PCD Practice Test 3 — 30 Questions

Question 1

A developer wants to run a single test suite across multiple environments (dev, staging, prod) using Cloud Build. What is the best practice?

Accepted Answer

Use a single Cloud Build trigger with substitutions to parameterize the environment.. Cloud Build triggers support substitutions (e.g., `$_ENV`) that allow a single trigger to parameterize the environment variable, enabling the same test suite to run across dev, staging, and prod without duplicating configuration. This aligns with Infrastructure as Code (IaC) principles and reduces maintenance overhead.

Answer

Use Cloud Deploy to run tests in each environment.

Answer

Use separate branches for each environment.

Answer

Create separate Cloud Build triggers for each environment.

Question 2

An organization runs a stateful application on GKE that uses PersistentVolumes. They want to perform a rolling update of the application without disrupting the underlying persistent data. What should they use?

Accepted Answer

A StatefulSet with a PersistentVolumeClaim template.. A StatefulSet is the correct choice because it is designed for stateful applications that require stable, unique network identifiers and persistent storage. By including a PersistentVolumeClaim template in the StatefulSet spec, each Pod gets its own dedicated PersistentVolume that persists across rescheduling and rolling updates, ensuring data is not disrupted.

Answer

A ReplicaSet with a headless service.

Answer

A DaemonSet with a PodDisruptionBudget.

Answer

A Deployment with a PersistentVolumeClaim template.

Question 3

A company is designing a polyglot persistence architecture. They need to use Cloud SQL for transactions, Bigtable for real-time analytics, and BigQuery for reporting. They also need to keep data across these systems eventually consistent. Which TWO approaches should they use?

Accepted Answer

Implement a saga pattern with compensating transactions for each write.

Answer

Use two-phase commit across all databases.

Answer

Use Cloud Spanner as a single database to avoid polyglot complexity.

Answer

Write to all three databases in a single transaction using distributed transactions.

Question 4

You are designing a Cloud Bigtable schema for a time-series application. To optimize performance and avoid hot spots, which THREE row key design practices should you follow? (Choose 3)

Accepted Answer

Place the highest cardinality field (e.g., device ID) first in the row key. Reversing timestamps, salting keys, and promoting high-cardinality fields to the start of the row key are recommended to distribute writes evenly.

Answer

Use a single table for all data

Answer

Use sequential integers as row keys

Question 5

You need to migrate an on-premises MySQL 5.7 database (2 TB) to Cloud SQL for MySQL with minimal downtime. Database Migration Service (DMS) is chosen. What is the correct sequence of steps to ensure a successful continuous migration?

Accepted Answer

Set up a connection profile for the source, create a DMS migration job (full dump + CDC), monitor the initial dump, then promote the replica to complete migration.. DMS continuous migration first performs a full dump (initial snapshot), then switches to CDC to replicate ongoing changes. After the initial dump, you validate the replica and promote it to make it the primary. The correct order: create connection profile for source, create migration job with full dump + CDC, monitor initial dump, then promote when ready.

Answer

Use mysqldump to export the database, import to Cloud SQL, then set up DMS for CDC only.

Answer

Create a DMS continuous migration job directly without a connection profile.

Answer

First promote the Cloud SQL replica, then create the connection profile.

Question 6

An online gaming platform uses Cloud Spanner as its globally distributed database. They notice that write latency increases significantly during peak hours. The application performs many single-row writes with high consistency requirements. Which design change would most effectively reduce write latency?

Accepted Answer

Use interleaved tables to colocate related rows.. Interleaved tables in Cloud Spanner physically colocate parent and child rows, reducing the number of splits and cross-node round trips for related single-row writes. This minimizes distributed transaction overhead and write latency, especially under high consistency requirements, without requiring additional nodes or sacrificing consistency.

Answer

Increase the number of nodes in the Spanner instance.

Answer

Switch to eventual consistency mode for writes.

Answer

Split the table into multiple smaller tables.

Question 7

Match each Google Cloud service to its primary purpose.

Accepted Answer

Cloud Run: A fully managed compute platform for containerized applications.. Cloud Run deploys containers, Cloud Functions runs event-driven functions, and Cloud Storage stores unstructured objects. Common confusions include swapping the definitions of Cloud Run and Cloud Functions, or mistaking Cloud Storage for a database service like Cloud SQL.

Answer

Cloud Run: A serverless execution environment for building and connecting cloud services.

Answer

Cloud Storage: A fully managed relational database for MySQL, PostgreSQL, and SQL Server.

Question 8

A team uses Cloud Build to build and deploy a Node.js application to App Engine flexible environment. The build succeeds, but the deployment fails with 'ERROR: (gcloud.app.deploy) Error Response: [9] Application startup error!' The team checks logs and sees 'Error: Module not found: 'express''. What is the most likely cause?

Accepted Answer

The dependencies are not installed during the build step before deploying.. The error 'Module not found: express' indicates that the Node.js dependencies (specifically the 'express' package) are not present in the deployed application. In Cloud Build, the build steps must explicitly install dependencies (e.g., via 'npm install') before the deploy step. If the build configuration does not include an 'npm install' step, the dependencies listed in package.json are not copied to the App Engine flexible environment, causing the startup error.

Answer

The build step includes 'npm test' which fails.

Answer

The Node.js version specified in app.yaml is incompatible with the dependencies.

Answer

The app.yaml file is missing from the root of the repository.

Question 9

You are migrating an on-premises Oracle database to Cloud SQL for PostgreSQL. You need to assess the migration feasibility and convert the schema. Which tools should you use?

Accepted Answer

Use Ora2Pg for schema conversion and DMS for data migration.. Ora2Pg is an open-source tool that converts Oracle schema to PostgreSQL. Database Migration Service (DMS) supports migration from Oracle to Cloud SQL for PostgreSQL. For assessment, you can use tools like Oracle Migration Toolkit or Ora2Pg's assessment mode.

Answer

Use mysqldump to export and import to PostgreSQL.

Answer

Use pg_dump to export the Oracle database and import into Cloud SQL.

Answer

Use DMS directly with Oracle source; it automatically converts schema.

Question 10

A mobile app developer wants to store user preferences and provide offline sync capabilities. The database should be serverless and automatically scale with usage. Which Google Cloud database is best suited?

Accepted Answer

Cloud Firestore. Cloud Firestore is a serverless, NoSQL document database that automatically scales with usage, making it ideal for storing user preferences and providing offline sync capabilities via its built-in offline data persistence and real-time synchronization. It supports mobile and web clients with automatic multi-region replication and strong consistency, aligning perfectly with the requirements of a mobile app developer.

Answer

Cloud Spanner

Answer

Cloud SQL

Answer

Cloud Bigtable

Question 11

A team wants to use Cloud Scheduler to trigger a Cloud Function that calls an external API every hour. The Cloud Function requires an API key for the external service. How should the team securely provide the API key to the function?

Accepted Answer

Store the API key in Secret Manager and access it via the Secret Manager API in the function code.. Secret Manager is Google Cloud's recommended service for storing secrets like API keys. It integrates natively with Cloud Functions, allowing secure access without exposing the key in environment variables or code. Option A is insecure because environment variables can be visible in the function configuration. Option C is insecure because hardcoding exposes the key in the source code. Option D is not the best practice; while Cloud Storage with CSEK provides encryption, it is not designed for secrets management and requires more complex access control.

Answer

Pass the API key as an environment variable in the function's runtime environment.

Answer

Hardcode the API key in the Cloud Function source code.

Answer

Store the key in Cloud Storage with customer-supplied encryption key (CSEK).

Question 12

A company is migrating a monolithic Java application to microservices on Google Kubernetes Engine (GKE). The application uses a shared MySQL database. The team wants to adopt a testing strategy that validates service interactions without deploying to a full cluster. Which testing approach is most appropriate?

Accepted Answer

Consumer-driven contract testing with tools like Spring Cloud Contract.. Consumer-driven contract testing (CDC) with tools like Spring Cloud Contract validates the interactions between microservices by defining and verifying API contracts (e.g., request/response formats, headers, status codes) without requiring a full GKE cluster. This approach is ideal for a migration from a monolithic Java application because it ensures that each service adheres to its expected behavior when communicating over HTTP or messaging, catching integration issues early in the development cycle. It does not require deploying to a cluster, making it faster and more lightweight than end-to-end testing.

Answer

Load testing to simulate production traffic.

Answer

Unit testing with mocked dependencies.

Answer

End-to-end testing in a staging environment.

Question 13

A developer wants to automatically deploy a new version of an application to App Engine Standard every time code is pushed to the main branch of a Cloud Source Repositories repository. Which service should be used?

Accepted Answer

Cloud Build. Cloud Build is the correct service because it is a fully managed CI/CD platform that integrates natively with Cloud Source Repositories and App Engine Standard. You can configure a Cloud Build trigger to automatically build and deploy your application whenever code is pushed to the main branch, using a cloudbuild.yaml file that specifies the build steps and the `gcloud app deploy` command.

Answer

Cloud Run

Answer

Cloud Scheduler

Answer

Cloud Deploy

Question 14

A Cloud Spanner database has a table Orders with a child table OrderItems. Queries often join Orders and OrderItems on OrderID. Which schema design optimizes performance for these joins?

Accepted Answer

Make OrderItems an interleaved table under Orders. Interleaved tables store child rows with their parent row in the same split, colocating related data and reducing cross-node communication. This is the correct optimization for parent-child joins.

Answer

Define a secondary index on OrderItems.OrderID

Answer

Use a global index on Orders.OrderID

Answer

Denormalize OrderItems data into the Orders table

Question 15

An operations team is configuring a Cloud Monitoring alerting policy for a critical application. They want to ensure that alerts are only fired when an anomaly persists for at least 5 minutes to reduce noise. Which condition configuration should they use?

Accepted Answer

Use a 'Metric Threshold' condition and set the 'for' parameter to 300 seconds.. The 'for' parameter in a Metric Threshold condition specifies the duration (in seconds) that a metric must continuously violate the threshold before the alert fires. Setting it to 300 seconds ensures the anomaly persists for at least 5 minutes, reducing noise from transient spikes. This is the standard approach in Cloud Monitoring for sustained condition evaluation.

Answer

Configure 'Evaluation Missing Data' to '5 minutes'.

Answer

Set the condition type to 'Metric Absence' with a 5-minute duration.

Answer

Use 'Never retrigger' state with 5-minute window.

Question 16

A team is migrating a Teradata data warehouse to BigQuery using the BigQuery Data Transfer Service. They need to schedule regular incremental transfers. What is the correct configuration for the transfer?

Accepted Answer

Create a transfer config with source type 'Teradata', target dataset, and schedule frequency.. BigQuery Data Transfer Service for Teradata supports scheduled transfers. The correct setup is to configure a transfer config with a schedule (e.g., daily) and specify the dataset and table mappings. The service handles incremental loads based on a watermark column.

Answer

Export Teradata data to Cloud Storage and use BigQuery load jobs scheduled via Cloud Scheduler.

Answer

Use Cloud Data Fusion to create a batch pipeline from Teradata to BigQuery.

Answer

Use a BigQuery scheduled query to SELECT * FROM Teradata via federated query.

Question 17

A mobile application developer needs a serverless NoSQL database that supports offline data synchronization across devices and real-time updates. Which Google Cloud database service should they use?

Accepted Answer

Firestore. Firestore is a serverless, NoSQL document database that provides built-in offline data synchronization across devices and real-time updates via snapshot listeners. It automatically handles conflict resolution and data replication, making it ideal for mobile applications that need to work offline and sync when connectivity is restored.

Answer

Cloud Bigtable

Answer

Cloud SQL

Answer

Cloud Spanner

Question 18

An e-commerce platform uses Cloud Spanner for transactions and Cloud Bigtable for session state and recommendations. They want to synchronize customer profile changes from Spanner to Bigtable in near real-time. Which three components should they use? (Choose 3)

Accepted Answer

Cloud Spanner change streams. Spanner change streams capture changes, Pub/Sub provides a scalable messaging channel, and Dataflow can transform and write to Bigtable. Cloud Functions could be used but are less suitable for high-throughput. Cloud Scheduler is batch-oriented.

Answer

Cloud Functions

Answer

Cloud Scheduler

Question 19

A team is deploying a microservice application on Google Kubernetes Engine (GKE). They want to ensure high availability and minimize downtime during rolling updates. Which TWO actions should they take? (Choose two.)

Accepted Answer

Configure pod disruption budgets to limit the number of pods that can be unavailable simultaneously.. PodDisruptionBudgets (PDBs) allow you to specify the minimum number of pods that must remain available during voluntary disruptions like rolling updates, ensuring high availability. Option D is correct because readiness probes control when a pod is added to a Service's endpoints; during rolling updates, they prevent traffic from being sent to a pod until it is ready, minimizing downtime.

Answer

Use Horizontal Pod Autoscaler to automatically adjust the number of pods based on CPU utilization.

Answer

Enable liveness probes to automatically restart pods that become unresponsive.

Answer

Enable node auto-repair to automatically replace unhealthy nodes.

Question 20

Your organization uses Cloud Functions (1st gen) to process events from Cloud Storage. Recently, you migrated to Cloud Functions (2nd gen) to take advantage of longer timeouts and concurrency. After the migration, some invocations fail with 'DeadlineExceeded' errors even though the total execution time is below the 60-minute limit. What is the most likely cause?

Accepted Answer

The function is processing multiple concurrent requests per instance, causing a single request to exceed the HTTP timeout due to contention. Cloud Functions (2nd gen) supports concurrent request processing per instance. When multiple requests are handled simultaneously by the same instance, they share the instance's resources, including the HTTP timeout. If one request consumes excessive time due to contention (e.g., waiting for CPU or I/O), other concurrent requests may hit the HTTP request timeout (default 60 minutes for 2nd gen) even if their individual execution time is shorter. This is a common issue when migrating from 1st gen (which processes one request at a time) to 2nd gen with concurrency enabled.

Answer

The function does not have enough memory allocated for the new workload

Answer

The function is being cold-started more frequently due to reduced min instances

Answer

The function timeout is still set to the 1st gen default of 9 minutes