PCD Practice Test 18 — 15 Questions

Question 1

A company runs a critical financial application on Google Cloud using Compute Engine instances in a managed instance group (MIG) with auto-scaling based on CPU utilization. The application stores state in a local SSD and relies on sticky sessions (session affinity). Recently, during a traffic spike, the MIG scaled out new instances, but some users lost their sessions because the load balancer routed them to a different instance. The team needs to maintain session persistence without sacrificing scalability. What should they do?

Accepted Answer

Implement a shared session store using Cloud Memorystore for Redis.. Option A is correct because using Cloud Memorystore for Redis provides a centralized, external session store that decouples session state from individual Compute Engine instances. This ensures that any instance in the managed instance group can serve any user's request, maintaining session persistence even as the MIG scales out or in based on CPU utilization. It preserves scalability because the session store is independent of instance lifecycle, and Redis offers low-latency reads and writes suitable for session data.

Answer

Increase the instance group's cooldown period to reduce scaling frequency.

Answer

Use a global HTTPS Load Balancer with cookie-based session affinity.

Answer

Use Cloud NAT for consistent source IP routing.

Question 2

A developer is using Cloud Spanner for a global application. They need to design a schema to avoid hotspots. Which practice should they follow?

Accepted Answer

Use a hash prefix on the primary key. Option D is correct because Cloud Spanner uses a distributed architecture that splits data across splits based on the primary key. A monotonically increasing or timestamp-based key causes all new writes to hit a single split, creating a hotspot. By using a hash prefix on the primary key, writes are distributed uniformly across all splits, avoiding hotspots and maximizing write throughput.

Answer

Use a UUID primary key

Answer

Use a monotonically increasing primary key

Answer

Use a composite primary key with a timestamp

Question 3

A media company wants to serve video content globally with low latency and high throughput. Which Google Cloud service is best suited?

Accepted Answer

Cloud CDN. Cloud CDN leverages Google's global edge cache network to deliver video content from locations closest to end users, minimizing latency and offloading origin servers. It integrates with Cloud Load Balancer and Cloud Storage to provide high-throughput, low-latency streaming without requiring users to manage caching infrastructure.

Answer

Cloud Load Balancer

Answer

Cloud Storage with public bucket

Answer

App Engine

Question 4

A company is using Cloud Run for a stateless API. They want to ensure that the service can handle sudden traffic spikes. Which two features should they configure?

Accepted Answer

Enable container concurrency.. Option A is correct because enabling container concurrency allows a single Cloud Run container instance to handle multiple requests simultaneously, up to the configured concurrency limit (default 80, max 1000). This improves throughput and resource utilization during traffic spikes without requiring additional instances. Option D is correct because setting max instances to a high value ensures the service can scale out to handle sudden load by creating more container instances, up to the configured maximum, preventing cold starts and request queuing.

Answer

Use Cloud Load Balancing.

Answer

Enable CPU always on allocation.

Answer

Set min instances to zero to save cost.

Question 5

A team runs a microservice on Compute Engine behind a regional external HTTP load balancer. They want to automatically replace unhealthy instances without manual intervention. Which feature should they use?

Accepted Answer

Managed instance group with autoscaling and health check. A managed instance group (MIG) with autoscaling and a health check is the correct choice because it automatically replaces unhealthy instances based on the health check results. The MIG uses the health check to detect failed instances, then automatically recreates them from the instance template, ensuring high availability without manual intervention. Autoscaling further adjusts the number of instances based on load, but the core replacement mechanism is driven by the MIG's health check and autohealing feature.

Answer

Unmanaged instance group with health check

Answer

Instance template with manual replacement

Answer

Load balancer backend service health check only

Question 6

A company runs a microservices application on Google Kubernetes Engine. They use Cloud SQL for persistent data. Recently, during a traffic spike, the application experienced increased latency and some requests failed with timeout errors. The team observed that the Cloud SQL CPU utilization spiked to 100%, and the GKE pods had high memory usage. They are using a standard Cloud SQL tier (db-n1-standard-2). Which course of action would best improve the application's performance and reliability?

Accepted Answer

Implement caching with Memorystore for frequently accessed data.. The correct answer is D because the primary bottleneck is the Cloud SQL CPU spiking to 100% under heavy read traffic. Implementing Memorystore (Redis) caching offloads repeated read queries from the database, reducing CPU load and query latency. This directly addresses the root cause—database CPU exhaustion—without requiring a larger database instance or adding replicas that would still be limited by the same CPU.

Answer

Upgrade Cloud SQL to a higher tier with more CPU.

Answer

Increase the number of replicas in GKE to reduce load per pod.

Answer

Add read replicas to Cloud SQL.

Question 7

You are deploying a stateful application to GKE. The deployment fails with an error: 'pods failed to fit in any node due to insufficient CPU'. The cluster has 3 nodes with 4 vCPUs each. The deployment requests 2 vCPUs per pod with 5 replicas. What is the most likely issue?

Accepted Answer

Other workloads or system components are consuming CPU resources.. Option D is correct because the total requested CPU (10 vCPUs) exceeds cluster capacity (12 vCPUs), but there might be other pods or system reservations. Option A is wrong because resources are specified. Option B is wrong because taints are not mentioned. Option C is wrong because cluster autoscaler is not failing to scale, the error indicates insufficient capacity.

Answer

The cluster autoscaler is not enabled.

Answer

The deployment does not specify resource limits.

Answer

The nodes have taints that prevent pod scheduling.

Question 8

A team is deploying a new version of an application on GKE using a rolling update. They want to ensure that the update proceeds only if the new pods are healthy. Which two steps should they include? (Choose two.)

Accepted Answer

Set the minReadySeconds field in the deployment.. Option A is correct because setting `minReadySeconds` in a Deployment ensures that a newly created Pod is considered ready only after it has been stable for that duration, preventing the rolling update from proceeding if the Pod fails shortly after startup. Option B is correct because a readiness probe determines whether a Pod is ready to serve traffic; during a rolling update, the Deployment controller waits for the new Pod's readiness probe to succeed before scaling down old Pods, ensuring the update only continues when new Pods are healthy.

Answer

Define a liveness probe for the container.

Answer

Set the revisionHistoryLimit to 10.

Answer

Use a postStart lifecycle hook to test health.

Question 9

A company deploys a stateful application using StatefulSets on GKE. They need to store persistent data on regional persistent disks for high availability. However, during zonal failures, pods are not rescheduled quickly. What is the best approach to improve recovery time?

Accepted Answer

Configure podDisruptionBudget and use persistent disk with regional replication.. Option B is correct because configuring a podDisruptionBudget ensures that a minimum number of Pods remain available during voluntary disruptions, while using regional persistent disks (which replicate data across zones) allows the StatefulSet controller to quickly reschedule Pods in another zone without waiting for the failed zone's disk to become available. This combination minimizes downtime during zonal failures by maintaining quorum and ensuring data is already accessible in the surviving zone.

Answer

Increase the number of replicas in the StatefulSet.

Answer

Use a headless service with external persistent storage like Filestore.

Answer

Use a Deployment instead of StatefulSet.

Question 10

A developer deploys a service on Cloud Run with a concurrency setting of 1. The service makes external API calls. Under heavy load, the service starts returning 503 errors. What is the most likely cause?

Accepted Answer

Instance concurrency is too low causing request queuing and timeout.. With concurrency=1, each instance handles one request at a time, so many requests cause many instances to spin up, possibly hitting max instances limit and causing 503s. Option C is correct. Option A doesn't cause 503s. Option B is about quota, but concurrency is more direct. Option D is external.

Answer

The container image is too large.

Answer

The Cloud Run service is hitting the maximum number of requests per second limit.

Answer

The API endpoint rate limits the requests.

Question 11

A company deploys a stateful application on GKE using a StatefulSet with PersistentVolumeClaims (PVCs). After a node failure, the pod is rescheduled to another node but the PVC remains in 'Pending' state. What is the most likely reason?

Accepted Answer

The PV's claimRef still points to the old PVC UID and is in Released state.. Option D is correct because the PersistentVolume (PV) is in 'Released' state and cannot be reused without manual intervention. Option A is wrong because the PVC is not bound to a PV. Option B is wrong because pod rescheduling does not delete PV. Option C is wrong because reclaim policy can be Retain or Delete.

Answer

The PVC is bound to a PV that is still attached to the failed node.

Answer

The StorageClass has reclaimPolicy: Delete so the PV was deleted.

Answer

The StatefulSet's pod management policy prevents reattachment.

Question 12

A team is deploying a microservice on Cloud Run that requires environment variables with sensitive information, such as database passwords. What is the recommended way to provide these secrets?

Accepted Answer

Use Secret Manager to store the secrets and refer to them in the Cloud Run service.. Secret Manager is the recommended service for storing and accessing sensitive data like passwords. Access via environment variable or volume mount. Storing in source code or Cloud Storage without encryption is insecure.

Answer

Inject them directly in the Cloud Run YAML configuration.

Answer

Embed them in the container image as environment variables.

Answer

Store them in a Cloud Storage bucket and mount as a volume.

Question 13

A developer is troubleshooting a deployment on Cloud Run. The service fails with 'Container failed to start' error. The container image is built from a Dockerfile that uses CMD ['npm', 'start']. What is the most likely cause?

Accepted Answer

The application does not listen on the port specified by the PORT environment variable.. Cloud Run requires the containerized application to listen on the port specified by the PORT environment variable (default 8080). If the application is hardcoded to listen on a different port (e.g., 3000) or does not read the PORT variable, Cloud Run's health checks and routing will fail, resulting in a 'Container failed to start' error. The CMD instruction is correct for starting npm, but the application must bind to the correct port.

Answer

The Dockerfile uses CMD instead of ENTRYPOINT.

Answer

The container image is too large and exceeds the memory limit.

Answer

The Cloud Run service does not have permission to pull the image from Container Registry.

Question 14

A developer is deploying a microservice on GKE that needs to be accessible only from within the same VPC network. The microservice must have a stable, internal IP address that does not change when pods are updated. Which options should be used?

Accepted Answer

Use a Service of type LoadBalancer with the annotation 'cloud.google.com/load-balancer-type: Internal'.. Option C is correct because deploying a Service of type LoadBalancer with the annotation 'cloud.google.com/load-balancer-type: Internal' creates an internal TCP/UDP load balancer within the VPC network. This provides a stable, internal IP address that persists across pod updates, as the load balancer's IP is independent of the underlying pods and is managed by Google Cloud's networking layer.

Answer

Use a Service of type NodePort with a static reservation.

Answer

Use a Service of type ClusterIP with a static IP.

Answer

Use a Service of type ExternalName pointing to the pods' internal IPs.

Question 15

Which THREE are valid methods for authenticating a user or service when deploying a Cloud Function via the Google Cloud SDK? (Choose 3)

Accepted Answer

Using a user account with 'gcloud auth login'. Option B is correct because 'gcloud auth login' authenticates a user account via OAuth 2.0, which is a valid method for deploying Cloud Functions. The Google Cloud SDK uses the user's credentials to authorize API calls, including deployments, making this a standard authentication approach for interactive or user-driven workflows.

Answer

Using an API key

Answer

Using an OAuth 2.0 client ID