PCDE Applying Site Reliability Engineering Practices to a Service Practice Test 4 — 15 Questions

Question 1

An SRE team defines an SLI as the proportion of good requests to valid requests over a 1-minute window. They set an SLO of 99.9% availability over 30 days. Which error budget burn rate alert configuration should they use to detect rapid consumption of the error budget within 1 hour?

Accepted Answer

Alert on burn rate of 14x over a 1-hour window. A fast burn alert uses a short window (1h) and a high burn rate (14x) to detect rapid error budget consumption quickly.

Answer

Alert on burn rate of 2x over a 24-hour window

Answer

Alert on burn rate of 10x over a 30-minute window

Answer

Alert on burn rate of 5x over a 6-hour window

Question 2

A team wants to reduce toil from manual database backups. They estimate the toil takes 10 hours per week. What is the maximum amount of toil they should allow to keep toil under 50% of their time according to SRE best practices?

Accepted Answer

20 hours per week. SRE best practices recommend that toil should not exceed 50% of an SRE team's time. If the team works 40 hours per week, 50% is 20 hours. Currently they spend 10 hours, which is under the cap.

Answer

5 hours per week

Answer

40 hours per week

Answer

10 hours per week

Question 3

During an incident, the incident commander delegates tasks to multiple teams. After the incident is resolved, the team holds a postmortem. Which of the following is a key principle of a blameless postmortem culture?

Accepted Answer

Analyze contributing factors and implement action items with owners. Blameless postmortems focus on identifying system and process failures, not individual mistakes. The goal is to improve reliability.

Answer

Focus on human error and retraining

Answer

Identify the individual responsible and assign corrective action

Answer

Share the postmortem only with the incident commander

Question 4

A service has an SLO of 99.9% availability over a 30-day rolling window. The team wants to use Cloud Monitoring to create a request-based SLO. Which configuration is correct?

Accepted Answer

Use a request-based metric: good request count / valid request count. For a request-based SLO, you define two metrics: good request count and valid request count. The SLO is the ratio of good to valid requests.

Answer

Use an error budget metric: total allowed errors over 30 days

Answer

Use a latency metric: proportion of requests under threshold

Answer

Use a window-based metric: good minutes / total minutes

Question 5

A team notices that a critical microservice often fails when the downstream database is slow. They want to test the service's resilience by injecting latency into the database dependency. Which GCP tool should they use?

Accepted Answer

Traffic Director with HTTP fault filter. Chaos Engineering practices on GCP can be implemented using Traffic Director's fault injection or Chaos Mesh. Traffic Director's HTTP fault filter can inject latency into traffic.

Answer

Cloud Load Balancing logging

Answer

VPC Flow Logs

Answer

Cloud Armor

Question 6

What is the primary purpose of an error budget?

Accepted Answer

To determine how much risk the service can tolerate while maintaining the SLO. An error budget is the amount of acceptable unreliability (e.g., downtime) within an SLO. It allows teams to balance reliability with innovation by permitting some failures.

Answer

To track the number of bugs in production

Answer

To allocate budget for cloud resources

Answer

To measure customer satisfaction

Question 7

An SRE team wants to automate a repetitive manual task that involves moving files from Cloud Storage to BigQuery and then deleting the source files. Which GCP service is BEST suited for this toil reduction?

Accepted Answer

Cloud Functions. Cloud Functions is ideal for event-driven automation. It can trigger on Cloud Storage events, process data, and delete files.

Answer

Cloud Build

Answer

Cloud Scheduler

Answer

Compute Engine

Question 8

A service has an SLO of 99.99% availability over 28 days. The team wants to set up a slow burn alert that will notify them within 6 hours if error budget consumption is at 5x the budgeted rate. How much error budget has been consumed after 6 hours at this rate? The total error budget for 28 days is 4 minutes and 2 seconds (242 seconds).

Accepted Answer

10.8 seconds. The total error budget is 242 seconds over 28 days (672 hours). The budgeted error rate is 242 seconds / 672 hours ≈ 0.3601 seconds per hour. At a 5x burn rate, the consumption rate is 5 × 0.3601 ≈ 1.8005 seconds per hour. Over 6 hours, consumption = 1.8005 × 6 ≈ 10.8 seconds. Therefore, 10.8 seconds of error budget have been consumed, which corresponds to option A.

Answer

7.2 seconds

Answer

2.4 seconds

Answer

4.8 seconds

Question 9

Which of the following is an example of toil according to SRE principles?

Accepted Answer

Manually restarting failed pods in a Kubernetes cluster. Toil is manual, repetitive, automatable work with no enduring value. Manually restarting failed pods is a classic example.

Answer

Reviewing code from a junior developer

Answer

Writing a new feature for the application

Answer

Designing a new microservice architecture

Question 10

During an incident, the incident commander notices that multiple teams are working on the same issue without coordination. Which structure should be implemented to improve incident response?

Accepted Answer

Assign a single incident commander to coordinate all teams. An incident command system (ICS) establishes a clear hierarchy with an incident commander who coordinates teams, assigns roles (e.g., operations lead, communications lead), and ensures focused response.

Answer

Use a chatbot to broadcast updates without a commander

Answer

Have each team work independently and report after resolution

Answer

Escalate to the VP of Engineering to make decisions

Question 11

A team wants to implement Chaos Engineering on GKE to test the resilience of their microservices by randomly killing pods and injecting network latency. Which tool is specifically designed for this purpose on GKE?

Accepted Answer

Chaos Mesh. Chaos Mesh is an open-source chaos engineering platform for Kubernetes. It provides fault injection (pod kill, network latency, etc.) and integrates with GKE.

Answer

Cloud Armor

Answer

Cloud Shell

Answer

Traffic Director

Question 12

A team has a service with an SLO of 99.5% uptime over 30 days. They track error budget and want to alert when the error budget is almost exhausted. What is their total error budget in minutes per month?

Accepted Answer

216 minutes. Error budget = 100% - SLO = 0.5%. Over 30 days (720 hours), 0.5% of 720 hours = 3.6 hours = 216 minutes.

Answer

360 minutes

Answer

43.2 minutes

Answer

72 minutes

Question 13

An SRE team is defining SLIs for a data pipeline that ingests events from a pub/sub topic and writes to BigQuery. Which two metrics are good SLIs for pipeline freshness? (Choose TWO.)

Accepted Answer

Age of the oldest unprocessed message in the subscription. Pipeline freshness measures how up-to-date the data is. Latency of most recent event from ingestion to table and age of oldest unprocessed message are direct measures.

Answer

CPU utilization of Dataflow workers

Answer

Number of events published per second

Answer

Total number of rows in BigQuery

Question 14

A team wants to implement an on-call rotation using Cloud Monitoring and third-party tools. Which three components are essential for setting up on-call alerting? (Choose THREE.)

Accepted Answer

An escalation policy. Essential components: alerting policy to trigger notifications, notification channel to reach on-call engineers, and escalation policy to handle unacknowledged alerts. A dashboard and runbook are helpful but not essential for the on-call rotation itself.

Answer

A Cloud Monitoring dashboard

Answer

A runbook for incident response

Question 15

Which two practices are characteristic of a blameless postmortem? (Choose TWO.)

Accepted Answer

Creating action items with owners and deadlines. Blameless postmortems focus on systemic causes and create action items to prevent recurrence. They avoid blaming individuals.

Answer

Assigning punitive measures to prevent recurrence

Answer

Identifying the employee who made the error

Answer

Keeping the postmortem confidential within the incident response team