PCDE Applying Site Reliability Engineering Practices to a Service Practice Test 7 — 15 Questions

Question 1

A site reliability engineer defines a service's availability SLI as the percentage of successful requests. Which of the following is the correct formula for this SLI?

Accepted Answer

good-request-count / valid-request-count * 100. Availability SLI is typically defined as the count of successful requests divided by total valid requests, measured over a rolling window.

Answer

good-request-count / total-requests (including invalid) * 100

Answer

error-request-count / valid-request-count * 100

Answer

valid-request-count / error-request-count * 100

Question 2

A team has an SLO of 99.9% availability over a 30-day period. How many minutes of downtime does the error budget allow per month?

Accepted Answer

43 minutes. Error budget = 100% - SLO target = 0.1% of total time. 30 days = 43,200 minutes. 0.1% of 43,200 = 43.2 minutes. Rounding gives 43 minutes.

Answer

4.32 minutes

Answer

432 minutes

Answer

4,320 minutes

Question 3

An SRE team implements error budget alerting using Cloud Monitoring. They want to set a 'fast burn' alert that triggers when the error budget burn rate exceeds 14x over a 1-hour window. What is the purpose of this alert?

Accepted Answer

To alert immediately when error budget is being consumed at a rate that would exhaust the budget in approximately 51 hours (14x faster than allowed). Fast burn alerts (e.g., 14x burn rate over 1h) are designed to detect severe, rapid consumption of error budget, prompting immediate investigation. They complement slow burn alerts (5x over 6h) which catch gradual budget erosion.

Answer

To detect gradual, long-term trends in error budget consumption

Answer

To alert when the error budget is completely exhausted

Answer

To trigger a page for on-call engineers when the service is likely to exceed SLO within the next 6 hours

Question 4

A DevOps team wants to reduce toil by automating manual, repetitive tasks that have no enduring value and scale with service growth. Which two characteristics define toil according to SRE principles?

Accepted Answer

It is repetitive and scales with service growth. According to Google's SRE principles, toil is manual, repetitive, automatable, tactical (no enduring value), and scales with service growth. The question asks for two, so the correct answer pairs two of these.

Answer

It is strategic and non-repetitive

Answer

It is automated and provides enduring value

Answer

It is manual and has enduring value

Question 5

An organization wants to implement a blameless postmortem culture after incidents. Which of the following is a key practice in blameless postmortems?

Accepted Answer

Identifying contributing factors using techniques like the 5 Whys. Blameless postmortems focus on identifying contributing factors and systemic issues, not individual blame. The 5 Whys technique helps uncover root causes.

Answer

Firing the responsible engineer to prevent recurrence

Answer

Assigning blame to the engineer who made the mistake

Answer

Immediately implementing a fix without documentation

Question 6

During an incident, an SRE team uses an incident command system. Which role is responsible for coordinating communication and resources, but not for technical debugging?

Accepted Answer

Incident Commander. In incident command, the Incident Commander (IC) focuses on coordination, communication, and resource management, leaving technical debugging to the Operations Lead or other technical roles.

Answer

Subject Matter Expert

Answer

Operations Lead

Answer

Scribe

Question 7

A company uses Cloud Monitoring to create an SLO for a service. They want to define a request-based SLO with a ratio of good requests to valid requests. Which of the following is a valid way to define the SLI in Cloud Monitoring SLOs?

Accepted Answer

Select a metric for good requests and a separate metric for total valid requests, then define the SLI as good-request-count / valid-request-count. Cloud Monitoring SLOs require two metrics: one for good events and one for total valid events. The ratio is good/total. The correct configuration uses separate metrics for good and valid requests.

Answer

Use a distribution metric for latency and set a threshold for good latency

Answer

Create a custom metric for requests and use Cloud Monitoring's built-in availability SLI for HTTP services

Answer

Use a single metric that indicates success (1 for success, 0 for failure) and set a threshold filter

Question 8

A team wants to inject latency faults into their microservices running on Google Kubernetes Engine (GKE) to test resilience. Which tool or service should they use?

Accepted Answer

Chaos Mesh. Chaos Mesh is a popular open-source chaos engineering platform for Kubernetes, capable of injecting faults like latency, pod failures, and network partitions. It integrates well with GKE.

Answer

Cloud Build to orchestrate failure scenarios

Answer

Traffic Director fault injection with HTTP fault filter

Answer

Cloud Functions to simulate latency by delaying responses

Question 9

An SRE team wants to track the amount of toil their team performs each week. According to SRE best practices, what is the recommended maximum percentage of time that should be spent on toil?

Accepted Answer

50%. Google SRE recommends that teams spend no more than 50% of their time on toil, leaving the rest for engineering work that reduces future toil or improves the service.

Answer

25%

Answer

10%

Answer

75%

Question 10

An SRE team uses PagerDuty for on-call rotation. They receive a critical alert at 2 AM. According to incident management best practices, what should the on-call engineer do first?

Accepted Answer

Acknowledge the alert and begin triage according to the runbook. The first step is to acknowledge the alert to signal that someone is responding, then assess severity and begin response per the runbook.

Answer

Ignore it until morning because it's off-hours

Answer

Start a postmortem immediately

Answer

Immediately escalate to the incident commander

Question 11

A company uses Cloud Monitoring SLO monitoring with error budget alerts. They set a slow burn alert with a 5x burn rate over a 6-hour window. If the error budget is 0.1% over 30 days, approximately how long would it take to exhaust the budget at a 5x burn rate?

Accepted Answer

6 days. At 5x burn rate, the budget lasts 1/5 of the SLO period. 30 days / 5 = 6 days. The 6-hour window is used to detect this burn rate early.

Answer

12 hours

Answer

6 hours

Answer

30 days

Question 12

Which Google Cloud service can be used to automate repetitive operational tasks such as restarting a VM or clearing a cache, as part of toil reduction?

Accepted Answer

Cloud Functions. Cloud Functions is a serverless execution environment that can be triggered by events or schedules to automate tasks. It is well-suited for automating simple operational tasks.

Answer

Compute Engine

Answer

Cloud Run

Answer

Cloud Build

Question 13

An SRE team wants to implement chaos engineering on their GKE cluster. Which TWO options are valid tools or services for injecting faults into GKE workloads?

Accepted Answer

Chaos Mesh. Chaos Mesh is a dedicated chaos engineering platform for Kubernetes. Traffic Director's HTTP fault filter can inject faults at the proxy level for services within a mesh. Both can be used on GKE.

Answer

Cloud Audit Logs

Answer

Cloud Endpoints

Answer

Cloud Scheduler

Question 14

A company wants to set up error budget alerting in Cloud Monitoring for a service with a 99.9% SLO over 30 days. They want to receive alerts when the error budget burn rate reaches certain thresholds. Which TWO of the following are typical recommendations for alerting thresholds?

Accepted Answer

14x burn rate over 1 hour. Common SRE practice uses a fast burn alert (e.g., 14x burn rate over 1 hour) and a slow burn alert (e.g., 5x burn rate over 6 hours) to cover both rapid and gradual budget consumption.

Answer

100x burn rate over 1 minute

Answer

2x burn rate over 1 day

Answer

1x burn rate over 30 days

Question 15

During a postmortem, an SRE team identifies several contributing factors. Which THREE items should be included in the action items section of a blameless postmortem?

Accepted Answer

Verification steps to confirm the fix is effective. Action items should be specific, have an owner, and a due date. Assigning blame or vague plans are not appropriate. The items should address systemic issues.

Answer

Generic recommendations like 'improve testing'

Answer

Assign blame to the engineer who caused the incident