PCDE Practice Question: Deploy scalable and highly available databases in Google Cloud
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?
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 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 analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Stop the Cloud SQL instance using gcloud sql instances patch --activation-policy NEVER
Why it's wrong here
This stops the instance, but does not test HA failover; it will not automatically failover to standby.
- ✓
Use the gcloud sql instances failover command
Why this is correct
The 'gcloud sql instances failover' command triggers a graceful failover to the standby zone, simulating a zone failure without data loss.
- ✗
Restrict network access to the primary instance
Why it's wrong here
This would not trigger automatic HA failover; the instance remains online but unreachable.
- ✗
Delete the primary database
Why it's wrong here
This would cause data loss and is not a proper test.
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Same concept, more angles
3 more ways this is tested on PCDE
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Variation 1. 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?
easy- ✓ A.Cloud SQL with HA configuration
- B.Cloud SQL cross-region read replica
- C.Cloud SQL single-zone instance with automatic backups
- D.Cloud Bigtable multi-cluster replication
Why A: 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.
Variation 2. 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?
easy- A.RTO < 5 minutes, RPO ~ 1 second
- B.RTO < 60 seconds, RPO ~ 0
- C.RTO < 30 seconds, RPO < 1 minute
- ✓ D.RTO < 30 seconds, RPO ~ 0
Why D: 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).
Variation 3. 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?
medium- A.Cloud Firestore in multi-region mode
- B.Cloud Bigtable with multi-cluster routing and replication
- C.Cloud SQL with cross-region read replica
- ✓ D.Cloud Spanner multi-region configuration
Why D: 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.
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.