PCD Practice Exam 52 — 20 Questions

Question 1

You are deploying a Cassandra database on GKE. Which resource type should you use to ensure stable network identities and persistent storage per pod?

Accepted Answer

StatefulSet with volumeClaimTemplates. StatefulSet is the correct resource because it provides stable, unique network identities (via headless Service and ordinal pod names) and persistent storage per pod through volumeClaimTemplates, which dynamically create PersistentVolumeClaims for each replica. This is essential for Cassandra, which requires stable node identities and dedicated storage to maintain cluster state and data consistency.

Answer

Job with persistent disk

Answer

Deployment with persistent volume claims

Answer

DaemonSet with hostPath volumes

Question 2

A company needs to run AlloyDB for PostgreSQL with a read pool that can automatically scale based on load. They also need to run a local instance on-premises for disaster recovery. Which features should they use?

Accepted Answer

Use AlloyDB with auto-scaling read pool and AlloyDB Omni for on-premises. AlloyDB read pools support auto-scaling. For on-premises disaster recovery, AlloyDB Omni provides a downloadable version that can run on-premises and replicate from the cloud. Cross-region replication is for cloud-to-cloud, not on-premises.

Answer

Use AlloyDB with read replicas in the same region and Cloud SQL for on-premises

Answer

Use AlloyDB with a single instance and use Bigtable for on-premises

Answer

Use AlloyDB with cross-region replication to another cloud region

Question 3

Which TWO statements are true about Cloud Functions? (Choose two.)

Accepted Answer

Cloud Functions automatically scale based on the number of incoming events. Cloud Functions automatically scale horizontally based on the number of incoming events, such as HTTP requests or Pub/Sub messages. The platform handles this scaling transparently, spinning up new function instances as needed to handle concurrent invocations, and scaling down to zero when idle. This is a key serverless characteristic that eliminates the need for manual capacity planning.

Answer

Cloud Functions require you to provide a container image from Container Registry

Answer

Cloud Functions can only be triggered by HTTP requests

Answer

Cloud Functions have a maximum execution timeout of 9 minutes for all runtimes

Question 4

A team is deploying a containerized application to Cloud Run. The application needs to process large files (up to 500 MB) uploaded by users. Which storage approach should they use to avoid Cloud Run's request size limit?

Accepted Answer

Use signed URLs to upload to Cloud Storage. Cloud Run has a default request size limit of 32 MB, which is far below the 500 MB files the application needs to process. Using signed URLs allows users to upload files directly to Cloud Storage, bypassing Cloud Run entirely. This approach avoids the request size limit and offloads the storage and retrieval of large files to a scalable, managed service.

Answer

Upload files directly to Cloud Run

Answer

Mount a Cloud Filestore volume

Answer

Use Cloud Functions as a proxy for uploads

Question 5

A company runs a web application on Google Kubernetes Engine (GKE) that uses Cloud SQL for its database. The application is deployed via Cloud Build and uses a custom container image stored in Artifact Registry. Recently, the development team noticed that new deployments are failing with a 'CrashLoopBackOff' error in the pod logs. The logs indicate that the application cannot connect to the Cloud SQL instance. The application uses the Cloud SQL Proxy sidecar container to connect. The Cloud SQL Proxy configuration has not changed recently. The GKE cluster is in region us-central1, and the Cloud SQL instance is in us-central1 as well. The team verified that the Cloud SQL instance is running and accepting connections from authorized networks. They also confirmed that the service account used by the pod has the 'Cloud SQL Client' role. The application has been running stable for months until a recent GKE cluster upgrade. The deployment YAML uses environment variables for database connection. The Cloud SQL Proxy is deployed as a sidecar container with command: '/cloud_sql_proxy -instances=<instance-connection-name>=tcp:5432'. The pod logs show the proxy attempting to connect but timing out. The network team confirms that there are no firewall rules blocking the connection. The Cloud SQL instance has an authorized network entry for the GKE cluster's nodes' IP range. What is the most likely cause of the connection failure?

Accepted Answer

The Cloud SQL instance is configured with a private IP and the GKE cluster is VPC-native but the Cloud SQL Proxy is configured to connect via public IP.. The Cloud SQL Proxy sidecar is configured to connect via public IP (using the instance connection name without the `-private-ip` flag), but the Cloud SQL instance is configured with a private IP. Since the GKE cluster is VPC-native, the pod can reach the private IP within the VPC, but the proxy is attempting a public IP connection, which fails because the instance's authorized networks only include the GKE nodes' IP range (public IPs of nodes), not the pod's private IP range. The recent GKE cluster upgrade may have changed the node's public IP or networking configuration, exacerbating the mismatch.

Answer

The Cloud SQL Proxy container is using an outdated version that is incompatible with the current Cloud SQL API.

Answer

The application is using a wrong database password in the connection string.

Answer

The pod's namespace does not have the Cloud SQL Proxy configuration correctly set up.

Question 6

A company is migrating an on-premises Oracle database to Cloud SQL for PostgreSQL. They require a deployment that supports up to 30,000 transactions per second (TPS) and provides automatic storage scaling. Which instance configuration should they choose?

Accepted Answer

High-memory machine type with SSD and storage auto-increase enabled. Cloud SQL supports storage auto-increase regardless of machine type. For high TPS, a high-memory machine type (e.g., highmem) provides more memory per CPU, which can improve performance for database workloads. SSD is required for consistent performance. HDD is not recommended for production.

Answer

Standard machine type with HDD and storage auto-increase enabled

Answer

Custom machine type with 4 vCPUs and 15 GB memory, SSD, and storage auto-increase enabled

Answer

Lightweight machine type with SSD and storage auto-increase disabled

Question 7

A team wants to monitor custom application metrics from a Compute Engine instance. They use the Cloud Monitoring agent. Which metric type should they use to report a gauge measurement like current memory usage?

Accepted Answer

gauge. A gauge metric type is specifically designed to report a value that can arbitrarily increase or decrease over time, such as current memory usage. The Cloud Monitoring agent supports gauge metrics for point-in-time measurements, and they are reported as a single data point without any aggregation window, making them ideal for snapshot-like observations.

Answer

histogram

Answer

delta

Answer

cumulative

Question 8

A Cloud Spanner query that uses a secondary index is taking longer than expected. The index includes a large payload column. How can the query performance be improved?

Accepted Answer

Add the payload column to the index using the STORING clause. Using the STORING clause in a secondary index stores the specified columns in the index, allowing queries to be satisfied from the index alone without a join back to the base table. This reduces read latency.

Answer

Use a composite key instead of an index

Answer

Change the index to a global index

Answer

Remove the index and use a full table scan

Question 9

A company is migrating an on-premises MySQL database to Cloud SQL. They want to minimize downtime and ensure data consistency using a one-time migration. Which approach should they use?

Accepted Answer

Create a Cloud SQL instance and use Database Migration Service with continuous replication. Database Migration Service (DMS) supports one-time migration with continuous replication until cutover, minimizing downtime.

Answer

Set up a Cloud SQL replica and promote it

Answer

Use BigQuery Data Transfer Service

Answer

Export the database using mysqldump and import into Cloud SQL

Question 10

An organization is migrating a large Oracle database to Cloud Spanner using Database Migration Service. They need to convert stored procedures and functions from PL/SQL to Spanner's SQL dialect. What is the best approach?

Accepted Answer

Refactor the application to handle business logic outside the database using client libraries.. Spanner does not support stored procedures; the recommended approach is to migrate business logic to the application layer using client libraries, which provides better scalability and maintainability.

Answer

Use Ora2Pg to convert PL/SQL to PL/pgSQL and deploy to Cloud Spanner.

Answer

Migrate the PL/SQL code as-is; Cloud Spanner supports Oracle PL/SQL.

Answer

Manually rewrite PL/SQL as Spanner stored procedures.

Question 11

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 set to 1, each Cloud Run instance can handle only one request at a time. Under heavy load, new requests must wait for an available instance, and if the queue wait time exceeds the request timeout (default 5 minutes, max 60 minutes), the requests are dropped with a 503 HTTP status. This is the most direct cause of the 503 errors, as the service cannot scale fast enough or the queue depth exceeds limits.

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 12

You are deploying a Node.js application on Cloud Run. The container image is stored in Artifact Registry. After deploying with gcloud run deploy, the revision fails with 'Container failed to start. Failed to start and then listen on the port defined by the PORT environment variable.' The application listens on port 8080 by default. The Dockerfile uses EXPOSE 8080. The Cloud Run service is configured with container port 8080. You have verified that the container starts locally using docker run -p 8080:8080. What is the most likely cause of the startup failure?

Accepted Answer

The application is hardcoded to listen on port 8080 but the Cloud Run environment variable PORT may override it to a different value.. Cloud Run sets the PORT environment variable to 8080 by default, but if the application is hardcoded to listen on 8080 instead of reading PORT, it may fail if the variable is not set or incorrect. Option B is wrong because the DEFAULT port variable is not used. Option C is wrong because the container port is set correctly. Option D is wrong because port 8080 is not privileged.

Answer

The application is trying to bind to a privileged port.

Answer

The Cloud Run service is configured with container port 443 by default.

Answer

The container does not have a proper HEALTHCHECK instruction.

Question 13

A company deploys a Java application on Compute Engine with a preemptible VM instance group managed by an instance template. The application writes critical state to local SSD. After a preemption event, the new instance starts fresh and loses state. What is the best practice to ensure state persistence?

Accepted Answer

Refactor the application to write state to a persistent service like Cloud Storage. Local SSD data is ephemeral and lost on VM preemption or termination. Refactoring the application to write critical state to a persistent service like Cloud Storage ensures data durability independent of the VM lifecycle. This aligns with the best practice of designing preemptible workloads to be stateless, where state is stored externally.

Answer

Modify the startup script to recover state from a snapshot

Answer

Configure the managed instance group as stateful to preserve local SSD data

Answer

Use a regular (non-preemptible) VM instead of preemptible

Question 14

A team is migrating a monolithic application to a microservices architecture on Google Kubernetes Engine (GKE). They want to ensure that failures in one microservice do not cascade to others. Which design pattern should they implement?

Accepted Answer

Implement a circuit breaker pattern that opens when failure thresholds are exceeded.. The circuit breaker pattern is the correct choice because it prevents cascading failures by monitoring inter-service calls and opening the circuit when failures exceed a threshold, allowing the system to fail fast and recover gracefully. In a GKE-based microservices architecture, this pattern is typically implemented using libraries like Resilience4j or Istio's circuit breaker, which can be configured to trip after a certain number of consecutive failures, thus protecting downstream services from being overwhelmed.

Answer

Implement retry logic with exponential backoff for all inter-service calls.

Answer

Use synchronous HTTP calls with timeouts to detect failures quickly.

Answer

Use bulkheads to separate thread pools for each service.

Question 15

A company uses Cloud SQL for PostgreSQL as its primary database. They want to query this data from BigQuery for analytics without moving the data. They also need to ensure that BigQuery queries see the most recent data (within seconds of changes). Which approach is most suitable?

Accepted Answer

Set up Datastream to continuously replicate data from Cloud SQL to BigQuery, then query BigQuery tables.. BigQuery federated queries via external tables can directly query Cloud SQL without data movement. However, for near real-time freshness, the best approach is to use Datastream to replicate changes from Cloud SQL to BigQuery in near real-time. Federated queries alone have higher latency (minutes) and are not suitable for sub-second freshness.

Answer

Create a Cloud Function that queries Cloud SQL every 5 seconds and writes results to BigQuery.

Answer

Use BigQuery federated queries to create an external table connected to Cloud SQL.

Answer

Use a scheduled query in BigQuery that exports Cloud SQL data to Cloud Storage and loads into BigQuery.

Question 16

A company is deploying a microservices-based application on Google Kubernetes Engine (GKE). The application consists of several stateless services that experience unpredictable traffic spikes. The team wants to ensure high availability and scalability while minimizing costs. Which design should they implement?

Accepted Answer

Deploy a Regional GKE cluster with cluster autoscaling and Horizontal Pod Autoscaler for each deployment.. A Regional GKE cluster provides multi-zone high availability, cluster autoscaling dynamically adjusts node pool size to handle unpredictable traffic spikes, and Horizontal Pod Autoscaler (HPA) scales individual pod replicas based on CPU/memory or custom metrics. This combination ensures both scalability and cost efficiency by only provisioning resources when needed.

Answer

Deploy a Regional GKE cluster with node auto-provisioning and a fixed number of replicas per service.

Answer

Use a Regional GKE cluster with preemptible VMs and static pod counts.

Answer

Use a single-zone GKE cluster with a large fixed node pool to handle peak load.

Question 17

A company runs a stateful application on Compute Engine with regional persistent disks. They want to achieve high availability with automatic failover in case of a zone failure. Which architecture meets these requirements?

Accepted Answer

Use regional persistent disks with a managed instance group spanning two zones. Regional persistent disks synchronously replicate data across two zones, and when combined with a managed instance group (MIG) spanning those same two zones, the application can automatically fail over to the healthy zone if one zone fails. The MIG's autohealing and health-check mechanisms detect the failure and recreate instances in the surviving zone, while the regional PD remains accessible from either zone, ensuring high availability without manual intervention.

Answer

Use Cloud Storage FUSE to mount a multi-regional bucket as a filesystem

Answer

Use standard persistent disks with scheduled snapshots to a multi-region bucket

Answer

Use zonal persistent disks with a managed instance group in a single zone

Question 18

A company is designing a cloud-native application on Google Cloud that requires low-latency access to a global user base. The application serves static content and dynamic APIs. Which strategy best minimizes latency while maintaining high availability?

Accepted Answer

Use Cloud CDN to cache static content and deploy the API across multiple regions with global load balancing.. It combines Cloud CDN for caching static content at edge locations worldwide, reducing latency for static assets, and deploys the dynamic API across multiple regions with global load balancing (using Google Cloud's global external HTTP(S) load balancer) to route users to the nearest healthy backend, minimizing latency for dynamic requests while ensuring high availability through regional redundancy.

Answer

Deploy the application in a single region and use Cloud Interconnect for global access.

Answer

Use Cloud Armor to protect the application and rely on Google's backbone for low latency.

Answer

Store all content in Cloud Storage and serve directly from there.

Question 19

A developer wants to run integration tests against a Cloud Spanner emulator in a local development environment. What is the best way to set up the emulator?

Accepted Answer

Run the Cloud Spanner emulator Docker container and set the SPANNER_EMULATOR_HOST environment variable.. The Cloud Spanner emulator is distributed as a Docker container, and the recommended way to run it locally is to start that container and set the `SPANNER_EMULATOR_HOST` environment variable (e.g., `localhost:9010`) so that the Spanner client library redirects all API calls to the emulator instead of the production service. This provides a fully functional, in-memory Spanner instance for integration testing without incurring costs or requiring network access to GCP.

Answer

Use a mock library instead of an emulator.

Answer

Use the Cloud Spanner API directly without an emulator.

Answer

Install the emulator using `gcloud emulators spanner start`.

Question 20

An engineer is migrating a large on-premises SQL Server database to Cloud SQL for PostgreSQL. They need to continuously replicate changes during the migration to minimize downtime. Which Database Migration Service job type should they use?

Accepted Answer

Continuous migration. DMS offers continuous migration jobs that perform a full dump followed by CDC, enabling near-zero-downtime cutover.

Answer

Bulk migration

Answer

Scheduled migration

Answer

One-time migration