Cloud Digital Leader Google Cloud Products and Services Practice Question
A developer wants to build a mobile app backend that uses a real-time database for chat messages, user profiles, and file storage for images. They want a fully managed, serverless solution. Which THREE Google Cloud services should they use? (Choose three.)
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 Functions
Firestore provides real-time document database for chat and profiles; Cloud Storage for images; Cloud Functions for backend logic triggered by database or storage events. App Engine is not required for serverless backend if using Cloud Functions.
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
Why it's wrong here
Cloud SQL is a fully managed relational database (MySQL/PostgreSQL/SQL Server) that requires a schema and does not offer real-time NoSQL semantics like document snapshots or client-side sync. It would not give the chat/user profile data a fast, offline-first mobile experience, and running it adds connection management overhead the serverless architecture avoids.
- ✓
Cloud Functions
Why this is correct
Cloud Functions is a serverless execution environment that runs backend logic in response to Firestore and Cloud Storage events, so you can handle message processing, profile updates, and media metadata without provisioning servers. It naturally complements the mobile backend by creating a scalable, event-driven pipeline that charges only when code runs, and it provides a secure way to perform privileged operations that should not run on the client device.
- ✓
Firestore
Why this is correct
Firestore is a real-time NoSQL document database with mobile SDKs that push snapshot changes to clients, making it the right choice for chat messages, user profiles, and presence indicators. It supports offline persistence and transactions, which lets chat rooms and profile updates work seamlessly even with flaky connectivity, and its server-side rules handle basic validation and access control.
- ✓
Cloud Storage
Why this is correct
Cloud Storage is the object store for photos, videos, and other binary files that a mobile app backend needs; profile images and chat attachments are uploaded directly using Firebase Storage SDK with signed URLs and security rules. While it is not a database, it is a required companion service so Firestore stores only metadata and does not become bloated with large media objects.
- ✗
App Engine
Why it's wrong here
App Engine is a PaaS hosting environment for always-on web applications and REST APIs, but building this mobile backend with Cloud Functions and Firestore eliminates the need for an entire web server tier. Choosing App Engine would force you to manage request routing and scaling for a service that only needs discrete, short-lived event-triggered operations, making it a heavier and less flexible fit for an event-driven mobile backend.
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 |
Go deeper
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Cloud Digital Transformation
Key term
Firestore
Firestore is a flexible, scalable, serverless NoSQL database from Google Cloud that automatically syncs data across applications in real time.
Key term
Cloud Functions
Cloud Functions are serverless compute services that let you run single-purpose code in response to events without managing servers.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This GCDL 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 GCDL exam.