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PCDE Practice Question: Deploy scalable and highly available databases in Google Cloud
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.)
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
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 analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Use Cloud DNS health checks to update DNS records to point to the secondary cluster
Why this is correct
During manual failover, updating DNS records to point to the secondary is necessary, and health checks can automate this.
- ✗
Enable automatic failover by setting the replication to synchronous mode
Why it's wrong here
Bigtable replication is asynchronous; synchronous mode is not available.
- ✗
Configure a multi-cluster routing policy with a single-cluster fallback
Why it's wrong here
This is not a standard Bigtable routing policy.
- ✓
Create an app profile with read-failover routing policy
Why this is correct
read-failover sends read requests to the secondary only when the primary is unhealthy, meeting the requirement.
- ✗
Create an app profile with any-replica routing policy
Why it's wrong here
any-replica routes to the nearest cluster regardless of health, so reads may go to secondary even when primary is healthy.
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Variation 1. 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?
medium- A.Use single-cluster routing with failover priority set to the secondary cluster.
- B.Use any-replica routing and let Cloud Bigtable automatically direct reads and writes to the healthiest cluster.
- C.Use single-cluster routing and regularly back up the Bigtable data.
- ✓ D.Use multi-cluster routing with read-failover enabled and direct all writes to the primary cluster.
Why D: 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.
Variation 2. 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?
hard- A.Use a Cloud DNS health check that updates a routing policy in Bigtable
- ✓ B.Set the Bigtable cluster routing policy to 'read-failover'
- C.Enable multi-cluster routing by setting 'any-replica' policy
- D.Configure a Cloud Load Balancer with a backend service pointing to the Bigtable clusters
Why B: 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.
Variation 3. A company is designing a disaster recovery plan for their Cloud Bigtable instance. They need to ensure that in the event of a regional outage, they can failover to a secondary region with minimal data loss and automatic re-routing of traffic. Which TWO actions should they take? (Choose two.)
medium- A.Export Bigtable data to Cloud Storage daily and script the import into a new cluster.
- ✓ B.Set up Cloud DNS with a health check that updates the routing policy to the secondary cluster on failure.
- C.Increase the number of nodes in the primary cluster to handle failover load.
- ✓ D.Configure Bigtable replication with a secondary cluster in a different region.
- E.Use Cloud Spanner instead of Bigtable for built-in multi-region failover.
Why B: 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.
Variation 4. A company uses Cloud Bigtable for their analytics pipeline. They set up replication with a primary cluster in us-central1 and a secondary in us-west1. They notice that during normal operation, queries always hit the primary cluster even if the secondary is closer. What should they change to route queries to the nearest cluster automatically?
hard- ✓ A.Change the app profile routing policy to any-replica
- B.Implement client-side logic to choose which cluster to query
- C.Modify the primary cluster to be in us-west1
- D.Update the app profile to use read-failover routing
Why A: The default routing policy for Bigtable replication is single-cluster (to the primary). To route to the nearest healthy cluster, they need to enable the any-replica routing policy in their Bigtable app profile. read-failover is for DR failover, not for normal operations. Changing the primary cluster does not solve the routing issue. Client-side logic is an option but not a built-in solution.
Variation 5. 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)
medium- ✓ A.Configure multi-cluster routing with read-failover.
- ✓ B.Regularly perform failover drills using Cloud DNS health checks to update routing.
- C.Enable automatic failover for writes in the Bigtable cluster configuration.
- D.Set the replication routing policy to any-replica.
- E.Set the replication routing policy to single-cluster with failover priority.
Why A: 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.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCDE practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCDE exam.