Troubleshooting practice questions

A DevOps team is troubleshooting a Cloud Build pipeline that fails intermittently when building a container image. The build step uses a custom build step that runs a vulnerability scan. The error log shows: 'Step #1: Error: failed to scan image: context deadline exceeded'. The build configuration includes 'timeout: 600s'. Which is the most likely cause and solution?

Trap 1: The scan tool requires a specific dependency; add an installation…

Missing dependency would cause command not found or similar errors.

Trap 2: There is network latency between Cloud Build and the container…

Network latency would cause connection errors, not a deadline exceeded within the build.

Trap 3: The build step is running out of memory; increase the machine type…

Memory issues would produce out-of-memory errors, not timeout.

A
The scan tool requires a specific dependency; add an installation step before scanning.
Why wrong: Missing dependency would cause command not found or similar errors.
B
There is network latency between Cloud Build and the container registry; use VPC Service Controls.
Why wrong: Network latency would cause connection errors, not a deadline exceeded within the build.
C
The build step is running out of memory; increase the machine type to e2-highcpu-8.
Why wrong: Memory issues would produce out-of-memory errors, not timeout.
D
The scan step is taking longer than the build timeout; increase the timeout value in the build configuration.
The error 'context deadline exceeded' indicates the step timed out.

Question 2mediummulti select

You are an on-call engineer responding to a critical service incident affecting a production application. According to Google's Incident Management best practices, which TWO actions should you take immediately after declaring the incident?

Trap 1: Notify the incident commander to take over coordination.

The incident commander is usually designated at the start of the incident response process, often before or right at declaration, not as a separate action after declaration.

Trap 2: Begin documenting the incident for a postmortem report.

Postmortem activities are conducted after the incident is resolved, not at the start.

Trap 3: Roll back the latest deployment to the previous stable version.

Rollback should be considered only after assessing the impact and potential side effects; not an immediate first step.

A
Communicate the incident status to stakeholders and affected teams.
Communication is a key initial step to keep everyone informed and coordinated.
B
Notify the incident commander to take over coordination.
Why wrong: The incident commander is usually designated at the start of the incident response process, often before or right at declaration, not as a separate action after declaration.
C
Begin documenting the incident for a postmortem report.
Why wrong: Postmortem activities are conducted after the incident is resolved, not at the start.
D
Roll back the latest deployment to the previous stable version.
Why wrong: Rollback should be considered only after assessing the impact and potential side effects; not an immediate first step.
E
Gather evidence and logs to identify the incident's impact and root cause.
Evidence gathering is crucial to understand what is affected and to guide mitigation steps.

Question 3hardmultiple choice

You are troubleshooting a performance issue with a Compute Engine instance that is part of a managed instance group serving a web application. Users report intermittent high latency. You run the command shown in the exhibit. Based on the output, what is the most likely cause of the performance issue?

Exhibit

Refer to the exhibit.

```
$ gcloud compute instances describe instance-1 --zone=us-central1-a
...
networkInterfaces:
- accessConfigs:
  - name: external-nat
    natIP: 34.123.45.67
    type: ONE_TO_ONE_NAT
  name: nic0
  network: https://www.googleapis.com/compute/v1/projects/my-project/global/networks/default
  subnetwork: https://www.googleapis.com/compute/v1/projects/my-project/regions/us-central1/subnetworks/default
...
disks:
- autoDelete: true
  boot: true
  deviceName: instance-1
  diskSizeGb: '100'
  interface: SCSI
  source: https://www.googleapis.com/compute/v1/projects/my-project/zones/us-central1-a/disks/instance-1
  type: PERSISTENT
...
serviceAccounts:
- email: 123456789-compute@developer.gserviceaccount.com
  scopes:
  - https://www.googleapis.com/auth/devstorage.read_only
  - https://www.googleapis.com/auth/logging.write
  - https://www.googleapis.com/auth/monitoring.write
  - https://www.googleapis.com/auth/servicecontrol
  - https://www.googleapis.com/auth/service.management.readonly
  - https://www.googleapis.com/auth/trace.append
```

Trap 1: The instance is hitting the network egress bandwidth limit.

No evidence of network throttling; the instance has a standard external IP and typical egress limits for its machine type.

Trap 2: The service account lacks the necessary scopes for Cloud Monitoring…

The service account has monitoring.write and trace.append scopes, which are adequate for sending metrics and traces.

Trap 3: The boot disk is too small, causing I/O contention.

A 100GB persistent disk is sufficient for typical web server operations; disk I/O is unlikely the bottleneck unless there is heavy logging.

A
The instance is under-provisioned for CPU.
The output does not show the machine type, but the disk size and service account suggest a small instance, likely with 1 vCPU. Insufficient CPU causes high latency under load.
B
The instance is hitting the network egress bandwidth limit.
Why wrong: No evidence of network throttling; the instance has a standard external IP and typical egress limits for its machine type.
C
The service account lacks the necessary scopes for Cloud Monitoring and Cloud Trace.
Why wrong: The service account has monitoring.write and trace.append scopes, which are adequate for sending metrics and traces.
D
The boot disk is too small, causing I/O contention.
Why wrong: A 100GB persistent disk is sufficient for typical web server operations; disk I/O is unlikely the bottleneck unless there is heavy logging.

Question 4mediummulti select

A team is troubleshooting a slow response time on an App Engine standard environment application. The application uses Cloud SQL as its database. Which TWO actions should the team take to identify the bottleneck?

Trap 1: Increase the number of App Engine instances.

This may not address the root cause.

Trap 2: Enable Cloud CDN to cache responses.

Not suitable for dynamic content.

Trap 3: Disable caching to ensure fresh data.

Disabling caching worsens performance.

A
Examine App Engine request logs for latency patterns.
Correlates with slow queries.
B
Increase the number of App Engine instances.
Why wrong: This may not address the root cause.
C
Enable Cloud SQL slow query logging and analyze long-running queries.
Identifies database-level latency.
D
Enable Cloud CDN to cache responses.
Why wrong: Not suitable for dynamic content.
E
Disable caching to ensure fresh data.
Why wrong: Disabling caching worsens performance.

Question 5hardmultiple choice

A DevOps engineer is troubleshooting a Cloud Build failure. The build log shows the error: 'Permission denied for resource projects/my-project/locations/us-central1/repositories/my-repo'. The Cloud Build service account (PROJECT_NUMBER@cloudbuild.gserviceaccount.com) is used. What is the most likely missing role?

Trap 1: roles/artifactregistry.reader

This only allows reading, not writing.

Trap 2: roles/artifactregistry.admin

This is too broad and grants management permissions.

Trap 3: roles/cloudbuild.builds.builder

This is for Cloud Build execution, not for accessing Artifact Registry.

A
roles/artifactregistry.reader
Why wrong: This only allows reading, not writing.
B
roles/artifactregistry.admin
Why wrong: This is too broad and grants management permissions.
C
roles/cloudbuild.builds.builder
Why wrong: This is for Cloud Build execution, not for accessing Artifact Registry.
D
roles/artifactregistry.writer
This allows pushing artifacts to repositories.

Question 6easymulti select

A company wants to implement a DevOps culture in their new Google Cloud organization. Which THREE practices align with Google's DevOps principles? (Choose three.)

Trap 1: Use a monolithic architecture to simplify deployments.

Monoliths hinder iterative delivery.

Trap 2: Centralize all operations in a single team.

DevOps advocates cross-functional teams.

A
Monitor systems with telemetry and logs.
Observability is key.
B
Implement continuous integration and delivery.
Core DevOps practice.
C
Use a monolithic architecture to simplify deployments.
Why wrong: Monoliths hinder iterative delivery.
D
Centralize all operations in a single team.
Why wrong: DevOps advocates cross-functional teams.
E
Conduct post-mortems without blame.
Blameless culture promotes learning.

Question 7hardmultiple choice

In Google's incident management process, which role is responsible for communication with stakeholders and users during an incident?

Trap 1: Incident Commander.

The Incident Commander leads the incident response but delegates communication.

Trap 2: Technical Lead.

The Technical Lead focuses on resolving the technical issue.

Trap 3: Operations Lead.

Operations Lead is not a standard role in Google's incident management process.

A
Incident Commander.
Why wrong: The Incident Commander leads the incident response but delegates communication.
B
Communications Lead.
The Communications Lead manages all communication with stakeholders.
C
Technical Lead.
Why wrong: The Technical Lead focuses on resolving the technical issue.
D
Operations Lead.
Why wrong: Operations Lead is not a standard role in Google's incident management process.

Question 8mediummultiple choice

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?

Trap 1: The backend pods are out of memory and crashing.

Pods would be unhealthy, contradicting the scenario.

Trap 2: The IAM permissions for the load balancer service account are…

Would cause 403 errors, not 502.

Trap 3: The backend service has been accidentally deleted by another…

Would cause 'connection refused' errors, not 502.

A
The load balancer's health check is failing on the backend instance group due to mismatch between health check port and backend port.
502 errors indicate the backend is unhealthy to the load balancer.
B
The backend pods are out of memory and crashing.
Why wrong: Pods would be unhealthy, contradicting the scenario.
C
The IAM permissions for the load balancer service account are misconfigured.
Why wrong: Would cause 403 errors, not 502.
D
The backend service has been accidentally deleted by another engineer.
Why wrong: Would cause 'connection refused' errors, not 502.

Question 9easymultiple choice

A DevOps team is troubleshooting a web application that shows high latency during peak hours. The application runs on Google Kubernetes Engine (GKE). They want to identify which specific API calls are causing the delay. Which Google Cloud tool should they use?

Trap 1: Cloud Monitoring

Cloud Monitoring provides metrics but not detailed trace of individual API calls.

Trap 2: Cloud Profiler

Cloud Profiler focuses on CPU/memory consumption, not request latency.

Trap 3: Cloud Logging

Cloud Logging shows log entries but does not trace request paths across services.

A
Cloud Monitoring
Why wrong: Cloud Monitoring provides metrics but not detailed trace of individual API calls.
B
Cloud Profiler
Why wrong: Cloud Profiler focuses on CPU/memory consumption, not request latency.
C
Cloud Logging
Why wrong: Cloud Logging shows log entries but does not trace request paths across services.
D
Cloud Trace
Cloud Trace offers distributed tracing, enabling identification of slow API calls.

Question 10hardmultiple choice

Refer to the exhibit. A team is troubleshooting a pod crash loop. Based on the exhibit, which infrastructure change should be prioritized to resolve the issue and optimize service performance?

Exhibit

{
  "textPayload": "ERROR: ENOENT: no such file or directory, open '/app/data/config.txt'",
  "resource": {
    "type": "k8s_container",
    "labels": {
      "cluster_name": "prod-cluster",
      "namespace_name": "default",
      "pod_name": "api-pod-xyz"
    }
  },
  "severity": "ERROR",
  "timestamp": "2023-10-01T12:00:00Z"
}

Trap 1: Increase the pod's CPU request

CPU increase won't resolve missing file error.

Trap 2: Increase the maximum number of pods per node

Affects scheduling, not missing file.

Trap 3: Enable pod anti-affinity

Anti-affinity affects pod placement, not missing file.

A
Increase the pod's CPU request
Why wrong: CPU increase won't resolve missing file error.
B
Increase the maximum number of pods per node
Why wrong: Affects scheduling, not missing file.
C
Mount a ConfigMap or volume containing the missing file
Correct. Providing the missing file resolves the error.
D
Enable pod anti-affinity
Why wrong: Anti-affinity affects pod placement, not missing file.