The answer is Azure Event Grid to trigger an Azure Function on blob creation, which validates the file and moves it after the scan. This approach is the most cost-effective and scalable because Event Grid provides a fully managed, serverless event routing service that reacts to blob uploads in real time, while the Azure Function performs the malware scanning using Microsoft Defender for Cloud Apps as a long-running, event-driven process. On the AZ-204 exam, this scenario tests your understanding of implementing event-driven architectures with Azure services, specifically how to decouple storage events from compute without idle costs. A common trap is choosing a VM-based solution, which incurs costs even when idle and requires manual scaling, or Logic Apps, which can be more expensive for long-running validations. The key memory tip is “Event Grid triggers, Function scans, Blob moves”—think of the three-step pipeline that keeps costs low by only running compute when a file arrives.
AZ-204 Practice Question: Connect to and consume Azure services and third-party services
This AZ-204 practice question tests your understanding of connect to and consume azure services and third-party services. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
You are developing a solution that processes large files uploaded by users to Azure Blob Storage. Each file must be validated for malware using Microsoft Defender for Cloud Apps before being moved to a different container for further processing. The validation can take several minutes. What is the most cost-effective and scalable approach?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use Azure Event Grid to trigger an Azure Function on blob creation, which validates the file and moves it after scan.
Azure Event Grid can trigger an Azure Function when a blob is created. The function can use Defender for Cloud Apps (or Microsoft Defender XDR) to scan the file. This is event-driven, scalable, and cost-effective. Option A is correct. Option B is incorrect because using a VM would require manual scaling and incur costs even when idle. Option C is incorrect because Logic Apps may be more expensive for long-running operations. Option D is incorrect because the SDK polling is inefficient and not real-time.
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 Azure Event Grid to trigger an Azure Function on blob creation, which validates the file and moves it after scan.
Why this is correct
Event-driven, serverless, and cost-effective.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use the Azure SDK to poll for new blobs from within a continuously running background service.
Why it's wrong here
Polling is inefficient and not scalable.
✗
Use an Azure VM running a scheduled task to poll for new blobs and perform validation.
Use Azure Logic Apps with a recurrence trigger to check for new blobs and call the Microsoft Defender API.
Why it's wrong here
Logic Apps may have higher cost for long-running scans.
Common exam traps
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.
Detailed technical explanation
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.
Real-world example
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-204 question in full detail.
Identify which AZ-204 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.
Connect to and consume Azure services and third-party services — This question tests Connect to and consume Azure services and third-party services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use Azure Event Grid to trigger an Azure Function on blob creation, which validates the file and moves it after scan. — Azure Event Grid can trigger an Azure Function when a blob is created. The function can use Defender for Cloud Apps (or Microsoft Defender XDR) to scan the file. This is event-driven, scalable, and cost-effective. Option A is correct. Option B is incorrect because using a VM would require manual scaling and incur costs even when idle. Option C is incorrect because Logic Apps may be more expensive for long-running operations. Option D is incorrect because the SDK polling is inefficient and not real-time.
What should I do if I get this AZ-204 question wrong?
Identify which AZ-204 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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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