PCD Practice Test 5 — 10 Questions

Question 1

You need to select a Google Cloud database for a global e-commerce platform that requires strong consistency for inventory updates, but can tolerate eventual consistency for product reviews. Which THREE services would you consider appropriate for the different parts of the platform?

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

Accepted Answer

Bigtable for real-time user behavior tracking. Bigtable is correct for real-time user behavior tracking as it is a fully managed, scalable NoSQL database designed for high-throughput, low-latency workloads, providing strong consistency for single-row operations. Firestore is suitable for product reviews because it supports eventual consistency for multi-region queries, meeting the tolerance requirement, while offering strong consistency within a single region. Cloud Spanner is ideal for inventory data because it provides global strong consistency and ACID transactions, crucial for inventory accuracy across regions.

Answer

BigQuery for storing product reviews

Answer

Cloud SQL for inventory

Question 2

Refer to the exhibit. A developer runs the above command to deploy a Cloud Function triggered by Pub/Sub. The function fails to execute when a message is published. The logs show: "Function execution took 60001 ms, finished with status: 'timeout'". What should the developer do?

Accepted Answer

Check the function code for long-running operations. The timeout error indicates the Cloud Function is exceeding its maximum execution duration. The default timeout for Cloud Functions is 60 seconds, and the logs confirm the function ran for 60001 ms before being forcibly terminated. The most likely cause is that the function code contains long-running operations (e.g., synchronous HTTP calls, database queries, or heavy computation) that do not complete within the allotted time. Therefore, the developer should inspect and optimize the function code to reduce execution time, such as by using asynchronous processing or breaking the work into smaller chunks.

Answer

Change the trigger to HTTP

Answer

Reduce the number of function instances

Answer

Increase the function timeout to 9 minutes

Question 3

Refer to the exhibit. A Cloud Build config deploys a new image to GKE. After the build succeeds, the pods restart with the new image but the application configuration is unchanged. What is the most likely cause?

Accepted Answer

The ConfigMap is not updated with the new configuration values.. A is correct because a Cloud Build config that deploys a new image to GKE does not automatically update the ConfigMap. The pods restart with the new image, but the application configuration remains unchanged because the ConfigMap still holds the old values. To apply new configuration, the ConfigMap must be updated separately, and the pods must be restarted or redeployed to pick up the changes.

Answer

The deployment rollout strategy is set to Recreate, causing downtime.

Answer

The new image is not being pulled because of imagePullPolicy: IfNotPresent.

Answer

The GKE cluster does not have sufficient permissions to pull from Container Registry.

Question 4

A company runs a Java microservice on GKE that processes financial transactions. The service is critical and must meet a 99.9% availability SLO. They have set up Cloud Monitoring alerting policies based on request latency and error rate. Recently, the team noticed that the alerting policy for high latency fires too frequently with false positives, causing alert fatigue. They want to reduce false positives without compromising real issues. The latency metric is collected from the application's custom metric via Prometheus. Which approach should they take?

Accepted Answer

Increase the alert duration to require sustained latency over a longer period.. Increasing the alert duration requires the high latency to be sustained over a longer period, which filters out transient spikes that cause false positives. This approach preserves the ability to detect genuine, prolonged performance degradation that could impact the 99.9% availability SLO, without raising the threshold and risking missed real issues.

Answer

Change the metric to use median instead of average.

Answer

Increase the alert threshold to a higher latency value.

Answer

Disable the alert and rely on manual checks.

Question 5

A team is designing a disaster recovery plan for a critical application on Google Cloud. The application runs on Compute Engine with a regional persistent disk. They want to minimize data loss in case of a regional outage. Which strategy should they use?

Accepted Answer

Use persistent disk snapshot replication to another region. Persistent disk snapshot replication to another region is the correct strategy because snapshots are stored in Cloud Storage and can be replicated across regions. This allows you to restore the disk from a snapshot in a different region if the primary region experiences an outage, minimizing data loss by ensuring the backup is geographically separate. Regional persistent disks are synchronous within a region but do not provide cross-region replication, so snapshots are the recommended approach for cross-region disaster recovery.

Answer

Create a snapshot schedule and store snapshots in the same region

Answer

Use synchronous replication across regions

Answer

Configure a managed instance group with autohealing

Question 6

A startup is migrating a 100 GB PostgreSQL database from a self-managed VM to Cloud SQL. They want zero downtime during cutover. Which TWO features of Database Migration Service should they use?

Accepted Answer

Promote the Cloud SQL replica to standalone instance for cutover.. Continuous migration with CDC enables cutover with minimal downtime. Promoting the replica is the final step to make Cloud SQL the primary with zero downtime.

Answer

Use Cloud SQL Auth Proxy for source connectivity.

Answer

Use VPC peering to connect source to Cloud SQL.

Answer

One-time migration job.

Question 7

Refer to the exhibit. A developer notices that instance-3 is in TERMINATED state. What is the most likely reason?

Accepted Answer

The instance had automatic restart disabled. When an instance's 'automatic restart' is disabled, the instance will not be automatically restarted after a host maintenance event or a failure. If the underlying host experiences an issue, the instance transitions to TERMINATED state instead of being migrated or restarted. This is the most likely reason for instance-3 being in TERMINATED state while other instances remain running.

Answer

The instance was deleted

Answer

The instance was preempted

Answer

The instance's zone was unavailable

Question 8

You have a Cloud Bigtable instance with a single table that stores user events. You need to ensure that data older than 30 days is automatically deleted. What should you configure?

Accepted Answer

Set a garbage collection policy on the default column family to delete cells older than 30 days. Bigtable garbage collection policies operate on column families and can delete cells older than a specified time or keep a max number of versions.

Answer

Set a time-to-live (TTL) on the table

Answer

Use a cron job to manually delete rows with timestamps older than 30 days

Answer

Enable compaction and set a TTL on the table

Question 9

A company is migrating an on-premises PostgreSQL database to Cloud SQL for PostgreSQL using Database Migration Service (DMS). During the continuous migration phase, the source database has high write throughput, and the DMS job is falling behind. The replication lag is increasing over time. What should the engineer do to reduce lag?

Accepted Answer

Increase the wal_keep_segments parameter on the source and enable parallel apply on the destination Cloud SQL instance. Increasing wal_keep_segments on the source ensures that more WAL segments are retained, preventing DMS from failing to fetch required logs due to premature cleanup. Enabling parallel apply on the Cloud SQL destination allows multiple transactions to be applied concurrently, reducing the time needed to catch up with the source's high write throughput.

Answer

Change the source database to use synchronous replication with DMS

Answer

Reduce the maximum WAL size (max_wal_size) on the source to generate smaller logs

Answer

Increase the maintenance_work_mem parameter on the source database

Question 10

A company needs a fully managed, globally distributed relational database that supports ACID transactions across regions. Which Google Cloud service should they choose?

Accepted Answer

Cloud Spanner. Cloud Spanner is the only Google Cloud database that is fully managed, globally distributed, and supports ACID transactions. Cloud SQL is regional. Bigtable is NoSQL and does not support ACID transactions. Firestore is a document database with limited transaction support but not globally distributed in the same way.

Answer

Firestore

Answer

Cloud Bigtable

Answer

Cloud SQL