- A
The new primary is in a different region, causing higher network round-trip times for applications that are still in us-central1.
After failover, the primary is in us-east1, while application instances in us-central1 incur cross-region latency for each write.
- B
Cross-region replication triggers a mandatory 1-hour delay before writes are allowed.
Why wrong: There is no such mandatory delay; writes are allowed after failover promotion.
- C
The failover did not complete successfully; the replica is still in read-only mode.
Why wrong: If failover completed, the replica should be writable. Cloud SQL failover promotes the replica to primary.
- D
The replica had a replication lag of 5 minutes, causing data inconsistency.
Why wrong: Replication lag could exist but does not directly cause high write latency on the new primary.
Quick Answer
The answer is that the new primary is in a different region, causing higher network round-trip times for applications still in us-central1. This is correct because after a cross-region failover, the Cloud SQL for MySQL instance moves to us-east1, but the application compute resources remain in us-central1, forcing every write to traverse the wide-area network between regions, which introduces significant latency. On the Google Professional Cloud Database Engineer exam, this scenario tests your understanding that Cloud SQL failover does not automatically relocate application resources, so a cross-region failover directly impacts write latency due to geographic distance. A common trap is assuming that failover alone resolves performance issues, but in reality, you must also migrate or reconfigure application endpoints to the new region. Memory tip: think “failover moves the database, not the app”—always plan for application relocation after a cross-region failover to avoid high latency.
PCDE Plan and manage database infrastructure Practice Question
This PCDE practice question tests your understanding of plan and manage database infrastructure. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 uses Cloud SQL for MySQL with a failover replica. The primary instance is in us-central1 and the replica is in us-east1. During a regional outage in us-central1, the database engineer executes an emergency failover to the replica. After the failover, applications experience high latency when writing to the new primary. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Clue:
"primary"Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
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
The new primary is in a different region, causing higher network round-trip times for applications that are still in us-central1.
Option A is correct because after a cross-region failover, the new primary resides in us-east1 while the applications remain in us-central1. This geographic distance increases network round-trip time (RTT) for write operations, as each write must traverse the WAN between regions. Cloud SQL for MySQL does not automatically relocate compute resources, so latency-sensitive applications will experience higher write latency until they are migrated or configured to connect to the new region.
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.
- ✓
The new primary is in a different region, causing higher network round-trip times for applications that are still in us-central1.
Why this is correct
After failover, the primary is in us-east1, while application instances in us-central1 incur cross-region latency for each write.
Clue confirmation
The clue words "most likely", "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Cross-region replication triggers a mandatory 1-hour delay before writes are allowed.
Why it's wrong here
There is no such mandatory delay; writes are allowed after failover promotion.
- ✗
The failover did not complete successfully; the replica is still in read-only mode.
Why it's wrong here
If failover completed, the replica should be writable. Cloud SQL failover promotes the replica to primary.
- ✗
The replica had a replication lag of 5 minutes, causing data inconsistency.
Why it's wrong here
Replication lag could exist but does not directly cause high write latency on the new primary.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that failover automatically fixes all performance issues, but the trap here is that candidates overlook the impact of geographic latency on write operations after a cross-region failover, focusing instead on replication lag or read-only mode.
Detailed technical explanation
How to think about this question
Cross-region failover in Cloud SQL for MySQL uses asynchronous replication by default, meaning the replica may be slightly behind the primary. After promotion, the new primary accepts writes immediately, but applications still in the original region must send data over the public internet or a Cloud VPN, adding 30-100 ms of latency per round trip. This latency is compounded by TCP slow start and TLS handshake overhead, making write-heavy workloads particularly sensitive to geographic distance.
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 — study guide chapter
Learn the concepts, then practise the questions
- →
Plan and manage database infrastructure practice questions
Targeted practice on this topic area only
- →
All PCDE questions
503 questions across all exam domains
- →
Google Professional Cloud Database Engineer study guide
Full concept coverage aligned to exam objectives
- →
PCDE practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related PCDE practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Plan and manage database infrastructure practice questions
Practise PCDE questions linked to Plan and manage database infrastructure.
Define data structures and implement SQL for Business Intelligence practice questions
Practise PCDE questions linked to Define data structures and implement SQL for Business Intelligence.
Design and implement database schemas practice questions
Practise PCDE questions linked to Design and implement database schemas.
Monitor and optimize database performance practice questions
Practise PCDE questions linked to Monitor and optimize database performance.
PCDE fundamentals practice questions
Practise PCDE questions linked to PCDE fundamentals.
PCDE scenario practice questions
Practise PCDE questions linked to PCDE scenario.
PCDE troubleshooting practice questions
Practise PCDE questions linked to PCDE troubleshooting.
Practice this exam
Start a free PCDE practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this PCDE question test?
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: The new primary is in a different region, causing higher network round-trip times for applications that are still in us-central1. — Option A is correct because after a cross-region failover, the new primary resides in us-east1 while the applications remain in us-central1. This geographic distance increases network round-trip time (RTT) for write operations, as each write must traverse the WAN between regions. Cloud SQL for MySQL does not automatically relocate compute resources, so latency-sensitive applications will experience higher write latency until they are migrated or configured to connect to the new region.
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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely", "primary". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Keep practising
More PCDE practice questions
- A company stores sensor data in BigQuery. They have a table 'sensor_readings' with columns: sensor_id, reading_time, val…
- Which THREE are valid considerations when designing BigQuery tables for BI reporting?
- A team is migrating an on-premises PostgreSQL database to Cloud SQL for PostgreSQL. The existing schema uses a large num…
- A company is designing a Cloud Firestore schema for a social media application. Users can follow other users, and the ap…
- Match each Cloud SQL tier to its description.
- A financial services company uses Cloud Spanner for a global transaction processing system. They notice that certain rea…
Last reviewed: Jun 30, 2026
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.