- A
Replace the Blob Storage trigger with an Event Grid trigger and create a Blob Created event subscription that targets the Function's endpoint
Event Grid delivers blob creation events within seconds of the upload by pushing events rather than polling. The Function receives the event payload (which includes the blob URI) and begins processing immediately. This eliminates the polling delay inherent in the Blob Storage trigger on large accounts.
- B
Switch to a Timer trigger that runs every 30 seconds and lists newly created blobs via the SDK
Why wrong: A 30-second timer still introduces up to 30 seconds of latency and requires the Function to query blob metadata on every timer fire — adding SDK calls and complexity. Event Grid push-based delivery is faster and simpler.
- C
Use a Queue Storage trigger and write blob metadata to the queue from the upload client
Why wrong: This approach requires modifying the upload client to write queue messages, adding a dependency between the uploader and the processing pipeline. Event Grid decouples the producer (blob upload) from the consumer (Function) without requiring changes to the upload side.
- D
Move the Function to a Premium plan, which uses a dedicated worker and eliminates Blob trigger polling delays
Why wrong: The Premium plan eliminates cold starts and provides VNET integration, but it does not change the fundamental polling mechanism of the Blob Storage trigger. The polling delay on large accounts affects all hosting plans equally.
Quick Answer
The correct answer is to replace the Blob Storage trigger with an Event Grid trigger and subscribe to Blob Created events. This works because the default Blob Storage trigger relies on polling Azure Storage logs, which can introduce up to 10 minutes of latency in high-volume accounts with many containers and blobs. Event Grid, by contrast, delivers events via HTTP webhook in near real time—typically under one second—so your function fires the instant a blob is uploaded. On the AZ-204 exam, this scenario tests your understanding of event-driven architectures versus polling-based triggers; a common trap is assuming a Blob trigger is always sufficient, even under scale. Remember the key distinction: Blob triggers poll logs, Event Grid pushes events. For a quick memory tip, think “Polling is slow, pushing is pro”—if you need seconds, push with Event Grid.
AZ-204 Practice Question: Event Grid trigger to replace Blob Storage…
This AZ-204 practice question tests your understanding of develop azure compute solutions. 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. A key principle to apply: azure Functions. 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.
Images are uploaded to a high-volume Blob Storage account. An Azure Function with a Blob Storage trigger processes each new image. The team has observed processing delays of up to 10 minutes on accounts with large numbers of containers and blobs. They need processing to start within seconds of upload. What should the developer change?
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
Replace the Blob Storage trigger with an Event Grid trigger and create a Blob Created event subscription that targets the Function's endpoint
Option A is correct because Event Grid provides near-real-time event delivery (typically under 1 second) for Blob Created events, eliminating the polling latency inherent in the Blob Storage trigger. The Blob Storage trigger polls Azure Storage logs for new blobs, which can cause delays of up to 10 minutes in high-volume accounts with many containers and blobs. By switching to an Event Grid trigger, the function is invoked directly via HTTP webhook as soon as the blob is created, meeting the requirement for processing to start within seconds.
Key principle: Azure 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.
- ✓
Replace the Blob Storage trigger with an Event Grid trigger and create a Blob Created event subscription that targets the Function's endpoint
Why this is correct
Event Grid delivers blob creation events within seconds of the upload by pushing events rather than polling. The Function receives the event payload (which includes the blob URI) and begins processing immediately. This eliminates the polling delay inherent in the Blob Storage trigger on large accounts.
Related concept
Azure Functions
- ✗
Switch to a Timer trigger that runs every 30 seconds and lists newly created blobs via the SDK
Why it's wrong here
A 30-second timer still introduces up to 30 seconds of latency and requires the Function to query blob metadata on every timer fire — adding SDK calls and complexity. Event Grid push-based delivery is faster and simpler.
- ✗
Use a Queue Storage trigger and write blob metadata to the queue from the upload client
Why it's wrong here
This approach requires modifying the upload client to write queue messages, adding a dependency between the uploader and the processing pipeline. Event Grid decouples the producer (blob upload) from the consumer (Function) without requiring changes to the upload side.
- ✗
Move the Function to a Premium plan, which uses a dedicated worker and eliminates Blob trigger polling delays
Why it's wrong here
The Premium plan eliminates cold starts and provides VNET integration, but it does not change the fundamental polling mechanism of the Blob Storage trigger. The polling delay on large accounts affects all hosting plans equally.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume upgrading the hosting plan (Premium) will fix latency issues, but the root cause is the polling-based Blob Storage trigger, not the underlying infrastructure; the correct solution is to switch to an event-driven trigger like Event Grid.
Detailed technical explanation
How to think about this question
Event Grid uses a push model with HTTP webhooks, delivering events within 500ms on average, while the Blob Storage trigger uses a pull model that polls Azure Storage analytics logs (specifically the $logs container) every few minutes. In high-volume accounts with thousands of containers, the log scanning can take up to 10 minutes due to the sheer number of log entries. Event Grid also supports advanced filtering (e.g., by blob name prefix or suffix), which can reduce unnecessary invocations and improve efficiency.
KKey Concepts to Remember
- Azure Functions
- Event Grid trigger
- Blob Storage trigger polling delay
- near-real-time processing
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
Azure Functions
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.
What to study next
Got this wrong? Here's your next step.
Review azure Functions, then practise related AZ-204 questions on the same topic to reinforce the concept.
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Develop Azure compute solutions practice questions
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FAQ
Questions learners often ask
What does this AZ-204 question test?
Develop Azure compute solutions — This question tests Develop Azure compute solutions — Azure Functions.
What is the correct answer to this question?
The correct answer is: Replace the Blob Storage trigger with an Event Grid trigger and create a Blob Created event subscription that targets the Function's endpoint — Option A is correct because Event Grid provides near-real-time event delivery (typically under 1 second) for Blob Created events, eliminating the polling latency inherent in the Blob Storage trigger. The Blob Storage trigger polls Azure Storage logs for new blobs, which can cause delays of up to 10 minutes in high-volume accounts with many containers and blobs. By switching to an Event Grid trigger, the function is invoked directly via HTTP webhook as soon as the blob is created, meeting the requirement for processing to start within seconds.
What should I do if I get this AZ-204 question wrong?
Review azure Functions, then practise related AZ-204 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
Azure Functions
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Last reviewed: Jun 11, 2026
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.
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