The answer is Azure Blob Storage trigger and Azure Event Grid trigger, as both services can invoke an Azure Function when a new blob is added to a container. The Blob Storage trigger uses a polling mechanism to detect new blobs, while the Event Grid trigger subscribes to blob-created events for near-real-time, event-driven execution. On the AZ-204 exam, this distinction tests your understanding of event-driven architecture versus polling-based triggers, and a common trap is assuming only the Blob Storage trigger works for new blobs—Event Grid is actually the preferred, lower-latency option for production scenarios. Remember the memory tip: “Poll for old, Grid for gold”—the Blob Storage trigger is fine for simple cases, but Event Grid is the gold standard for reliable, low-latency blob creation events.
AZ-204 Develop Azure compute solutions Practice Question
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. 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.
Which TWO Azure services can be used to trigger an Azure Function when a new blob is added to an Azure Storage container? (Choose two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Azure Event Grid trigger
Option A is correct because Azure Event Grid trigger enables an Azure Function to be invoked automatically when a new blob is created in a Storage account. Event Grid provides a reliable, low-latency event-driven architecture that supports blob created events, making it a valid trigger for this scenario.
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.
✓
Azure Event Grid trigger
Why this is correct
Event Grid can be set up with a Blob Created event to trigger the function.
Related concept
Read the scenario before looking for a memorised answer.
✗
Azure Queue Storage trigger
Why it's wrong here
Queue Storage trigger responds to messages in a queue, not blob creation.
✓
Azure Blob Storage trigger
Why this is correct
The Blob Storage trigger automatically fires when a new or updated blob is detected.
Related concept
Read the scenario before looking for a memorised answer.
✗
Azure Cosmos DB trigger
Why it's wrong here
Cosmos DB trigger responds to changes in a Cosmos DB container, not blob storage.
✗
HTTP trigger
Why it's wrong here
HTTP trigger requires an explicit HTTP request, not a blob event.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume only the Blob Storage trigger can react to blob creation, overlooking Event Grid as a valid alternative, or they mistakenly think Queue Storage or Cosmos DB triggers can be repurposed for blob events.
Detailed technical explanation
How to think about this question
Under the hood, the Blob Storage trigger uses Azure Storage logs and a polling mechanism to detect new blobs, which can introduce latency of up to several minutes. In contrast, Event Grid trigger uses a push model with sub-second latency, making it ideal for real-time processing. A subtle behavior is that the Blob Storage trigger may miss blobs if the container is heavily loaded or if the function app scales out, whereas Event Grid guarantees at-least-once delivery.
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: Azure Event Grid trigger — Option A is correct because Azure Event Grid trigger enables an Azure Function to be invoked automatically when a new blob is created in a Storage account. Event Grid provides a reliable, low-latency event-driven architecture that supports blob created events, making it a valid trigger for this scenario.
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.
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Question Discussion
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