PCDE Deploy scalable and highly available databases in Google Cloud Practice Test 4 — 15 Questions

Question 1

A company is evaluating disaster recovery options for their production Bigtable instance. They need asynchronous replication with manual failover and the ability to route reads to the secondary cluster only when the primary is unhealthy. Which TWO settings should they configure? (Choose 2 correct answers.)

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

Accepted Answer

Use Cloud DNS health checks to update DNS records to point to the secondary cluster. Bigtable replication supports asynchronous replication with app profiles. To achieve manual failover with read routing to the secondary cluster only when the primary is unhealthy, two configurations are needed: (1) A read-failover routing policy on an app profile directs reads to the secondary during a failover event, and (2) Cloud DNS health checks update DNS records to point to the secondary cluster, enabling manual failover control. Option B is incorrect because synchronous replication would require automatic failover, not manual. Option C is incorrect because multi-cluster routing with single-cluster fallback does not meet the primary-unhealthy-only requirement. Option E is incorrect because any-replica routing would send reads to the secondary during normal operation, not just when primary is unhealthy.

Answer

Enable automatic failover by setting the replication to synchronous mode

Answer

Configure a multi-cluster routing policy with a single-cluster fallback

Answer

Create an app profile with any-replica routing policy

Question 2

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

Firestore

Answer

Cloud Spanner

Answer

BigQuery

Question 3

A financial application requires zero data loss (RPO=0) and automatic failover within 60 seconds in the event of a zone failure. The database must support ACID transactions. Which Google Cloud service meets these requirements?

Accepted Answer

Cloud SQL with HA configuration. Cloud SQL with HA configuration uses synchronous replication to a standby instance in a different zone. If the primary zone fails, Cloud SQL automatically fails over to the standby. Because replication is synchronous, RPO is effectively zero. Automatic failover typically completes within 60 seconds.

Answer

Cloud SQL cross-region read replica

Answer

Cloud SQL single-zone instance with automatic backups

Answer

Cloud Bigtable multi-cluster replication

Question 4

A global e-commerce platform uses Cloud Spanner multi-region configuration. The compliance team mandates that all write transactions must be committed in a specific geographic region to comply with data sovereignty laws. Which Spanner feature should be used to enforce this requirement?

Accepted Answer

Set the default leader region to the required region. Spanner's leader region configuration allows you to designate a specific region where all write transactions are coordinated. This ensures that the commit timestamp and transaction processing occur within that region, helping meet data sovereignty requirements.

Answer

Enable customer-managed encryption keys (CMEK)

Answer

Use read-only replicas in the required region

Answer

Deploy a regional instance in the required region

Question 5

An organization uses Cloud SQL for MySQL and needs to perform disaster recovery testing by failing over to a cross-region read replica without impacting the primary instance. They want to validate the promotion process and measure the actual RTO. Which approach should be used?

Accepted Answer

Promote a cross-region read replica in an isolated project or non-production environment. The safest way to test DR without impacting the primary is to promote a cross-region read replica in a non-production environment or an isolated project. The promotion is manual and can be tested by simulating a failover scenario. Alternatively, you can clone the replica to a separate instance for testing, but the most direct test is promoting a replica that is not serving production traffic.

Answer

Create a clone of the primary instance in the target region and test failover

Answer

Use Cloud SQL’s switchover feature for HA instances

Answer

Run a gcloud command to promote the existing read replica in the production project

Question 6

A gaming company uses Cloud Bigtable for player state data with two clusters in different regions (us-central1 and us-west1) for disaster recovery. They need to ensure that read traffic automatically fails over to the secondary cluster if the primary cluster becomes unhealthy. They currently have a weighted DNS routing policy. Which additional configuration is required?

Accepted Answer

Set the Bigtable cluster routing policy to 'read-failover'. Cloud Bigtable with multi-cluster replication can use routing policies. The 'read-failover' routing policy directs reads to the nearest healthy cluster. To handle unhealthy clusters, you can use Cloud DNS with a health check that updates the routing policy, but the simplest approach is to configure the Bigtable routing policy to 'read-failover'. This policy automatically shifts reads away from unhealthy clusters.

Answer

Use a Cloud DNS health check that updates a routing policy in Bigtable

Answer

Enable multi-cluster routing by setting 'any-replica' policy

Answer

Configure a Cloud Load Balancer with a backend service pointing to the Bigtable clusters

Question 7

A company runs a critical application on AlloyDB with a primary instance and a read pool. They want to achieve the fastest possible automatic failover during a zone outage, with minimal data loss. What is the expected RTO and RPO for AlloyDB's automatic failover within the same region?

Accepted Answer

RTO < 30 seconds, RPO ~ 0. AlloyDB provides automatic failover to a standby node within the same region, typically completing in under 30 seconds. Replication is synchronous within the region, so RPO is zero (no data loss).

Answer

RTO < 5 minutes, RPO ~ 1 second

Answer

RTO < 60 seconds, RPO ~ 0

Answer

RTO < 30 seconds, RPO < 1 minute

Question 8

A healthcare company uses Cloud SQL for PostgreSQL and needs to meet a disaster recovery requirement of RPO = 1 hour and RTO = 2 hours for a cross-region failover. They currently have a cross-region read replica in another region. Which additional action should they take to meet the RPO consistently?

Accepted Answer

Set up monitoring and alerting on the replication lag metric. Cross-region read replicas have asynchronous replication lag, which can vary. To ensure that the RPO is bounded to 1 hour, the company must monitor the replication lag and alert if it exceeds 1 hour. They can also increase the replica's resources to reduce lag, but monitoring is essential to guarantee the RPO.

Answer

Configure the read replica to use synchronous replication

Answer

Increase the replica's storage capacity

Answer

Enable point-in-time recovery on the primary instance

Question 9

A financial services firm runs a multi-region Spanner instance with the nam-eur-asia1 configuration. They need to ensure that if the leader region (us-central1) becomes unavailable, failover to another region occurs automatically within 1 minute. What is the expected RPO and RTO for this scenario?

Accepted Answer

RPO ~ 15 seconds, RTO < 1 minute. Spanner multi-region configurations provide automatic failover with RTO under 1 minute. For the nam-eur-asia1 configuration, it is a multi-region with multiple read-write replicas. The RPO is approximately 15 seconds because Spanner uses quorum-based replication; in the event of a region failure, a small number of recent transactions may be uncommitted.

Answer

RPO ~ 0, RTO ~ 15 seconds

Answer

RPO ~ 1 hour, RTO ~ 5 minutes

Answer

RPO = 0, RTO < 1 minute

Question 10

A media streaming company uses Cloud Bigtable to store user session data with a single cluster in us-east1. They want to add disaster recovery capability with an RPO of no more than 5 minutes and an RTO of under 10 minutes. Which action should they take?

Accepted Answer

Add a second cluster in a different region with replication, and configure a Cloud DNS health check to redirect traffic. Bigtable replication allows adding a second cluster in a different region with asynchronous replication. The replication lag can be within seconds, typically under 5 minutes. For RTO under 10 minutes, manual failover via the Cloud Console or CLI is sufficient; automatic failover is not built-in but can be achieved with external orchestration.

Answer

Use Cloud SQL cross-region read replicas

Answer

Deploy a new Bigtable instance in another region and set up dataflow pipelines to replicate data

Answer

Create an on-demand backup and restore to another region

Question 11

A company runs an e-commerce platform on Cloud SQL for MySQL. They need to comply with a policy that requires database backups to be retained for 365 days. They also need to restore to any point within the last 30 days. How should they configure their backup settings?

Accepted Answer

Enable automated backups with retention set to 30 days and create on-demand backups daily to cover the 365-day retention. Cloud SQL supports automated backups and point-in-time recovery (PITR) using binary logs. The maximum automated backup count is 365, and you can set the transaction log retention for PITR up to 35 days. For 365-day retention, you need to use on-demand backups (snapshots) which can be retained indefinitely. For PITR within 30 days, enable automated backups and binary logging with a log retention of 30 days.

Answer

Use export to Cloud Storage daily and store exports for 365 days

Answer

Enable automated backups with retention set to 365 days and enable binary logging for PITR

Answer

Enable automated backups with retention set to 365 days and set transaction log retention to 365 days

Question 12

A company uses Cloud Spanner and needs to retain backups for 365 days for compliance. What is the maximum backup expiration period that can be set for a Spanner backup?

Accepted Answer

365 days. Spanner backups can have an expiration time set to a maximum of 365 days from the creation time. After that, the backup is automatically deleted.

Answer

30 days

Answer

Unlimited

Answer

90 days

Question 13

A DevOps team is implementing chaos engineering for their Cloud SQL for PostgreSQL database. They want to simulate a zone failure that triggers automatic failover of their HA instance without causing data loss. Which approach should they use?

Accepted Answer

Use the gcloud sql instances failover command. Cloud SQL HA instances have automatic zone failover. To simulate a zone failure, you can use the gcloud command to trigger failover manually. This performs a planned failover that switches to the standby zone without data loss, mimicking a zone outage.

Answer

Stop the Cloud SQL instance using gcloud sql instances patch --activation-policy NEVER

Answer

Restrict network access to the primary instance

Answer

Delete the primary database

Question 14

A company is designing a disaster recovery strategy for their Cloud Spanner database. They need an RPO of less than 30 seconds and an RTO of less than 1 minute. Which two configurations would meet these requirements? (Choose TWO)

Accepted Answer

Multi-region configuration with read-write replicas (e.g., nam3). The correct answers are B and D. A multi-region configuration with read-write replicas (e.g., nam3) provides automatic failover across regions with an RPO of approximately 15 seconds and an RTO of less than 1 minute, meeting the requirements for region-level failures. A regional instance in Cloud Spanner provides synchronous replication within the region, achieving an RPO of zero and an RTO of seconds, which meets the requirements for zone-level failures within a region. Option A (cross-region backup and restore) typically has an RPO of hours and RTO of hours, so it does not meet the strict RPO/RTO. Option C (point-in-time recovery) provides RPO of seconds to minutes but depends on backups and may not achieve RTO <1 minute for restore operations. Option E (multi-region with read-only replicas) does not support automatic failover because read-only replicas cannot become the new leader, so failover is not automatic and RTO would be longer.

Answer

Cross-region backup and restore

Answer

Point-in-time recovery (PITR)

Answer

Multi-region configuration with read-only replicas

Question 15

A company uses Cloud Bigtable with two clusters in different regions for disaster recovery. They need to ensure that if the primary cluster becomes unavailable, read traffic is automatically redirected to the secondary cluster with minimal manual intervention. Which three actions should they take? (Choose THREE)

Accepted Answer

Enable multi-cluster replication between the clusters. To achieve automatic failover for Bigtable reads, you need: (1) multi-cluster replication enabled, (2) a routing policy that supports failover (read-failover or any-replica with health checking), and (3) an external health check mechanism (like Cloud DNS health checks) to redirect client traffic if the primary cluster is unhealthy. Option D (write failback) is not relevant for reads. Option E (read-only replicas) is not applicable as Bigtable doesn't have that concept.

Answer

Add read-only replicas to the secondary cluster

Answer

Configure a write failback policy to switch write clusters