PCD Practice Test 16 — 15 Questions

Question 1

Refer to the exhibit. The alert fires when what happens?

Accepted Answer

When the rate of responses on App Engine exceeds 10 per second for 5 minutes. The alert is configured to fire when the rate of responses on App Engine exceeds 10 per second for a sustained period of 5 minutes. This is a rate-based threshold, not a cumulative count or latency metric, which is why option A correctly describes the condition.

Answer

When the cumulative response count on App Engine exceeds 10 for 5 minutes

Answer

When the latency exceeds 10 seconds for 5 minutes

Answer

When the response rate drops below 10 per second for 5 minutes

Question 2

A company is deploying a microservices application on Google Kubernetes Engine (GKE) and needs to ensure that services can discover each other without hardcoding IP addresses. Which approach should they use?

Accepted Answer

Use Cloud DNS with Kubernetes Services of type ClusterIP. Kubernetes Services of type ClusterIP provide a stable virtual IP and DNS name (via Cloud DNS) that resolves to the service's ClusterIP, enabling pods to discover each other without hardcoding IP addresses. GKE integrates with Cloud DNS to automatically register service DNS names in the format ..svc.cluster.local, allowing microservices to communicate reliably even if pods are rescheduled or IPs change.

Answer

Use environment variables injected into each pod

Answer

Use a ConfigMap to store service endpoints

Answer

Use Cloud Load Balancing to route traffic between services

Question 3

A developer wants to ensure their Cloud Function is reliable. Which three testing practices should they follow? (Choose three.)

Accepted Answer

Write unit tests that mock external services. Unit tests should mock external services (like databases or APIs) to isolate the function's logic and avoid dependencies on live infrastructure. This ensures tests are fast, deterministic, and do not incur costs or side effects from actual service calls.

Answer

Deploy the function to production for integration testing

Answer

Perform load testing using a Cloud Scheduler job that invokes the function frequently

Question 4

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.

Question 5

A company needs to back up a Cloud Bigtable instance daily and be able to restore it to a different region in case of a regional outage. What is the recommended approach?

Accepted Answer

Create a Bigtable managed backup of the cluster and restore it to a cluster in the desired region. Bigtable managed backups are the recommended approach for disaster recovery across regions. They allow you to create a consistent backup of a Bigtable cluster and restore it to a different cluster in another region, ensuring data durability and recoverability in case of a regional outage. This method is fully managed, does not require custom code, and preserves the table schema and data integrity.

Answer

Use Cloud Scheduler to trigger a Dataflow job that exports the Bigtable table to Avro files in GCS, then import in another region

Answer

Use Bigtable replication with a multi-cluster routing policy

Answer

Export the table using the HBase shell to a Cloud Storage bucket and import it in the new region

Question 6

A team is building a serverless event-driven application using Cloud Functions and Cloud Pub/Sub. The function processes messages from a Pub/Sub subscription and writes results to Firestore. During peak hours, the function experiences high latency and some messages are being retried multiple times. Which three steps should the team take to improve reliability and scalability? (Choose three.)

Accepted Answer

Enable retry policy on the Pub/Sub subscription to automatically retry failed messages.. Enabling a retry policy on the Pub/Sub subscription ensures that messages that fail to be processed (e.g., due to transient errors or timeouts) are automatically retried. This prevents message loss and improves reliability by allowing the Cloud Function to reprocess messages without manual intervention. The retry policy works with the subscription's acknowledgement deadline, so messages are redelivered if not acknowledged in time.

Answer

Batch multiple Pub/Sub messages into a single Cloud Function invocation.

Answer

Increase the Cloud Function timeout to the maximum allowed value.

Question 7

Refer to the exhibit. The function returns 'Error' even though the document exists. What is the most likely reason?

Accepted Answer

The document ID in the query parameter is URL-encoded and needs to be decoded using `decodeURIComponent`.. The most likely reason is that the document ID in the query parameter is URL-encoded, and the function does not decode it before using it as a Firestore document reference. Firestore document IDs are case-sensitive and must match exactly; a URL-encoded string like 'doc%20name' will not match the actual document 'doc name', causing the update to fail and return 'Error'. Using `decodeURIComponent` on the parameter before passing it to Firestore resolves this.

Answer

The function has insufficient IAM permissions for Firestore.

Answer

The Firestore emulator is not running.

Answer

The `update` method requires that the document exists.

Question 8

A company is migrating a 5 TB SQL Server database to Cloud SQL for SQL Server using Database Migration Service (DMS). After the full dump phase, the continuous replication (CDC) phase starts. The team notices that the source database transaction log is growing rapidly and the CDC phase is failing intermittently with 'log space' errors. What should they do?

Accepted Answer

Increase the size of the source transaction log and ensure it is not limited. The intermittent 'log space' errors during CDC indicate that the source transaction log is running out of space to record changes for replication. Database Migration Service (DMS) requires sufficient log space to capture ongoing changes; increasing the log size and removing any size limits ensures the log can grow to accommodate the replication lag without failing.

Answer

Reduce the retention period for the source transaction log backups

Answer

Shrink the source transaction log to free up space

Answer

Switch the source database to simple recovery model to reduce logging

Question 9

A developer needs to ensure that environment variables containing secrets are securely passed to a Cloud Function during deployment. Which approach should they use?

Accepted Answer

Use Secret Manager. Secret Manager is the recommended Google Cloud service for securely storing and accessing secrets such as API keys, passwords, and certificates. It provides encryption at rest and in transit, fine-grained IAM access control, and versioning, allowing the Cloud Function to reference secrets by name at deployment time without exposing them in source code or configuration files.

Answer

Store in source code

Answer

Use Cloud KMS

Answer

Use runtime environment variables

Question 10

A company is building a microservice that processes incoming HTTP requests, performs some business logic, and writes results to Firestore. The service has variable traffic with occasional spikes. The development team wants to minimize cold start latency and prefers to use a containerized application with a custom runtime. Which compute option should they choose?

Accepted Answer

Cloud Run. Cloud Run is the correct choice because it runs containerized applications in a fully managed, serverless environment that automatically scales to zero and can handle variable traffic with occasional spikes. It minimizes cold start latency by keeping instances warm when traffic is expected, and it supports custom runtimes via Docker containers, meeting the team's requirement for a containerized application with a custom runtime.

Answer

Compute Engine

Answer

App Engine Standard

Answer

Cloud Functions (1st gen)

Question 11

A developer deploys the above app.yaml to App Engine standard environment. The deployment succeeds, but the application fails to connect to the database. What is the most likely reason?

Accepted Answer

The application is trying to connect to a local database on localhost, which is not available in the App Engine sandbox.. In App Engine standard environment, applications run in a sandboxed environment that does not support connections to a local database on localhost. The application code is attempting to connect to a database at 127.0.0.1 or localhost, which is not available in the sandbox. Instead, the application must connect to a Cloud SQL instance using a Unix socket or a private IP, or use a fully managed database service like Firestore.

Answer

The runtime 'python39' is not supported in App Engine standard environment.

Answer

The $PORT environment variable is not set in App Engine standard environment.

Answer

The entrypoint command is incorrect because gunicorn is not allowed.

Question 12

A company runs a stateful microservice that requires read-after-write consistency but can tolerate some latency for writes. They are currently using a single Cloud SQL instance and want to scale read traffic. Which approach should they take?

Accepted Answer

Enable Cloud SQL read replicas. Cloud SQL read replicas are the correct choice because they provide an asynchronous read-only copy of the primary instance, which can scale read traffic without compromising the read-after-write consistency required by the stateful microservice. The primary instance handles all writes, ensuring strong consistency for writes, while replicas serve stale reads that eventually become consistent, which aligns with the tolerance for write latency.

Answer

Use Cloud Memorystore to cache reads

Answer

Shard the database manually

Answer

Use Cloud Bigtable

Answer

Migrate to Cloud Spanner

Question 13

A company is migrating an on-premises PostgreSQL database to Google Cloud. They need high availability with automatic failover and zero RPO. Which Cloud SQL configuration should they choose?

Accepted Answer

Cloud SQL HA instance (regional). Cloud SQL HA instances use synchronous replication to a standby in the same region, providing automatic failover and zero RPO.

Answer

Cloud SQL with cross-region replication

Answer

Cloud SQL read replica in a different region

Answer

Single zone Cloud SQL instance with automated backups

Question 14

A company is building a real-time leaderboard for an online game using Memorystore for Redis. They need to support millions of concurrent users, update scores frequently, and retrieve top 100 players. Which TWO features should they use? (Choose 2.)

Accepted Answer

Sorted sets with ZADD and ZREVRANGE commands. Sorted sets are ideal for leaderboards. Redis Cluster provides horizontal scaling for high throughput. Pub/sub is for messaging, not leaderboard. Replication provides HA but not scaling.

Answer

Pub/sub channels for score updates

Answer

Keyspace notifications to detect score changes

Answer

Redis Sentinel for automatic failover

Question 15

Which Google Cloud database service is fully serverless and can scale to zero when not in use, making it cost-effective for variable workloads?

Accepted Answer

Firestore. Firestore is serverless and scales automatically, including scaling to zero. Cloud SQL and Memorystore require provisioned capacity. Bigtable requires provisioned nodes.

Answer

Cloud SQL

Answer

Memorystore

Answer

Cloud Bigtable