- A
Use a global HTTP(S) load balancer with a single global MIG and a multi-region Cloud Spanner instance.
Why wrong: There is no global MIG; MIGs are per region.
- B
Use a global HTTP(S) load balancer with a single zonal MIG and Cloud Spanner single-region.
Why wrong: A single zonal MIG can't tolerate zone failure; single-region Spanner can't survive region failure.
- C
Use a global HTTP(S) load balancer with regional MIGs in multiple regions, each spanning zones, and a multi-region Cloud Spanner instance.
Regional MIGs across zones handle zone failures; multiple regions and multi-region Spanner handle region failures.
- D
Use a regional HTTP(S) load balancer with a regional MIG and Cloud SQL with cross-region replication.
Why wrong: Regional load balancer cannot reroute to another region; Cloud SQL cross-region replication is asynchronous with potential data loss.
Google PCA Ensure solution and operations reliability Practice Question
This PCA practice question tests your understanding of ensure solution and operations reliability. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Your company runs a critical multi-tier application: a global HTTP(S) load balancer, multiple regional managed instance groups (MIGs) for the web tier, and Cloud Spanner for the data tier. You need to design for zone-level and region-level failures. What architecture ensures the highest availability?
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 a global HTTP(S) load balancer with regional MIGs in multiple regions, each spanning zones, and a multi-region Cloud Spanner instance.
Option C is correct because it combines a global HTTP(S) load balancer (which can route traffic to healthy backends across regions), regional MIGs that span multiple zones within each region (providing zone-level redundancy), and a multi-region Cloud Spanner instance (which provides synchronous replication across regions for strong consistency and automatic failover). This architecture ensures that if an entire zone or region fails, traffic is automatically redirected to healthy backends in other zones/regions, and Spanner continues to serve reads and writes without manual intervention.
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.
- ✗
Use a global HTTP(S) load balancer with a single global MIG and a multi-region Cloud Spanner instance.
Why it's wrong here
There is no global MIG; MIGs are per region.
- ✗
Use a global HTTP(S) load balancer with a single zonal MIG and Cloud Spanner single-region.
Why it's wrong here
A single zonal MIG can't tolerate zone failure; single-region Spanner can't survive region failure.
- ✓
Use a global HTTP(S) load balancer with regional MIGs in multiple regions, each spanning zones, and a multi-region Cloud Spanner instance.
Why this is correct
Regional MIGs across zones handle zone failures; multiple regions and multi-region Spanner handle region failures.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use a regional HTTP(S) load balancer with a regional MIG and Cloud SQL with cross-region replication.
Why it's wrong here
Regional load balancer cannot reroute to another region; Cloud SQL cross-region replication is asynchronous with potential data loss.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the distinction between 'regional' and 'global' load balancers, and the trap here is that candidates might choose a regional load balancer (Option D) thinking it is sufficient, but it cannot route traffic across regions, making it unsuitable for region-level failure recovery.
Detailed technical explanation
How to think about this question
The global HTTP(S) load balancer uses Google Front End (GFE) instances distributed globally, which terminate TLS and route traffic to the closest healthy backend based on the 'global' load balancing policy. Regional MIGs with autohealing and autoscaling ensure that failed instances are replaced within the same zone, while multi-region Cloud Spanner uses Paxos-based synchronous replication across regions, guaranteeing strong consistency and an RPO of zero even during a regional outage. In practice, this design is used by large-scale applications like Google Ads and YouTube to achieve 99.999% availability.
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
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this PCA question test?
Ensure solution and operations reliability — This question tests Ensure solution and operations reliability — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use a global HTTP(S) load balancer with regional MIGs in multiple regions, each spanning zones, and a multi-region Cloud Spanner instance. — Option C is correct because it combines a global HTTP(S) load balancer (which can route traffic to healthy backends across regions), regional MIGs that span multiple zones within each region (providing zone-level redundancy), and a multi-region Cloud Spanner instance (which provides synchronous replication across regions for strong consistency and automatic failover). This architecture ensures that if an entire zone or region fails, traffic is automatically redirected to healthy backends in other zones/regions, and Spanner continues to serve reads and writes without manual intervention.
What should I do if I get this PCA 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: Jun 30, 2026
This PCA 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 PCA exam.
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