PCDOE Design for Reliability, Scalability, and Disaster Recovery Practice Test 5 — 15 Questions

Question 1

A company runs a critical application on Cloud SQL for PostgreSQL with a 5-minute RPO and 30-minute RTO. They have a cross-region read replica for disaster recovery. During a planned failover test, what is the expected RPO and RTO when promoting the read replica?

Accepted Answer

RPO = replication lag, RTO = minutes. Cross-region read replica promotion has an RPO equal to the replication lag (data not yet replicated) and an RTO of minutes (time to promote and make writable).

Answer

RPO = 0, RTO = less than 1 minute

Answer

RPO = 0, RTO = minutes

Answer

RPO = backup age, RTO = hours

Question 2

An organization needs a multi-region database deployment with strong consistency and an RPO of zero in normal operation. They expect a regional outage and require automatic failover within seconds. Which database service and configuration meets these requirements?

Accepted Answer

Cloud Spanner multi-region configuration. Cloud Spanner multi-region configurations provide strong consistency, zero RPO during normal operation, and automatic failover within <1 minute (typically seconds) in case of regional failure.

Answer

Cloud Firestore in multi-region mode

Answer

Cloud Bigtable with multi-cluster routing and replication

Answer

Cloud SQL with cross-region read replica

Question 3

A company uses Cloud Bigtable for a real-time analytics pipeline. They have configured replication with a primary cluster in us-central1 and a secondary cluster in us-west1. They want to minimize data loss during a failover to the secondary cluster. What is the best approach to achieve the lowest possible RPO?

Accepted Answer

Use multi-cluster routing with read-failover enabled and direct all writes to the primary cluster.. Bigtable replication is asynchronous, so RPO is determined by replication lag. To minimize data loss, you should route writes to the primary cluster and use read-failover routing to consume from the secondary only when primary is unhealthy. During failover, switch writes to secondary manually.

Answer

Use single-cluster routing with failover priority set to the secondary cluster.

Answer

Use any-replica routing and let Cloud Bigtable automatically direct reads and writes to the healthiest cluster.

Answer

Use single-cluster routing and regularly back up the Bigtable data.

Question 4

You are designing disaster recovery for a globally distributed application using Cloud Spanner with a multi-region configuration. The application requires an RPO of 0 and an RTO of less than 5 seconds in the event of a full region failure. Which Spanner configuration provides these guarantees?

Accepted Answer

A multi-region Spanner instance with two read-write regions and one witness region.. A multi-region configuration with a leader region and at least two voting regions provides synchronous replication and automatic failover. Regional failover occurs within seconds, preserving zero data loss.

Answer

A single-region Spanner instance with a read replica in another region.

Answer

A multi-region Spanner instance with one read-write region and two read-only regions.

Answer

A dual-region Spanner instance using default leader placement.

Question 5

A company wants to implement a disaster recovery plan for their AlloyDB database. They need automatic failover with minimal data loss and RTO under 30 seconds. Which configuration should they use?

Accepted Answer

Enable high availability (HA) on the AlloyDB cluster, which provisions a standby in a different zone.. AlloyDB provides automatic failover within 30 seconds when you enable high availability (primary + standby). This is zone-redundant within the same region.

Answer

Configure a cross-region read replica and promote it manually during a disaster.

Answer

Deploy AlloyDB in a single zone without HA.

Answer

Use AlloyDB with multiple read pools and a custom failover script.

Question 6

A company uses Cloud SQL for MySQL with a 1-hour RPO and 2-hour RTO. They currently rely on automated daily backups. To improve DR capabilities, they want to reduce RPO to 5 minutes while keeping costs low. Which action should they take?

Accepted Answer

Enable point-in-time recovery (PITR) with a binary log retention of 5 minutes.. Enabling point-in-time recovery (PITR) on Cloud SQL allows restoring to any point in time within the backup retention period, reducing RPO from 24 hours to seconds (limited to binary log retention).

Answer

Increase backup frequency to every hour.

Answer

Create a cross-region read replica.

Answer

Deploy Cloud SQL HA with a standby in another zone.

Question 7

What is the maximum backup retention period for Cloud Spanner backups?

Accepted Answer

365 days. Cloud Spanner allows backups to be retained for up to 365 days.

Answer

730 days

Answer

90 days

Answer

30 days

Question 8

A company runs an e-commerce platform on Cloud Spanner multi-region (nam6). They experience a regional failure affecting the leader region. After failover, they observe increased write latency. What is the most likely cause?

Accepted Answer

The new leader region is geographically farther from the application instances.. In a multi-region Spanner configuration, the leader region handles write coordination. After failover, a new leader is elected in a different region, which may be farther from the majority of clients, increasing write latency if clients are not geographically distributed.

Answer

The new leader region has fewer replicas.

Answer

The instance is now running in read-only mode.

Answer

The failover caused data loss, requiring recovery.

Question 9

A company uses Cloud Bigtable with replication across two regions. They want to implement a DR plan that minimizes RPO and RTO. Which TWO steps should they take? (Choose 2)

Accepted Answer

Configure multi-cluster routing with read-failover.. Using multi-cluster routing with read-failover ensures reads automatically switch to the secondary cluster when primary is unhealthy, minimizing RPO by directing writes to primary. Regularly testing failover validates the process and updates runbooks.

Answer

Enable automatic failover for writes in the Bigtable cluster configuration.

Answer

Set the replication routing policy to any-replica.

Answer

Set the replication routing policy to single-cluster with failover priority.

Question 10

An organization needs to design a disaster recovery plan for Cloud SQL for PostgreSQL with an RPO of 10 seconds and an RTO of 5 minutes. Which TWO solutions meet these requirements? (Choose 2)

Accepted Answer

Cloud SQL cross-region read replica with manual promotion.. Cloud SQL HA provides near-zero RPO and RTO under 60 seconds within the same region. Cross-region read replicas can achieve RPO of seconds if replication lag is low, and manual promotion takes minutes.

Answer

Export the database to Cloud Storage and import in another region.

Answer

Cloud SQL point-in-time recovery from backups.

Answer

Use Cloud SQL automated backups with cross-region copy.

Question 11

A company runs a global application on Cloud Spanner with a multi-region configuration. They need to test their DR procedures without impacting production. Which THREE actions should they perform? (Choose 3)

Accepted Answer

Simulate a zone failure by modifying IAM permissions to restrict access to replicas in a zone.. Non-destructive tests include creating a backup and restoring it to a separate instance for validation, simulating a zone failure by restricting replica access, and performing regular failover drills via backup/restore to test RTO.

Answer

Delete the production instance and recreate it from a backup.

Answer

Promote a read replica to a writable instance in a different region.

Question 12

A company uses Cloud SQL for MySQL and wants to define backup retention policies for compliance. Which TWO statements about Cloud SQL backup retention are correct? (Choose 2)

Accepted Answer

The maximum retention period for automated backups is 365 days.. Cloud SQL supports up to 365 automated backups and allows setting retention days up to 365. Point-in-time recovery also has a configurable retention.

Answer

Point-in-time recovery logs are retained for a maximum of 7 days.

Answer

Automated backups are retained for a minimum of 7 days.

Answer

Backups are always stored in the same region as the database.

Question 13

A company is planning disaster recovery for Bigtable. They have two clusters in different regions with replication enabled. They want to automate failover using Cloud DNS. Which THREE components are required for this automation? (Choose 3)

Accepted Answer

Cloud HTTP(S) health check for the Bigtable cluster endpoints.. To automate Bigtable failover, you need a Cloud HTTP(S) health check to monitor the primary cluster, a Cloud DNS routing policy (e.g., weighted round robin) that can be updated, and a mechanism (e.g., Cloud Functions or an external tool) to update the DNS record when the health check fails.

Answer

Bigtable replication routing policy set to any-replica.

Answer

Cloud Bigtable AppProfile with single-cluster routing.

Question 14

A company runs a critical application on AlloyDB in a single zone. They want to improve resiliency with an RTO under 30 seconds and RPO near zero. Which THREE steps should they take? (Choose 3)

Accepted Answer

Configure application connection retry logic to handle failover interruptions.. To achieve RTO<30s and RPO near zero, you need to enable AlloyDB HA (primary + standby in different zone), ensure the application retries connections during failover, and regularly test failover to validate RTO.

Answer

Increase the number of CPU cores in the primary instance.

Answer

Configure a cross-region read replica in a different region.

Question 15

A company uses Cloud Spanner and needs to design a backup strategy that meets a 24-hour RPO and 4-hour RTO. Which TWO statements are correct for achieving these goals? (Choose 2)

Accepted Answer

Schedule a daily backup of the Spanner database.. Spanner backups can be created on-demand or scheduled. The backup restore typically completes in hours depending on size, and can meet 4-hour RTO. Scheduling daily backups meets 24-hour RPO.

Answer

Use point-in-time recovery to restore to any point within the last 24 hours.

Answer

Export the database to Avro files in Cloud Storage.

Answer

Create a cross-region read replica for failover.