile(). The 'histogram_quantile' function is required to calculate quantiles from bucketed histogram data.

Answer

avg()

Answer

sum()

Answer

rate()