PCD Practice Test 9 — 10 Questions

Question 1

A startup is building a social media application with a global user base. They need a database that can handle millions of concurrent users, provide strong consistency, and scale horizontally. They expect high write throughput and need to run complex SQL queries. Which database is most suitable?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Cloud Spanner. Cloud Spanner is the only GCP database that provides horizontal scaling, strong consistency, and SQL capabilities for high write throughput globally.

Answer

Cloud Bigtable

Answer

Firestore

Answer

AlloyDB

Question 2

A company runs a stateful application on Compute Engine instances with persistent disks. The application must be highly available and be able to recover from a zonal failure with minimal data loss. The current architecture uses a single instance in one zone. Which design should the team implement?

Accepted Answer

Use a regional persistent disk attached to a managed instance group across two zones.. A regional persistent disk synchronously replicates data across two zones, and when attached to a managed instance group (MIG) spanning those zones, it provides automatic failover with minimal data loss. This design ensures that if one zone fails, the MIG can detach the disk from the failed instance and attach it to a healthy instance in the surviving zone, preserving state with near-zero RPO.

Answer

Use a standard persistent disk and configure a global load balancer to failover.

Answer

Create a snapshot schedule and restore the snapshot to a new instance in another zone on failure.

Answer

Migrate to Cloud Filestore for shared file storage across zones.

Question 3

A company is using Cloud Build for CI and wants to store build artifacts in Artifact Registry. They want to ensure that only successful builds are promoted to production. What should they do?

Accepted Answer

Use Cloud Build steps that push to Artifact Registry only if all previous steps succeed by using `waitFor` and checking exit codes.. Cloud Build steps run sequentially and only if previous steps succeed by default, so pushing to Artifact Registry only if tests pass. Option A is not sufficient because builds on main can still fail. Option C involves manual intervention. Option D is incorrect as it ignores build status.

Answer

Use Cloud Build to deploy to a staging environment, then manually promote to production.

Answer

Use Cloud Build triggers with a condition that only builds on the main branch are deployed.

Answer

Use Cloud Build with a custom script that pushes regardless of build status.

Question 4

Drag and drop the steps to configure a Cloud CDN with a Cloud Load Balancer in the correct order.

Accepted Answer

Create a Cloud Storage bucket, then create an external HTTP(S) load balancer with the bucket as a backend, then enable Cloud CDN on the backend bucket, then update DNS records to point to the load balancer's IP.. Cloud CDN is enabled on a backend bucket of a load balancer, then DNS is configured.

Answer

Create a Cloud Storage bucket, then enable Cloud CDN on the bucket, then create an external HTTP(S) load balancer with the bucket as a backend, then update DNS records.

Answer

Create an external HTTP(S) load balancer, then create a Cloud Storage bucket, then enable Cloud CDN on the bucket, then update DNS records.

Answer

Enable Cloud CDN on a bucket, then create an external HTTP(S) load balancer, then add the bucket as a backend, then update DNS records.

Question 5

A startup is building a REST API on Cloud Run. They expect unpredictable traffic spikes and want to ensure the service can scale from 0 to many instances automatically. What scaling configuration should they use?

Accepted Answer

Set min instances to 0 and max instances to 1000.. Cloud Run's autoscaling allows min instances to be set to 0, enabling the service to scale down to zero when idle (cost-efficient), and max instances to 1000 to handle unpredictable traffic spikes by scaling out horizontally. This configuration ensures the service can start from zero and automatically add instances up to the maximum limit as demand increases, which is ideal for unpredictable workloads.

Answer

Set max instances to 1 to control costs.

Answer

Use manual scaling with a fixed number of instances.

Answer

Set min instances to 5 and max to 100.

Question 6

A financial services company uses BigQuery for analytics but needs to store transactional data with strong consistency and sub-millisecond latency. They are considering Cloud SQL, Cloud Spanner, Bigtable, Memorystore, and Firestore. Which service meets all requirements?

Accepted Answer

Cloud Spanner. Cloud Spanner is the only Google Cloud service that provides both strong consistency and sub-millisecond latency for transactional workloads. It uses TrueTime for global strong consistency and supports ACID transactions with low latency. Cloud SQL offers strong consistency but cannot achieve sub-millisecond latency at scale due to single-region limits. Bigtable provides low latency but only eventual consistency. Memorystore is a caching layer, not a transactional database. Firestore provides strong consistency but typically does not guarantee sub-millisecond latency for high-throughput transactional data, especially under financial workload requirements.

Answer

Cloud SQL

Answer

Bigtable

Answer

Memorystore

Answer

Firestore

Question 7

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

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Cloud Storage with public bucket

Answer

App Engine

Question 8

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 Google Cloud's dedicated service for securely storing and managing sensitive data like API keys and database passwords. Cloud Run natively integrates with Secret Manager, allowing you to reference secret versions by name in your service configuration without exposing the secret value in plaintext. This approach ensures secrets are encrypted at rest and in transit, and access can be tightly controlled via IAM permissions.

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 9

A Cloud Run service experiences high latency under load. The service is a Node.js Express app that processes requests sequentially due to a global mutex. What is the most effective solution?

Accepted Answer

Remove the mutex and ensure request handling is asynchronous. The root cause is that the global mutex forces sequential processing, negating Node.js's asynchronous event loop. Removing the mutex and ensuring asynchronous request handling (e.g., using async/await or Promises) allows the single-threaded event loop to interleave I/O-bound tasks, dramatically reducing latency under concurrent load. This directly addresses the bottleneck without changing the underlying infrastructure.

Answer

Use Cloud Run for Anthos to handle load

Answer

Increase the number of CPUs per container

Answer

Increase the 'max-instances' setting

Question 10

A company is designing a web application that must scale horizontally to handle variable traffic. Which two practices should they implement to ensure the application is stateless and can scale without issues?

Accepted Answer

Offload session state to the user's browser using encrypted cookies.. To achieve statelessness, session state should either be stored in an external cache (e.g., Memorystore) or offloaded to the client (e.g., using cookies). Sticky sessions tie a client to a specific instance, preventing scaling. Using a database like Cloud SQL for session persistence creates a bottleneck. Regional managed instance groups improve availability but do not directly address statelessness.

Answer

Persist session data in Cloud SQL to ensure durability.

Answer

Deploy the application across multiple regional managed instance groups.

Answer

Use sticky sessions to maintain client affinity.