The answer is cross-region replication using external replicas. This is correct because Cloud SQL for MySQL lacks native cross-region replication support, so you must configure an external replica—typically a MySQL instance on Compute Engine in a different region—that uses MySQL’s native binary log (binlog) replication to continuously apply changes from the primary Cloud SQL instance. On the Google Professional Cloud Database Engineer exam, this scenario tests your understanding of Cloud SQL’s architectural limitations and your ability to design hybrid disaster recovery solutions using external replicas. A common trap is assuming Cloud SQL’s built-in replicas support cross-region failover, but those are limited to the same region; the key distinction is that external replicas leverage standard MySQL replication outside the managed service. Memory tip: “External for cross-region, internal for same-region”—if the disaster recovery target is in a different region, think external replica.
PCDE Plan and manage database infrastructure Practice Question
This PCDE practice question tests your understanding of plan and manage database infrastructure. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company needs a cross-region disaster recovery solution for their Cloud SQL MySQL database. Which feature should they use?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Cross-region replication using external replicas.
Option C is correct because Cloud SQL for MySQL does not natively support cross-region replication, but you can achieve it by configuring an external replica (a MySQL instance running outside Cloud SQL, such as on Compute Engine) that uses MySQL's native binary log (binlog) replication from the primary Cloud SQL instance. This setup allows you to maintain a standby database in a different region for disaster recovery, with the external replica continuously applying changes from the primary.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Read replicas in the same region.
Why it's wrong here
Same-region replicas do not provide cross-region disaster recovery.
✗
Cloud SQL for MySQL does not support cross-region replication.
Why it's wrong here
This is incorrect; cross-region replication is supported via external replicas.
✓
Cross-region replication using external replicas.
Why this is correct
An external replica in a different region can serve as a disaster recovery target.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use Database Migration Service to continuously copy data.
Why it's wrong here
Database Migration Service is for one-time migrations, not ongoing replication.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume Cloud SQL for MySQL has a built-in cross-region replica feature like Cloud SQL for PostgreSQL or Spanner, but it does not, leading them to incorrectly select Option B or D.
Detailed technical explanation
How to think about this question
The external replica approach relies on MySQL's asynchronous binlog replication: the primary Cloud SQL instance streams binary log events to the external replica, which replays them. You must configure the external replica with the correct server ID, enable GTID-based replication for consistency, and ensure network connectivity (e.g., via Cloud VPN or Private Service Connect) to avoid data exposure. A real-world scenario is a financial application requiring a cross-region standby to meet RPO of seconds, where the external replica can be promoted to a standalone Cloud SQL instance during a regional failure.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Plan and manage database infrastructure — This question tests Plan and manage database infrastructure — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Cross-region replication using external replicas. — Option C is correct because Cloud SQL for MySQL does not natively support cross-region replication, but you can achieve it by configuring an external replica (a MySQL instance running outside Cloud SQL, such as on Compute Engine) that uses MySQL's native binary log (binlog) replication from the primary Cloud SQL instance. This setup allows you to maintain a standby database in a different region for disaster recovery, with the external replica continuously applying changes from the primary.
What should I do if I get this PCDE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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