PCA Observability Concepts Practice Test 1 — 15 Questions

Question 1

Which component is strictly required to monitor batch jobs in a Prometheus ecosystem?

Accepted Answer

Pushgateway. The Pushgateway is specifically designed to allow ephemeral batch jobs to push metrics, which Prometheus then pulls.

Answer

Grafana

Answer

Alertmanager

Answer

PromQL

Question 2

You are deploying Prometheus in a cluster with highly dynamic ephemeral pods. Which concern is the most significant regarding cardinality?

Accepted Answer

The memory overhead of storing time series with unique label sets.. High cardinality arises from labels with high-variance values, which can lead to memory exhaustion in the Prometheus TSDB.

Answer

The network bandwidth used by the pushgateway.

Answer

The disk space used by WAL logs.

Answer

The number of targets being scraped.

Question 3

You notice that your Prometheus instance memory usage is growing linearly despite constant traffic. What is the most likely cause?

Accepted Answer

Increasing metric cardinality.. If cardinality (unique label combinations) increases over time, the number of active time series keeps growing, increasing RAM usage.

Answer

CPU throttling.

Answer

Network latency.

Answer

Too many alert rules.

Question 4

In the context of the Four Golden Signals, what does 'Saturation' measure?

Accepted Answer

The amount of queued work.. Saturation measures how 'full' a service is, typically defined by identifying the most constrained resource (e.g., CPU, RAM, or disk IO).

Answer

The number of 5xx errors.

Answer

The speed of the network.

Answer

The number of successful requests.

Question 5

A legacy batch job runs once per day and finishes in seconds. Why is a standard Prometheus pull model inadequate here?

Accepted Answer

The job is too fast for HTTP polling.. Prometheus pull intervals are typically set to seconds or minutes; a job that finishes quickly might never be 'up' when Prometheus scrapes it.

Answer

The data is too large for memory.

Answer

Pull model is insecure.

Answer

Prometheus cannot scrape batch jobs.

Question 6

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 measures the time it takes to service a request, which directly indicates performance issues in dependencies.

Answer

Errors

Answer

Saturation

Answer

Traffic

Question 7

What is the primary drawback of using the Pushgateway for long-running services?

Accepted Answer

It bypasses Prometheus's liveness check for the source.. Using the Pushgateway removes the 'up' status check that Prometheus performs on targets, and it can become a bottleneck or single point of failure.

Answer

It requires manual restarts.

Answer

It lacks metric persistence.

Answer

Prometheus cannot query the Pushgateway.

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.

Answer

Storing the payload of a failed transaction for later inspection.

Answer

Recording the stack trace of a Java application crash.

Question 9

What is the primary difference between a metric and a log?

Accepted Answer

Metrics represent snapshots of state; logs represent discrete events.. Metrics are aggregated, numeric data points over time, while logs are timestamped records of specific events.

Answer

Metrics are for debugging; logs are for alerting.

Answer

Logs are cheaper to store.

Answer

Logs are always real-time.

Question 10

Which golden signal would you monitor to detect if a specific API endpoint is returning 404s?

Accepted Answer

Errors. The 'Errors' signal tracks the rate of failed requests, including HTTP 4xx and 5xx codes.

Answer

Traffic

Answer

Saturation

Answer

Latency

Question 11

When configuring Service Discovery in Kubernetes, why might you use relabeling?

Accepted Answer

To reduce cardinality by dropping high-variance labels.. Relabeling is used to modify, drop, or keep metrics based on label values, which is essential for managing cardinality and filtering unwanted data.

Answer

To encrypt metric traffic.

Answer

To increase scrape frequency.

Answer

To store logs in Prometheus.

Question 12

Why are traces considered distinct from metrics in observability?

Accepted Answer

Traces track individual request lifecycles through services.. Traces provide context on a single request's path through a distributed system, whereas metrics provide aggregated health status.

Answer

Traces are always numeric.

Answer

Traces are only for frontend applications.

Answer

Metrics replace traces.

Question 13

Which monitoring philosophy is core to the Prometheus architecture?

Accepted Answer

Centralized pull-based scraping.. Prometheus favors the pull model, where the server controls the scrape rate and frequency, providing better control over the load on the monitoring system.

Answer

Agent-less log aggregation.

Answer

Push-based data ingestion.

Answer

Event-driven architecture.

Question 14

What is the primary benefit of using a pull-based model for monitoring?

Accepted Answer

The Prometheus server can detect target failure.. The pull model allows the monitoring server to detect when a target is down and prevents the target from overwhelming the monitoring system.

Answer

It supports higher data throughput.

Answer

It is easier to configure for firewalls.

Answer

It avoids network security issues.

Question 15

You are seeing 'Too many active series' in your Prometheus logs. Which action should be your first priority to address this?

Accepted Answer

Analyze the number of active series per label name.. Identifying which labels are causing the high cardinality is the standard first step to prevent OOM (Out Of Memory) crashes.

Answer

Switch to a different monitoring tool.

Answer

Disable all alerting rules.

Answer

Increase Prometheus memory limits.