- A
Cloud SQL with cross-region replicas
Why wrong: Cloud SQL replicas are read-only, not for global writes. No 99.999% SLA.
- B
Firestore
Why wrong: Eventual consistency across regions; no 99.999% SLA.
- C
Cloud Bigtable
Why wrong: Eventually consistent; no global consistency.
- D
Cloud Spanner
Correct: global distribution, strong consistency, 99.999% SLA.
Question 126 of 1,000
PDE Storing the Data Practice Question
This PDE practice question tests your understanding of storing the data. 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.
An application requires a globally distributed, strongly consistent database with 99.999% availability SLA. The workload is OLTP with high throughput across continents. Which service fits best?
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
✓
Cloud Spanner
Cloud Spanner is the only service that provides globally distributed, strongly consistent (external consistency via TrueTime) OLTP with 99.999% availability SLA. It supports high-throughput ACID transactions across continents using synchronous replication and atomic clocks, meeting all stated requirements.
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.
- ✗
Cloud SQL with cross-region replicas
Why it's wrong here
Cloud SQL replicas are read-only, not for global writes. No 99.999% SLA.
- ✗
Firestore
Why it's wrong here
Eventual consistency across regions; no 99.999% SLA.
- ✗
Cloud Bigtable
Why it's wrong here
Eventually consistent; no global consistency.
- ✓
Cloud Spanner
Why this is correct
Correct: global distribution, strong consistency, 99.999% SLA.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that cross-region replicas in Cloud SQL provide strong consistency, but candidates must remember that asynchronous replication leads to eventual consistency and a lower SLA.
Detailed technical explanation
How to think about this question
Cloud Spanner achieves global strong consistency using TrueTime, which synchronizes clocks across Google's data centers via GPS and atomic clocks, enabling external consistency for distributed transactions. It uses Paxos-based synchronous replication across zones and regions, ensuring that all reads and writes are globally ordered without sacrificing availability. In real-world scenarios like financial trading or inventory management across continents, Spanner's ability to maintain ACID properties with 99.999% availability is critical, whereas other databases would introduce stale reads or write conflicts.
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.
- →
Storing the Data — study guide chapter
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FAQ
Questions learners often ask
What does this PDE question test?
Storing the Data — This question tests Storing the Data — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Cloud Spanner — Cloud Spanner is the only service that provides globally distributed, strongly consistent (external consistency via TrueTime) OLTP with 99.999% availability SLA. It supports high-throughput ACID transactions across continents using synchronous replication and atomic clocks, meeting all stated requirements.
What should I do if I get this PDE 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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Last reviewed: Jul 4, 2026
This PDE 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 PDE exam.
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