PCD Practice Test 4 — 25 Questions

Question 1

A company needs to store petabytes of time-series IoT sensor data and query it with single-digit millisecond latency at millions of reads per second. The data has a simple key-value structure with timestamps. Which Google Cloud database is MOST appropriate?

Accepted Answer

Cloud Bigtable. Cloud Bigtable is a fully managed, scalable NoSQL database designed for large analytical and operational workloads, making it ideal for petabyte-scale time-series IoT sensor data. It supports single-digit millisecond latency for reads and writes at millions of operations per second through its underlying storage engine (based on Google's Chubby and SSTable technology) and its native integration with the HBase API, which provides efficient key-value access with timestamp-based versioning.

Answer

BigQuery

Answer

Firestore

Answer

Cloud Spanner

Question 2

A company running a high-traffic e-commerce platform on Google Cloud experiences occasional data loss in their Cloud SQL database during failover events. The database is configured with a failover replica in a different zone. What is the most likely cause of the data loss?

Accepted Answer

The database is using asynchronous replication to the failover replica.. Cloud SQL uses synchronous replication for failover replicas by default, ensuring that transactions are committed on both the primary and the replica before acknowledging the write. If asynchronous replication is configured, the replica may lag behind the primary, and during a failover, any transactions not yet replicated are lost. This is the most likely cause of data loss during failover events.

Answer

Automated backups are not enabled.

Answer

The failover replica is configured as a read replica instead of a failover replica.

Answer

The database is not using regional persistent disks.

Question 3

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.. Option B is correct because 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 4

You need a fully managed, relational OLTP database that is PostgreSQL-compatible and can run analytical queries on the same data without extract-transform-load (ETL). Which Google Cloud database should you use?

Accepted Answer

AlloyDB. AlloyDB is a fully managed, PostgreSQL-compatible database service designed for both transactional (OLTP) and analytical workloads on the same data without requiring ETL. It achieves this through its AlloyDB Columnar Engine, which automatically accelerates analytical queries by storing data in a columnar format while maintaining full PostgreSQL compatibility for OLTP operations.

Answer

Cloud Bigtable

Answer

Cloud SQL for PostgreSQL

Answer

Cloud Spanner

Question 5

An application running on Cloud Run experiences cold starts causing latency spikes. What is the most cost-effective solution to reduce cold starts?

Accepted Answer

Set a minimum number of instances. Setting a minimum number of instances ensures that Cloud Run always keeps at least one instance warm (idle) to serve incoming requests instantly, eliminating cold start latency. This is the most cost-effective solution because you only pay for the minimum instances when they are idle (at a reduced rate), whereas other options increase per-request cost or do not address the root cause of cold starts.

Answer

Increase the container's CPU allocation

Answer

Enable HTTP keep-alive connections

Answer

Use a larger container memory size

Question 6

A mobile app team wants to store user session state with low latency and support for pub/sub messaging. They need a managed service that automatically scales. Which database is BEST suited for this?

Accepted Answer

Memorystore for Redis. Memorystore for Redis is the best choice because it provides an in-memory data store with sub-millisecond latency, ideal for session state caching, and natively supports pub/sub messaging via Redis Pub/Sub. As a managed service, it automatically handles scaling and failover, meeting the team's requirements without operational overhead.

Answer

Bigtable

Answer

Cloud SQL

Answer

Firestore

Question 7

Which Google Cloud database service is serverless, supports mobile and web apps with offline data synchronization, and provides document-level security rules?

Accepted Answer

Firestore. Firestore is a serverless, NoSQL document database that automatically scales, supports mobile and web clients with offline data persistence and synchronization via its SDKs, and enforces document-level security rules through Firebase Security Rules. This combination of serverless scaling, offline sync, and granular security makes it the correct choice for the described requirements.

Answer

Memorystore

Answer

Cloud Bigtable

Answer

Cloud Spanner

Question 8

A company is building a real-time analytics application on Google Cloud that ingests data from thousands of IoT devices. The data must be processed with sub-second latency and stored in a time-series database for querying. Which combination of services provides the best scalability and availability?

Accepted Answer

Cloud Pub/Sub, Cloud Dataflow, Cloud Bigtable. Cloud Bigtable is a fully managed, scalable NoSQL database designed for large analytical and operational workloads, offering sub-10ms latency for time-series data. Combined with Cloud Pub/Sub for ingesting high-throughput IoT data and Cloud Dataflow for stream processing, this combination provides the best scalability and availability for real-time analytics with sub-second latency requirements.

Answer

Cloud Pub/Sub, Cloud Dataflow, Cloud Datastore

Answer

Cloud Pub/Sub, Cloud Functions, Cloud SQL

Answer

Cloud Pub/Sub, Cloud Dataflow, Cloud Storage

Question 9

You have a Cloud Spanner database with a table that has a secondary index. You notice that queries using the index are performing a back join to the base table. Which index feature can you use to avoid this back join?

Accepted Answer

Use the STORING clause to include the queried columns in the index. In Cloud Spanner, a secondary index does not store all columns of the base table by default. When a query uses the index but needs columns not present in the index, Spanner performs a back join (also called a table lookup) to retrieve those missing columns from the base table. The STORING clause allows you to include additional non-key columns in the index itself, making the index covering and eliminating the need for the back join.

Answer

Use a composite primary key to include those columns

Answer

Use a local secondary index instead of a global one

Answer

Use interleaving with the base table

Question 10

An e-commerce platform uses Cloud SQL for PostgreSQL for its inventory database. To meet a higher availability requirement, they decide to enable the HA configuration. What is the expected recovery point objective (RPO) with Cloud SQL HA?

Accepted Answer

0 (zero). Cloud SQL for PostgreSQL HA uses synchronous replication to a standby instance in a different zone within the same region. This ensures that every write transaction is committed on both the primary and standby before acknowledging the client, resulting in zero data loss upon failover. Therefore, the RPO is 0 (zero).

Answer

Depends on the replication lag

Answer

Up to 5 minutes

Answer

Up to 1 minute

Question 11

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 12

An organization wants to cache frequently accessed session data for a web application to reduce database load. They require sub-millisecond latency and support for pub/sub messaging. Which Google Cloud service should they use?

Accepted Answer

Memorystore for Redis. Memorystore for Redis is the correct choice because it provides an in-memory data store with sub-millisecond latency, ideal for caching frequently accessed session data. It also natively supports pub/sub messaging via Redis's built-in PUBLISH/SUBSCRIBE commands, meeting both requirements precisely.

Answer

Cloud SQL

Answer

Cloud Bigtable

Answer

Firestore

Question 13

You need to design a Firestore database for a mobile chat application that supports real-time updates and offline access. The app requires that users can only read and write their own messages. Which three configurations should you implement? (Choose three.)

Accepted Answer

Enable offline persistence in the client SDK. Option A is correct because enabling offline persistence in the Firestore client SDK allows the mobile chat app to cache data locally, ensuring that users can read and write their own messages even when the device is temporarily offline. This is essential for a chat application that must support real-time updates and offline access, as Firestore automatically synchronizes local changes with the server when connectivity is restored.

Answer

Use Cloud SQL instead of Firestore for stronger consistency

Answer

Use Firestore Datastore mode

Question 14

A company runs a stateful application on Compute Engine instances with local SSDs. They need to perform maintenance that requires stopping the instances. What is the best approach to ensure data durability and minimal downtime?

Accepted Answer

Migrate data to persistent disks and configure the application to use persistent disks. Local SSDs provide ephemeral storage that is tied to the lifecycle of the Compute Engine instance. When an instance is stopped or terminated, data on local SSDs is permanently lost. To ensure data durability during maintenance that requires stopping the instance, the application must use persistent disks, which are durable network-attached storage that persists independently of the instance. Option D is correct because migrating the application to persistent disks ensures data survives the stop and allows the instance to be restarted with the same data, minimizing downtime.

Answer

Create a snapshot of the local SSD before stopping the instance

Answer

Use instance groups with autohealing to automatically recreate instances

Answer

Enable live migration on the instance

Question 15

A company is designing a highly available application on Google Cloud using multiple regions. Which TWO strategies should they implement to achieve this?

Accepted Answer

Use a global load balancer to distribute traffic across regions.. Option B is correct because a global load balancer (e.g., Google Cloud External HTTPS Load Balancer) can distribute traffic across multiple regions, providing cross-region failover and low-latency routing. This is a fundamental pattern for multi-region high availability, as it allows traffic to be directed to healthy backends in any region, even if an entire region fails.

Answer

Use zonal persistent disks for stateful data.

Answer

Deploy a single instance group in one region for simplicity.

Answer

Store all data in a single Cloud Storage bucket.

Question 16

Which TWO statements about building container images for Google Cloud Run are correct? (Choose TWO.)

Accepted Answer

The container must respond to health checks on the same port as the main application.. Option B is correct because Cloud Run requires the container to respond to health checks (e.g., HTTP GET /health) on the same port as the main application. Cloud Run uses the same port for both user requests and health check probes; if the health check fails, the container is restarted. This ensures the container is always ready to serve traffic.

Answer

The container must use HTTP/1.1; HTTP/2 is not supported.

Answer

The container must listen on port 8080 by default.

Answer

The container must run as root user.

Question 17

Which THREE steps are required to set up a CI/CD pipeline for Cloud Run using Cloud Build and GitHub? (Choose THREE.)

Accepted Answer

Enable the Cloud Build, Cloud Run, and Artifact Registry APIs.. Options A, B, and D are required. Option C is optional; Cloud Build can connect to GitHub without a mirror. Option E is wrong because Artifact Registry is used, not Container Registry (deprecated).

Answer

Push the container image to Container Registry.

Answer

Mirror the GitHub repository to Cloud Source Repositories.

Question 18

A developer is building a CI/CD pipeline for a microservices application. The pipeline should build a container image, run unit tests, and deploy to Google Kubernetes Engine (GKE) only if all tests pass. Which Google Cloud service is best suited for orchestrating this pipeline?

Accepted Answer

Cloud Build. Cloud Build is the correct choice because it is a fully managed CI/CD platform that natively supports building container images, running unit tests, and deploying to GKE. It can be configured with a cloudbuild.yaml file to define steps for building, testing, and deploying, and it only proceeds to the deploy step if all prior steps (including tests) succeed. This makes it the best fit for orchestrating the entire pipeline in a single, integrated service.

Answer

Compute Engine

Answer

Cloud Run

Answer

Cloud Functions

Question 19

A developer needs to build a CI/CD pipeline that automatically tests and deploys a Node.js application to Cloud Run whenever a pull request is merged to the main branch. Which Google Cloud service should be used to trigger the pipeline?

Accepted Answer

Cloud Build. Cloud Build is the correct service because it is Google Cloud's fully managed CI/CD platform that can automatically trigger pipeline executions in response to repository events, such as a pull request merge to the main branch. By configuring a Cloud Build trigger with a source repository (e.g., Cloud Source Repositories, GitHub, or Bitbucket), the developer can define build steps to test the Node.js application and deploy it to Cloud Run using the `gcloud run deploy` command or a dedicated builder. This makes Cloud Build the native and most direct choice for building, testing, and deploying to Cloud Run in a single automated pipeline.

Answer

Cloud Functions

Answer

Cloud Deploy

Answer

App Engine

Question 20

A developer runs the above command and cloudbuild.yaml. The build fails at the deploy step with a permission error. The developer has the Cloud Build Editor role on the project. What is the likely cause?

Accepted Answer

The Cloud Build service account lacks the Cloud Run Admin role.. The Cloud Build Editor role grants permissions to submit builds and execute build steps, but the actual execution of those steps (including the deploy step) runs under the Cloud Build service account. By default, this service account does not have the Cloud Run Admin role, which is required to deploy to Cloud Run. Without this role, the `gcloud run deploy` command fails with a permission error.

Answer

The Cloud Build Editor role does not have permission to submit builds.

Answer

The Docker image is not in a format compatible with Cloud Run.

Answer

The build step uses the 'gcloud' command without authentication.