- A
Implement a buffer using Azure Blob storage: the Event Hubs triggered function writes raw data to blobs, and a separate timer-triggered function batches and writes to Cosmos DB at a controlled rate.
This decouples ingestion from storage, prevents Cosmos DB overload, and controls cost by batching writes.
- B
Configure the Event Hubs trigger to use a checkpointing strategy with a larger batch size to reduce the number of function invocations.
Why wrong: Larger batch size can help but does not guarantee Cosmos DB won't be overloaded; checkpointing ensures no data loss but does not control write rate.
- C
Use Azure Stream Analytics to process the Event Hubs data and write directly to Cosmos DB.
Why wrong: Stream Analytics can handle high throughput but adds cost and latency; it may still cause throttling if the output rate exceeds Cosmos DB capacity.
- D
Increase the provisioned throughput (RU/s) on the Cosmos DB container to handle peak loads.
Why wrong: This can be costly and may still result in throttling if the increase is not enough; also, it doesn't prevent message loss from Event Hubs.
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.
Your company is developing a real-time dashboard that displays live metrics from IoT devices. The backend processes device data using Azure Functions with an Event Hubs trigger. The processed data is stored in Azure Cosmos DB. You need to ensure that the system can handle a sudden increase in device data without losing messages or overloading Cosmos DB. The solution must minimize latency and cost. What should you do?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"minimum / minimize"Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
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
Implement a buffer using Azure Blob storage: the Event Hubs triggered function writes raw data to blobs, and a separate timer-triggered function batches and writes to Cosmos DB at a controlled rate.
Option A is correct because it decouples the ingestion rate from the write rate to Cosmos DB. By buffering raw data in Azure Blob storage and using a timer-triggered function to batch-write at a controlled rate, the system can absorb sudden spikes in device data without overwhelming Cosmos DB or losing messages. This approach minimizes latency by keeping the Event Hubs trigger processing fast (writing to blob) and reduces cost by avoiding the need to over-provision RU/s on Cosmos DB.
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.
- ✓
Implement a buffer using Azure Blob storage: the Event Hubs triggered function writes raw data to blobs, and a separate timer-triggered function batches and writes to Cosmos DB at a controlled rate.
Why this is correct
This decouples ingestion from storage, prevents Cosmos DB overload, and controls cost by batching writes.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Configure the Event Hubs trigger to use a checkpointing strategy with a larger batch size to reduce the number of function invocations.
Why it's wrong here
Larger batch size can help but does not guarantee Cosmos DB won't be overloaded; checkpointing ensures no data loss but does not control write rate.
- ✗
Use Azure Stream Analytics to process the Event Hubs data and write directly to Cosmos DB.
Why it's wrong here
Stream Analytics can handle high throughput but adds cost and latency; it may still cause throttling if the output rate exceeds Cosmos DB capacity.
- ✗
Increase the provisioned throughput (RU/s) on the Cosmos DB container to handle peak loads.
Why it's wrong here
This can be costly and may still result in throttling if the increase is not enough; also, it doesn't prevent message loss from Event Hubs.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume increasing throughput or batch size is the simplest solution, but the exam tests the understanding that decoupling ingestion from processing with a buffer is the correct way to handle sudden load spikes while minimizing cost and latency.
Trap categories for this question
Command / output trap
Stream Analytics can handle high throughput but adds cost and latency; it may still cause throttling if the output rate exceeds Cosmos DB capacity.
Detailed technical explanation
How to think about this question
Under the hood, the Event Hubs trigger uses checkpointing to track processed events, but it does not inherently rate-limit writes to downstream services. By using Azure Blob storage as an intermediate buffer, the system leverages blob's high-throughput, low-cost storage to absorb bursts, and the timer-triggered function can implement a controlled batch write pattern (e.g., using the Cosmos DB bulk executor SDK) to optimize RU consumption and avoid 429 throttling errors. This pattern is similar to the 'queue-based load leveling' pattern, which is essential for handling unpredictable IoT data spikes without over-provisioning.
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 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.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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 — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Implement a buffer using Azure Blob storage: the Event Hubs triggered function writes raw data to blobs, and a separate timer-triggered function batches and writes to Cosmos DB at a controlled rate. — Option A is correct because it decouples the ingestion rate from the write rate to Cosmos DB. By buffering raw data in Azure Blob storage and using a timer-triggered function to batch-write at a controlled rate, the system can absorb sudden spikes in device data without overwhelming Cosmos DB or losing messages. This approach minimizes latency by keeping the Event Hubs trigger processing fast (writing to blob) and reduces cost by avoiding the need to over-provision RU/s on Cosmos DB.
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.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 24, 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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