easyMultiple Choice
Google PCA Practice Question: A startup is building a mobile app backend that…
A startup is building a mobile app backend that requires real-time data synchronization across multiple users. They need a fully managed, serverless NoSQL database that scales automatically and supports offline persistence. Which database should they choose?
⚠ Common exam trap
PCA often tests the confusion between Firestore and Bigtable or Spanner, where candidates pick a scalable database without recognizing that only Firestore offers native real-time sync and offline persistence.
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 Firestore
Cloud Firestore is a fully managed, serverless NoSQL document database that scales automatically and provides real-time synchronization and offline persistence through client SDKs. These features directly match the mobile app backend requirements for real-time sync across users and offline support.
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 Spanner
Why it's wrong here
Cloud Spanner is a globally distributed relational database requiring provisioned compute, so it provides neither NoSQL document storage nor offline persistence for mobile clients. It is tempting because it scales horizontally and is fully managed, which would be correct for a globally consistent relational workload needing strong transactions.
- ✗
Cloud Bigtable
Why it's wrong here
Cloud Bigtable is a wide-column NoSQL store for high-throughput analytical workloads; it has no mobile SDK, offline persistence or real-time client synchronisation. It is tempting because it scales automatically and is serverless, which would be correct for large-scale time-series or IoT data at low latency.
- ✗
Cloud SQL
Why it's wrong here
Cloud SQL is a managed relational MySQL, PostgreSQL or SQL Server instance with fixed capacity, so it offers no automatic serverless scaling, NoSQL model or offline sync. It is tempting because it is fully managed, which would be correct for a conventional relational application with predictable load.
- ✓
Cloud Firestore
Why this is correct
Cloud Firestore is a fully managed, serverless NoSQL document database that scales automatically and provides real-time listeners plus native offline persistence via client SDKs. This directly satisfies the startup's requirements for multi-user synchronisation and offline operation without provisioning servers.
Visual reference
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
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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.