The answer is to set both the LeaseBlob property to True and the ScanBlob property to True in your BlobTrigger binding. LeaseBlob acquires a blob lease before the function executes, preventing any other process—including ongoing writes—from modifying the blob, which directly avoids partial blob processing. ScanBlob forces the trigger to inspect the blob’s metadata and content to confirm it is fully written before firing, adding an extra verification layer. On the AZ-204 exam, this tests your understanding of Azure Functions blob trigger reliability patterns, often appearing as a two-answer question where candidates mistakenly choose only one option or confuse ScanBlob with polling intervals. A common trap is thinking a simple delay or retry policy suffices, but leases and content scanning are the official safeguards. Memory tip: “Lease locks it, Scan checks it”—both must be true to avoid processing partially written blobs.
AZ-204 Develop Azure compute solutions Practice Question
This AZ-204 practice question tests your understanding of develop azure compute solutions. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 creating an Azure Functions app that uses a Blob Storage trigger to process new files. The function must process files only when they are completely written (i.e., no ongoing writes). You need to avoid processing partially written files. Which TWO configurations should you consider?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use the 'BlobTrigger' with the 'LeaseBlob' property set to 'True'.
Option D is correct because setting the 'LeaseBlob' property to 'True' in the BlobTrigger binding acquires a lease on the blob before processing, ensuring that no other process (including ongoing writes) can modify the blob. This prevents processing partially written files. Option E is correct because setting 'ScanBlob' to 'True' forces the trigger to scan the blob's metadata and content to verify it is complete before firing, which helps avoid triggering on incomplete writes.
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.
✗
Increase the 'BatchSize' to reduce the frequency of trigger evaluations.
Why it's wrong here
BatchSize does not affect file completeness detection.
✗
Check the blob's 'LastModified' timestamp in the function code to verify no recent changes.
Why it's wrong here
LastModified can still be updated during writes.
✗
Use a timer-triggered function that lists blobs and processes those with a stable size.
Why it's wrong here
This is a workaround but not a built-in feature of Blob trigger.
✓
Use the 'BlobTrigger' with the 'LeaseBlob' property set to 'True'.
Why this is correct
LeaseBlob ensures the blob is committed and not being written.
Related concept
Read the scenario before looking for a memorised answer.
✓
Set the 'ScanBlob' property to 'True' in the trigger binding.
Why this is correct
ScanBlob enables scanning for new blobs and ensures they are fully written.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse 'BatchSize' or 'LastModified' checks as solutions for partial writes, when in fact the correct native mechanisms are blob leasing and scan verification, which are directly configurable in the trigger binding.
Detailed technical explanation
How to think about this question
Under the hood, the BlobTrigger uses Azure Storage's lease mechanism to acquire an infinite-duration lease (if 'LeaseBlob' is true) before invoking the function, which prevents other writers from modifying the blob during processing. The 'ScanBlob' property, when set to true, instructs the trigger to perform a HEAD request to verify blob metadata (e.g., content length) and ensure the blob is not in a 'pending' state from an ongoing write operation. In real-world scenarios, such as large file uploads via Azure File Sync or multipart uploads, these settings are critical to avoid processing incomplete data.
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.
TExam Day Tips
→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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-204 question in full detail.
Develop Azure compute solutions — This question tests Develop Azure compute solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use the 'BlobTrigger' with the 'LeaseBlob' property set to 'True'. — Option D is correct because setting the 'LeaseBlob' property to 'True' in the BlobTrigger binding acquires a lease on the blob before processing, ensuring that no other process (including ongoing writes) can modify the blob. This prevents processing partially written files. Option E is correct because setting 'ScanBlob' to 'True' forces the trigger to scan the blob's metadata and content to verify it is complete before firing, which helps avoid triggering on incomplete writes.
What should I do if I get this AZ-204 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This AZ-204 practice question is part of Courseiva's free Microsoft 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 AZ-204 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.