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GCDL Practice Question: A development team builds a mobile app using…
This GCDL practice question tests your understanding of a development team builds a mobile app using…. 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.
A development team builds a mobile app using Firebase. They need a real-time database that syncs data across all connected clients instantly (e.g., a collaborative to-do app where all users see updates in real-time). Which Firebase/Google Cloud service provides this?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
Cloud Pub/Sub subscriptions on the mobile clients.
While Pub/Sub delivers messages, mobile clients don't directly subscribe to Pub/Sub topics. Firebase SDKs abstract the real-time synchronization mechanism for mobile/web clients.
B
Best answer
Cloud Firestore or Firebase Realtime Database for real-time data sync across all connected clients.
Firestore provides real-time listeners — when data changes, the SDK automatically delivers updates to all subscribed clients. This enables truly real-time collaborative apps without polling.
C
Distractor review
BigQuery streaming inserts for real-time data delivery to mobile clients.
BigQuery streaming inserts write analytical data to BigQuery — it's not designed for real-time client-facing data synchronization in mobile apps.
D
Distractor review
Cloud SQL with read replicas to distribute updates to clients.
Cloud SQL is a relational database for traditional applications. It doesn't provide native real-time client synchronization — clients would need to poll for updates.
Common exam trap
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Technical deep dive
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- 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.
Related practice questions
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More questions from this exam
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Question 1
A traditional retailer currently maintains its own data centers, purchasing servers every 3–5 years and paying for facilities, power, and staff regardless of demand. When it migrates its workloads to the public cloud, which change in cost model does it experience?
Question 2
An e-commerce company plans its infrastructure for peak shopping events (e.g., Black Friday) which drive 50× normal traffic. On-premises, they must maintain 50× capacity year-round. In the cloud, they provision 50× capacity only during peak periods. Which cloud characteristic enables this cost optimization?
Question 3
Which term describes the process by which organizations integrate digital technology into all areas of their business, fundamentally changing how they operate and deliver value to customers?
Question 4
When a company moves from maintaining its own data center to using Google Cloud, which operational responsibility does Google assume that the company previously managed?
Question 5
A hospital runs a patient records system that must remain on-premises due to strict regulatory data residency requirements. However, they also want to use cloud-based AI for diagnostic imaging analysis. Which cloud deployment model best describes their architecture?
Question 6
What is virtualization in the context of cloud computing, and why is it fundamental to how cloud providers deliver services?
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FAQ
Questions learners often ask
What does this GCDL question test?
Read the scenario before looking for a memorised answer.
What is the correct answer to this question?
The correct answer is: Cloud Firestore or Firebase Realtime Database for real-time data sync across all connected clients. — Firebase Realtime Database and Cloud Firestore both provide real-time data synchronization. When data changes, all connected clients receive the update automatically without polling. Firestore (Firebase's newer NoSQL database) is the recommended choice — it scales better and provides offline support, strong consistency, and a more expressive query model. Firebase is Google's mobile and web application development platform, tightly integrated with Google Cloud.
What should I do if I get this GCDL question wrong?
Identify which GCDL exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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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.