PCDOE Managing service incidents Practice Test 3 — 15 Questions

Question 1

Refer to the exhibit. You are reviewing an alert policy for CPU utilization. What is a potential problem with this configuration?

Accepted Answer

The duration is too short, which may cause noise during spikes.. Option B is correct because a short duration in a CPU utilization alert policy means the threshold must be breached for only a brief period before triggering an incident. This can cause noise during transient spikes that are not indicative of a sustained problem, leading to false positives and alert fatigue for operations teams.

Answer

The autoClose time is too long.

Answer

The threshold is set too low.

Answer

The combiner should be 'AND'.

Question 2

Refer to the exhibit. Your team deployed a new revision to Cloud Run. After deployment, error rates increased. You want to roll back to the previous revision, which is still serving. Which command should you use?

Accepted Answer

gcloud run services update-traffic my-service --to-revisions=my-service-00001-caz=100. Option A is correct because `gcloud run services update-traffic` allows you to precisely control traffic splitting between revisions. By setting `--to-revisions=my-service-00001-caz=100`, you direct 100% of incoming requests to the previous revision, effectively rolling back without deleting the current revision. This command is the standard method for traffic-based rollbacks in Cloud Run.

Answer

gcloud run services rollback my-service

Answer

gcloud run revisions delete my-service-00002-caw

Answer

gcloud run deploy my-service --image gcr.io/my-project/my-image:v1

Question 3

A team is experiencing increased latency in their microservices application after a new deployment. They suspect a specific service is the bottleneck. Which tool should they use to identify the slowest service in the request path?

Accepted Answer

Cloud Trace. Cloud Trace is the correct tool because it provides end-to-end latency analysis by capturing trace spans from each microservice in a request path. It aggregates and visualizes the time spent in each service, allowing you to pinpoint the slowest service causing the bottleneck. This directly addresses the need to identify the specific service responsible for increased latency after a deployment.

Answer

Cloud Profiler

Answer

Cloud Logging

Answer

Cloud Monitoring

Question 4

During an incident, a DevOps engineer needs to temporarily increase the capacity of a Google Kubernetes Engine (GKE) cluster to handle the traffic surge. Which approach minimizes manual intervention and follows Google best practices?

Accepted Answer

Enable cluster autoscaler and update the horizontal pod autoscaler to scale faster.. Option A is correct because enabling the cluster autoscaler automatically adjusts the number of nodes in the node pool based on resource demands, while updating the horizontal pod autoscaler (HPA) to scale faster (e.g., reducing the stabilization window or increasing the target CPU utilization threshold) allows pods to replicate more quickly. This combination minimizes manual intervention by automating both pod-level and node-level scaling, aligning with Google's best practices for handling traffic surges in GKE.

Answer

Manually add a node pool with larger machines via the Google Cloud Console.

Answer

Create a new node pool and migrate pods using kubectl drain.

Answer

Scale the existing node pool by increasing the maximum node count in the cluster.

Question 5

A company uses Error Budgets for their service. The SLO is 99.9% availability over a 30-day window. The service has been down for 30 minutes in the current window. What is the remaining error budget?

Accepted Answer

13.2 minutes. The SLO of 99.9% over a 30-day window allows a total error budget of 43.2 minutes (30 days × 24 hours × 60 minutes × 0.001). The service has already consumed 30 minutes of downtime, so the remaining error budget is 43.2 - 30 = 13.2 minutes. Option C is correct because it reflects this precise calculation.

Answer

43.2 minutes

Answer

60 minutes

Answer

30 minutes

Question 6

A team has configured an uptime check with a 5xx threshold alert. During an incident, the alert fires with severity 'critical'. The team mitigates the issue, but the alert keeps firing for 15 more minutes due to a slow-responding downstream dependency. What should the team do to avoid false alarms in future incidents?

Accepted Answer

Increase the 'duration' field in the alerting policy to require the condition to be true for a longer time before alerting.. Option B is correct because increasing the 'duration' field in the alerting policy ensures that the condition (e.g., 5xx errors) must persist for a longer, defined period before the alert fires. This prevents false alarms from transient issues like a slow-responding downstream dependency that temporarily triggers the threshold but resolves before the alert duration expires. In Google Cloud Monitoring, the duration parameter specifies the minimum time the condition must be true, filtering out short-lived spikes.

Answer

Add a second notification channel to send alerts to a different team.

Answer

Modify the alert condition to check only for 5xx errors and ignore other status codes.

Answer

Decrease the check frequency to every 30 seconds to get faster feedback.

Question 7

A DevOps engineer is troubleshooting a production incident where users are getting 502 errors from a Google Cloud HTTP(S) Load Balancer. The backend service is a GKE deployment. Initial checks show the backend pods are healthy and responding. What is the most likely cause?

Accepted Answer

The load balancer's health check is failing on the backend instance group due to mismatch between health check port and backend port.. A 502 error from an HTTP(S) Load Balancer indicates that the load balancer is unable to establish a successful connection to the backend. Even though the backend pods are healthy and responding, the load balancer's health check may be failing because it is configured to check a different port (e.g., the health check port) than the port the backend service is actually serving traffic on (e.g., the backend port). This mismatch causes the load balancer to mark the backend instances as unhealthy, resulting in 502 errors for users.

Answer

The backend pods are out of memory and crashing.

Answer

The IAM permissions for the load balancer service account are misconfigured.

Answer

The backend service has been accidentally deleted by another engineer.

Question 8

After deploying a new version of a Cloud Run service, the team notices an increase in 5xx errors. They want to quickly revert to the previous version while minimizing user impact. What is the recommended approach?

Accepted Answer

Use Cloud Run's traffic management to set 100% of traffic to the previous revision.. Cloud Run supports traffic splitting between revisions, allowing you to instantly route 100% of traffic to the previous revision without redeploying. This minimizes user impact because the rollback is immediate and does not require rebuilding or re-pulling container images. Option D is correct because it leverages Cloud Run's built-in traffic management feature for zero-downtime rollbacks.

Answer

Set the minimum number of instances of the new revision to 0.

Answer

Redeploy the previous version from the container registry.

Answer

Modify the ingress settings to restrict traffic to the new revision.

Question 9

A multinational company runs an application on Google Cloud with an SLO of 99.99% monthly availability. They use a multi-region deployment with Cloud Load Balancing and Cloud Spanner. During a regional outage in us-central1, traffic fails over to us-east1. However, the incident response team is not alerted because the error budget burn rate remained below the alert threshold. What should the team change to ensure timely alerting for such regional failures?

Accepted Answer

Create a custom dashboard and alert for regional unavailability using Cloud Monitoring metrics like load_balancing/backend_request_count and region health checks.. Option D is correct because implementing a 'signals of possible trouble' dashboard and alerts for regional failures provides early warning even before SLO is breached. Option A is wrong because lowering the burn rate alert threshold may cause noise but could help, but it's not the best practice for regional failures. Option B is wrong because the burn rate is already calculated over a longer window; reducing window might help but could increase noise. Option C is wrong because changing SLO to 99.9% would increase error budget but not address alerting.

Answer

Shorten the SLO compliance window from 30 days to 7 days.

Answer

Change the SLO to 99.9% to allow more error budget.

Answer

Reduce the error budget burn rate alert threshold from 10% to 5% per hour.

Question 10

An organization has a service that must meet a 99.99% SLO. The service runs on GKE and uses Cloud SQL. The team notices that during a major incident, the error budget is consumed rapidly. They want to implement a mechanism to automatically rollback deployments that cause sustained error budget consumption above a threshold. What is the best approach?

Accepted Answer

Set up a deployment pipeline with Cloud Deploy that includes a predeployment validation step that checks the current error budget burn rate and blocks the release if the burn rate exceeds 10% per hour.. Option A is correct because using Cloud Deploy or Spinnaker with automated rollback based on error budget burn rate is the recommended pattern. Option B is wrong because Cloud Build is CI, not deployment orchestration. Option C is wrong because canary deployments reduce blast radius but don't auto-rollback. Option D is wrong because manual rollback via Cloud Console is not automated.

Answer

Use Cloud Scheduler to run a script that checks error budget and rolls back if needed.

Answer

Implement a canary deployment strategy with manual approval steps.

Answer

Configure Cloud Build to automatically revert the last commit if error budget is consumed.

Question 11

During a post-incident review, the team discovers that a misconfiguration in Cloud Armor caused legitimate traffic to be blocked, leading to a outage. The misconfiguration was introduced by a junior engineer who had overly permissive IAM roles. What is the best way to prevent similar incidents in the future?

Accepted Answer

Use Organization Policy constraints to restrict allowed IP ranges and rules in Cloud Armor security policies.. Option D is correct because enforcing guardrails with Organization Policies can prevent misconfigurations at scale. Option A is wrong because removing the engineer's access is punitive but doesn't prevent others. Option B is wrong because peer reviews reduce human error but are not automated. Option C is wrong because Cloud Armor logs help detection but not prevention.

Answer

Enforce a mandatory peer review for all Cloud Armor configuration changes.

Answer

Revoke the junior engineer's access to Cloud Armor and grant read-only access.

Answer

Enable Cloud Armor security policy logs and create alerting for blocked traffic spikes.

Question 12

Which TWO of the following are best practices for managing incident response on Google Cloud?

Accepted Answer

Establish a clear escalation path and ensure that on-call engineers are aware of their roles.. Option B is correct because a clear escalation path with defined roles ensures that on-call engineers know exactly whom to contact for different severity levels, reducing response time and preventing miscommunication. Google Cloud's operations suite (formerly Stackdriver) supports structured escalation policies through alerting channels and notification routing, making this a foundational best practice for incident management.

Answer

Automatically escalate all incidents to the engineering manager.

Answer

Assign only one engineer to be on call to reduce confusion.

Answer

Use only one notification channel (e.g., email) to keep the team focused.

Question 13

Which THREE of the following are valid techniques for mitigating a denial-of-service (DoS) attack against a Google Cloud HTTP(S) Load Balancer?

Accepted Answer

Enable autoscaling on the backend services to handle increased load.. Option B is correct because enabling autoscaling on backend services allows the load balancer to dynamically add more backend instances in response to increased traffic, helping to absorb a DoS attack by scaling out capacity. This is a valid mitigation technique as it leverages Google Cloud's managed scaling to maintain service availability under load.

Answer

Increase the number of backend instances to absorb traffic.

Answer

Modify VPC firewall rules to block all traffic from the source IP.

Question 14

Which TWO of the following are essential elements of a comprehensive incident post-mortem document according to Google's Site Reliability Engineering (SRE) best practices?

Accepted Answer

A timeline of events leading to and during the incident.. Option B is correct because a timeline of events is a core element of an incident post-mortem in Google SRE practice, as it provides a chronological reconstruction of the incident's progression, enabling teams to understand the sequence of failures and responses. This timeline is essential for identifying contributing factors and evaluating the effectiveness of mitigation actions, not just the root cause.

Answer

Exact code line numbers and commits that caused the incident.

Answer

A detailed analysis of the root cause only.

Answer

An attribution of blame to the individual or team responsible.

Question 15

A DevOps engineer notices that a critical service is down, but no alert has been received. The engineer checks Cloud Monitoring and sees that the alerting policy appears to be correctly configured. What is the most likely cause?

Accepted Answer

The notification channel is misconfigured.. Option D is correct because if the notification channel is misconfigured (e.g., invalid webhook URL, incorrect email address, or missing PagerDuty integration key), Cloud Monitoring will correctly detect the incident but fail to deliver the alert. The engineer sees the alerting policy appears correct because the policy itself is valid, but the channel configuration prevents the notification from reaching the recipient.

Answer

The metrics for the service are not being collected.

Answer

The incident was created but automatically closed.

Answer

The SLO is defined too loosely, so the error budget is not exhausted.

PCDOE Managing service incidents Practice Test 3 — 15 Questions

Exhibit

PCDOE Managing service incidents Practice Test 3 — 15 Questions

Exhibit