Google PCA Design and plan a cloud solution architecture Practice Question
A logistics company is planning a new order-tracking platform on Google Cloud. The platform must handle sudden, unpredictable spikes from holiday promotions, keep costs low during idle periods, and provide a relational store that scales reads without the team managing replication. The architect is choosing between fully managed services and self-managed alternatives. Which two design choices meet these requirements? (Choose two.)
⚠ Common exam trap
The trap here is reading fully managed as merely hosted, when services like Cloud SQL with read replicas still require the team to size, monitor, and promote replicas.
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 Cloud Spanner with a regional instance configuration, which scales reads and writes horizontally and replicates automatically.
Cloud Run scales to zero and then out automatically, which matches unpredictable promotional spikes while keeping idle cost near zero. Cloud Spanner provides a managed relational store that scales reads and writes horizontally with automatic replication, so the team never manages replicas or failover. Together they cover the compute and data tiers without the operational overhead of self-managed alternatives.
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 Cloud Spanner with a regional instance configuration, which scales reads and writes horizontally and replicates automatically.
Why this is correct
Cloud Spanner is a fully managed, horizontally scalable relational database that handles read and write scaling automatically through its regional configuration and synchronous replication. It provides strong consistency and requires no replica management or promotion scripts, satisfying the relational store requirement that scales reads without operational replication work.
- ✗
Deploy the API tier on a Compute Engine managed instance group with a fixed size sized for peak holiday traffic.
Why it's wrong here
A fixed-size managed instance group sized for peak keeps those VMs running during idle periods, so cost never drops and the team still patches and manages the instances. It does handle spikes but fails the low-idle-cost requirement and adds operational burden, making it a weaker fit than a scale-to-zero platform.
- ✗
Run PostgreSQL on Compute Engine with streaming replication to a standby VM, and use a load balancer to split reads.
Why it's wrong here
Self-managed PostgreSQL on Compute Engine puts patching, backup, replication monitoring, and failover squarely on the team, directly contradicting the desire not to manage replication. Scaling reads requires adding and configuring replicas manually, and the load balancer does not understand replication lag, so this option adds both cost and operational risk.
- ✗
Use Cloud SQL for PostgreSQL with read replicas, and have the team script replica promotion for failover.
Why it's wrong here
Cloud SQL is managed, but read replicas require the team to provision and monitor each replica, and scripting promotion reintroduces the replication management the company wants to avoid. It scales reads only after manual capacity decisions, so it does not meet the no-management requirement as cleanly as a horizontally sharded managed service.
- ✓
Run the API tier on Cloud Run, which scales to zero when idle and scales out automatically under load.
Why this is correct
Cloud Run is a fully managed container platform that scales instances up and down based on incoming requests, including scaling to zero when there is no traffic, so idle periods cost nothing. It absorbs promotional spikes without pre-provisioning and removes server management, matching the unpredictable-traffic and low-idle-cost requirements directly.
Go deeper
Related to this question
Learn chapter
Virtual Machine Instances in Compute Engine
Key term
Cloud Spanner
Cloud Spanner is a fully managed, globally distributed relational database service from Google Cloud that combines the benefits of relational database structure with horizontal scalability and strong consistency.
Key term
Data
Data is raw, unprocessed information, like numbers, words, or measurements, that can be stored, processed, and analyzed by computers.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Google Cloud exam blueprint
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.