PCDE Deploy scalable and highly available databases in Google Cloud Practice Test 2 — 15 Questions

Question 1

A company is designing a disaster recovery strategy for a Cloud SQL for PostgreSQL instance. They require an RPO of less than 5 minutes and an RTO of less than 2 minutes in the event of a regional outage. Which three components should they include in their solution? (Choose three.)

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

Accepted Answer

Cross-region read replica. To achieve RPO <5 minutes and RTO <2 minutes across regions, you need a solution that can recover quickly with minimal data loss. Cloud SQL cross-region read replicas replicate asynchronously, so RPO is the replication lag (which can be <5 minutes if the network is fast). Promoting a read replica manually takes minutes, but you can automate the promotion using Cloud Functions or scripts to reduce RTO. Alternatively, you could use a standby instance in another region with synchronous replication (but Cloud SQL does not support that). The best approach is to use a cross-region read replica with automated promotion (e.g., via Cloud Functions triggered by a health check). Additionally, you need to update application connection strings to point to the new primary. Using a load balancer with health checks can also help route traffic. The three correct components are: cross-region read replica, automated promotion script, and a global load balancer to redirect traffic.

Answer

Point-in-time recovery enabled with 7-day retention

Answer

Automated backup with 5-minute frequency

Question 2

A company uses Cloud Spanner with a single-region configuration in us-central1. They need to improve disaster recovery to meet an RPO of zero and an RTO of less than 5 seconds across regions. Which three actions should they take? (Choose three.)

Accepted Answer

Use backup/restore to migrate data from the single-region instance to the new multi-region instance. To achieve RPO=0 and RTO<5s across regions, you need a multi-region Spanner configuration with synchronous replication. You cannot achieve cross-region RPO=0 with a single-region instance. Therefore, you must migrate to a multi-region configuration. The steps include: 1) Create a new multi-region instance (e.g., nam6) with the desired config, 2) Migrate data from the single-region instance to the multi-region instance (e.g., using backup/restore or Dataflow), 3) Update application connection strings to point to the new instance. Optionally, you can perform a rolling migration to minimize downtime. Using cross-region read replicas is not possible for Spanner (Spanner does not have read replicas in the same sense; it uses replica types within an instance).

Answer

Add a cross-region read replica to the existing single-region instance

Answer

Enable point-in-time recovery (PITR) with 7-day retention

Question 3

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 designed for exactly this use case — petabyte-scale, low-latency (single-digit ms), high-throughput NoSQL storage for time-series, IoT, and financial data. It scales horizontally by adding nodes. BigQuery is optimised for analytics (seconds-to-minutes latency), Cloud SQL is for OLTP (limited to tens of thousands of QPS), and Firestore is for document data with hierarchical structure.

Answer

BigQuery

Answer

Cloud Spanner

Answer

Firestore

Question 4

A Cloud SQL for PostgreSQL instance needs to achieve a recovery point objective (RPO) of less than 1 minute and a recovery time objective (RTO) of less than 2 minutes in the event of a zone failure. Which disaster recovery strategy should be used?

Accepted Answer

Configure Cloud SQL HA (high availability) with a standby in a different zone.. Cloud SQL HA configuration provides automatic failover to a standby in a different zone within the same region, with RPO near zero and RTO typically under 60 seconds. Cross-region read replicas have RPO equal to replication lag (could be minutes) and RTO of minutes due to manual promotion. Cross-region backup restore has RPO equal to backup age (hours) and RTO of hours. Point-in-time recovery (PITR) is for within-region data recovery, not zone failure failover.

Answer

Perform regular backups to Cloud Storage and restore in a different zone.

Answer

Enable cross-region replication using a read replica.

Answer

Enable point-in-time recovery (PITR) with transaction log backups.

Question 5

A global e-commerce platform uses Cloud Spanner in multi-region configuration. The application writes a significant portion of traffic from Europe and requires the lowest read latency in that region. Which configuration step should be taken to minimise read latency in Europe while maintaining write availability?

Accepted Answer

Set the leader region to Europe (e.g., eur3).. In Spanner multi-region, the leader region determines where writes are committed. Setting the leader region to Europe ensures that writes are committed there, which reduces write latency for European traffic. Read-only replicas in other regions can serve reads with low latency without affecting write availability. Adding more read replicas in Europe would not reduce latency if the leader region is elsewhere. The number of read-write replicas does not directly reduce read latency. Splitting the database would not help for a single database.

Answer

Configure a separate Spanner instance for European traffic and split the database.

Answer

Add more read-write replicas in the European region.

Answer

Use a regional Spanner instance in Europe coupled with a copy of the data in Bigtable.

Question 6

A company uses Cloud Bigtable for real-time analytics. They need to implement disaster recovery across regions with a recovery point objective (RPO) of no more than 5 minutes and recovery time objective (RTO) under 10 minutes. Which approach should they take?

Accepted Answer

Configure Bigtable replication with a secondary cluster in a different region and use Cloud DNS health checks to update routing policy on failover.. Bigtable replication allows creating secondary clusters in different regions. Asynchronous replication has typical lag of a few seconds to minutes, meeting RPO of 5 minutes. For failover, the application's routing policy must be updated to point to the secondary cluster. Cloud DNS health checks can detect primary failure and automatically update routing policy. Backups have RPO equal to backup interval (hours) and RTO of hours. Exporting to Cloud Storage is manual and slow. Using Cloud Spanner is a different service.

Answer

Perform daily exports of Bigtable data to Cloud Storage and import into a new cluster in case of failure.

Answer

Migrate the workload to Cloud Spanner multi-region for built-in disaster recovery.

Answer

Use Cloud Scheduler to trigger a script that takes a Bigtable snapshot every hour.

Question 7

An engineer needs to create a backup of a Cloud SQL for MySQL instance that is retained for 400 days to meet compliance requirements. What is the correct approach?

Accepted Answer

Use Cloud SQL export to Cloud Storage and store the export for 400 days using object lifecycle management.. Cloud SQL for MySQL allows automated backups with a maximum retention of 365 days. To retain a backup for longer, the engineer must create an on-demand export to Cloud Storage. The export can be stored indefinitely. Automated backup retention cannot be extended beyond 365 days. Using Cloud SQL's backup retention setting to 400 days is not supported. Using a read replica is not a backup. Using PITR does not create a separate backup file.

Answer

Set the backup retention to 400 days in the Cloud SQL instance settings.

Answer

Create a cross-region read replica and use it as a backup source.

Answer

Use the gcloud command: gcloud sql backups create --instance=myinstance --async and rely on default retention.

Question 8

A company uses Cloud Spanner multi-region with the nam-eur-asia1 configuration. They experience a regional outage that affects two of the three regions. What is the expected behavior regarding read and write availability?

Accepted Answer

Read and write availability are unaffected because Spanner automatically fails over to remaining regions.. Spanner multi-region with 5+ regions (like nam-eur-asia1 which has 3 regions with multiple zones each) can tolerate the loss of up to two regions while maintaining read/write availability. The remaining region(s) will continue to serve reads and writes. However, if the leader region is lost, a new leader is elected from remaining regions, which may cause a brief write unavailability (RTO <1 min). Spanner guarantees 99.999% availability for multi-region instances.

Answer

Reads are available but writes are unavailable until the leader region recovers.

Answer

The entire instance becomes unavailable due to loss of quorum.

Answer

The instance becomes read-only until at least two regions recover.

Question 9

Which GCP database service automatically replicates data across multiple zones within a region and provides an SLA of 99.999% for multi-region configurations?

Accepted Answer

Cloud Spanner. Cloud Spanner is a globally distributed, strongly consistent relational database that automatically replicates data across zones. It offers 99.999% SLA for multi-region instances. Cloud SQL HA replicates across zones but has a lower SLA. Bigtable replicates asynchronously across regions but does not guarantee strong consistency. Firestore offers multi-region replication but not 99.999% SLA.

Answer

Firestore

Answer

Cloud SQL

Answer

Cloud Bigtable

Question 10

A company has a Cloud SQL for PostgreSQL instance with cross-region read replicas for disaster recovery. They want to test the failover process without affecting the primary instance. What is the recommended approach?

Accepted Answer

Promote the cross-region read replica to a standalone instance in a separate project for testing.. Cloud SQL cross-region read replicas can be promoted to a standalone instance. This promotion is a manual operation that creates a new primary instance. To test failover non-destructively, you can promote a read replica to a standalone instance in a different project or region. You can then test connectivity and read/write operations. After testing, you can either keep the promoted instance or delete it. You cannot failover and then revert the replica; promotion is irreversible. The promotion does not affect the original primary instance.

Answer

Create a clone of the primary instance and promote the clone to simulate failover.

Answer

Trigger a failover using the gcloud sql instances failover command on the primary instance.

Answer

Stop the primary instance and observe how the application behaves.

Question 11

A company uses Cloud Bigtable with replication across two regions. They want to ensure that read requests are automatically routed to the nearest available cluster with the lowest latency. Which routing policy should be configured?

Accepted Answer

Multi-cluster routing. Bigtable replication supports two routing policies: single-cluster routing and multi-cluster routing. Multi-cluster routing allows the Bigtable client to route requests to the nearest cluster based on latency, and it automatically fails over to another cluster if the first is unavailable. Any-replica routing is not a valid Bigtable policy. Read-failover routing is a Cloud DNS concept, not Bigtable. Single-cluster routing forces all requests to a specific cluster.

Answer

Single-cluster routing

Answer

Any-replica routing

Answer

Read-failover routing policy

Question 12

An application running on Compute Engine needs a relational database with high availability across zones within a single region. The application requires an RTO of less than 30 seconds and RPO of zero. Which database solution meets these requirements?

Accepted Answer

AlloyDB. AlloyDB provides automatic failover with RTO of less than 30 seconds and near-zero data loss (RPO ~0). It replicates data synchronously within a primary and read pool across zones in the same region. Cloud SQL HA has RTO <60 seconds, which does not meet the <30 second requirement. Spanner multi-region is overkill and has higher cost. Bigtable does not support SQL and has eventual consistency.

Answer

Cloud Bigtable with replication

Answer

Cloud SQL for MySQL with HA configuration

Answer

Cloud Spanner multi-region

Question 13

A company uses Cloud Spanner in a multi-region configuration with the leader region in us-central1. They want to improve write latency for users in Europe. The application's writes are latency-sensitive and must be strongly consistent. Which action should the engineer take?

Accepted Answer

Change the leader region to a European region, such as europe-west1.. In Spanner multi-region, the leader region determines where writes are committed. To reduce write latency for European users, set the leader region to a European region (e.g., europe-west1). All writes will be committed in that region, reducing round-trip time for European clients. This does not affect consistency; Spanner still provides strong consistency globally. Adding more read replicas in Europe does not affect write latency. Moving the application to Cloud SQL or Bigtable does not provide the same global strong consistency or may not meet requirements.

Answer

Add more read-only replicas in the European region.

Answer

Use a regional Spanner instance in Europe and replicate data asynchronously to the multi-region instance.

Answer

Migrate the workload to Cloud Bigtable with replication.

Question 14

A company needs to perform disaster recovery testing for their Cloud SQL for PostgreSQL instance. They want to validate that a cross-region failover works without affecting production. What is the BEST approach?

Accepted Answer

Promote a cross-region read replica to a standalone instance in the same project and test connectivity.. A read replica can be promoted to a standalone instance, which does not affect the primary instance. This allows testing read/write operations on the promoted instance. After testing, the promoted instance can be deleted or kept. Rolling back a promoted replica is not possible. Performing a failover on the primary would cause downtime. Creating a clone does not test the replication path. Testing in a separate project is not necessary.

Answer

Create a clone of the primary instance in another region and test failover to the clone.

Answer

Use the gcloud sql instances failover command on the primary instance.

Answer

Stop the primary instance and promote the read replica, then later re-promote the original primary.

Question 15

A company is designing a disaster recovery strategy for a Cloud SQL for PostgreSQL instance. They require an RPO of less than 5 minutes and an RTO of less than 2 minutes in the event of a regional outage. Which three components should they include in their solution? (Choose three.)

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

Accepted Answer

Set up Cloud DNS with a health check that updates the routing policy to the secondary cluster on failure.. To achieve DR with Bigtable, you need to configure replication to a secondary cluster in a different region. Additionally, you need to configure the application's routing to failover to the secondary cluster. Using Cloud DNS with a health check that updates the routing policy can automate traffic re-routing. Increasing the number of nodes does not provide DR. Exporting to Cloud Storage is for backup, not failover. Using Spanner is a different service.

Answer

Export Bigtable data to Cloud Storage daily and script the import into a new cluster.

Answer

Increase the number of nodes in the primary cluster to handle failover load.

Answer

Use Cloud Spanner instead of Bigtable for built-in multi-region failover.