Manage a solution that can span multiple database technologies →mediumMultiple SelectObjective-mapped
PCDE Practice Question: Manage a solution that can span multiple database technologies
A company is using Cloud SQL for PostgreSQL and needs to perform a disaster recovery drill by promoting a read replica to a standalone instance. They also need to ensure the replica is as current as possible before promotion. Which TWO steps should they take? (Choose two.)
⚠ Common exam trap
Watch out — candidates often confuse promoting a read replica with performing a failover in a Cloud SQL high-availability cluster, leading them to select 'Force a failover to the replica' instead of the correct promotion command using 'gcloud sql instances promote-replica'.
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
✓
Promote the replica using gcloud sql instances promote-replica
`gcloud sql instances promote-replica` is the standard command to promote a Cloud SQL read replica to a standalone instance, making it a primary that can accept writes. Option C is correct because checking the `replication_lag` metric ensures the replica has applied all pending changes from the primary before promotion, minimizing data loss. This step is critical because promoting a replica that is behind can result in lost transactions.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Promote the replica using gcloud sql instances promote-replica
Why this is correct
Promotion converts the read replica into a standalone instance.
- ✗
Enable binary logging on the replica
Why it's wrong here
Binary logging is for MySQL, not PostgreSQL.
- ✓
Check the replication_lag metric on the replica to confirm it is within acceptable range
Why this is correct
Replication lag should be minimal to avoid data loss during promotion.
- ✗
Create an on-demand backup of the primary before promotion
Why it's wrong here
Not necessary; the replica already has data from the primary.
- ✗
Force a failover to the replica
Why it's wrong here
Failover is for HA configurations, not for read replicas.
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Same concept, more angles
8 more ways this is tested on PCDE
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company has a Cloud SQL for PostgreSQL instance with a read replica in another region. They want to perform disaster recovery testing without affecting the primary. What should they do?
medium- ✓ A.Promote the read replica to a standalone instance and use it for testing.
- B.Use the replica as a failover target; testing is not allowed.
- C.Enable point-in-time recovery on the replica and restore to a new instance.
- D.Create a clone of the primary instance and test on that.
Why A: Promoting the read replica to a standalone instance detaches it from the primary, creating an independent writable Cloud SQL instance. This allows you to perform disaster recovery testing (e.g., failover validation, data integrity checks) without any impact on the primary instance, as the replica no longer replicates changes from the primary.
Variation 2. An organization needs to run a disaster recovery drill for its Cloud SQL for MySQL instance by promoting a read replica to a standalone instance. The replica is in the same region as the primary. After the drill, they want the original primary to resume serving writes. What should they do?
easy- ✓ A.Promote the replica, then delete and recreate the replica from the original primary after the drill.
- B.Stop replication, then restart the primary instance to make it the new replica.
- C.Use the gcloud command to switch roles between the primary and replica.
- D.Promote the replica, then perform a failover on the original primary to make it the new primary.
Why A: Promoting a read replica in Cloud SQL for MySQL breaks the replication link, making the replica a standalone primary. After the drill, you must delete the promoted replica and create a new read replica from the original primary to re-establish replication. This is the only supported method because Cloud SQL does not allow reversing the promotion or re-attaching a promoted instance as a replica.
Variation 3. A company has a Cloud SQL for MySQL instance with a cross-region read replica for disaster recovery. During a regional outage, they need to promote the read replica to a standalone instance as quickly as possible. What is the correct procedure?
medium- A.Create a backup of the replica and restore it as a new instance
- B.Delete the read replica and restore a backup from the primary as a new instance
- ✓ C.Use the gcloud sql instances promote-replica command on the replica
- D.Stop replication on the replica by issuing STOP SLAVE on the instance
Why C: Promoting a read replica makes it a standalone instance. It can be done via the Cloud Console or gcloud command. The promotion is immediate, but the original primary may still be active if not stopped.
Variation 4. A company is using Cloud SQL for MySQL and wants to perform disaster recovery testing by promoting a read replica to a standalone instance. Which TWO actions are required? (Choose 2)
medium- ✓ A.Stop replication on the replica using the Cloud Console or gcloud.
- B.Delete the replica and recreate it as a primary instance.
- C.Enable point-in-time recovery on the replica.
- D.Disable binary logging on the replica.
- ✓ E.Promote the replica using the 'promote' action in Cloud Console or gcloud.
Why A: To promote a read replica to a standalone instance, you must stop replication on the replica and then promote it. The promotion process converts the replica into an independent primary instance.
Variation 5. 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?
medium- ✓ A.Promote a cross-region read replica to a standalone instance in the same project and test connectivity.
- B.Create a clone of the primary instance in another region and test failover to the clone.
- C.Use the gcloud sql instances failover command on the primary instance.
- D.Stop the primary instance and promote the read replica, then later re-promote the original primary.
Why A: 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.
Variation 6. A company runs a critical application on Cloud SQL for MySQL with an HA configuration. They want to test their disaster recovery plan without affecting production. They need to validate that a cross-region read replica can be promoted successfully in the event of a regional outage. Which approach should they take?
hard- A.Promote the cross-region read replica to a standalone instance, then re-create the replica after testing
- B.Use point-in-time recovery to restore the primary to a new instance in the secondary region
- C.Create a new read replica in the secondary region and promote that
- ✓ D.Create a clone of the cross-region read replica and promote the clone
Why D: To test DR without affecting production, you can promote a cross-region read replica to a standalone instance for testing. However, promoting a read replica stops replication and makes it a writable instance. To avoid impacting production, you should create a clone of the cross-region read replica and promote the clone. Alternatively, you can create a snapshot of the replica and restore to a new instance. The safest way is to create a clone from the replica and promote the clone.
Variation 7. 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?
medium- A.Create a clone of the primary instance in the target region and test failover
- B.Use Cloud SQL’s switchover feature for HA instances
- ✓ C.Promote a cross-region read replica in an isolated project or non-production environment
- D.Run a gcloud command to promote the existing read replica in the production project
Why C: 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.
Variation 8. 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?
medium- A.Create a clone of the primary instance and promote the clone to simulate failover.
- ✓ B.Promote the cross-region read replica to a standalone instance in a separate project for testing.
- C.Trigger a failover using the gcloud sql instances failover command on the primary instance.
- D.Stop the primary instance and observe how the application behaves.
Why B: 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.
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.