The correct answer is to configure the Event Hubs trigger with the Event Scale mode and set the target to one instance per partition. This configuration ensures that Azure Functions automatically scales out to match the number of Event Hub partitions, with each function instance processing events from at least one partition, which is essential for maintaining event ordering and achieving optimal throughput. On the AZ-204 exam, this scenario tests your understanding of the runtime scaling provider for Event Hubs, specifically how the Event Scale mode differs from the default compute-based scaling; a common trap is choosing the wrong scaling mode or forgetting that the partition count drives the instance count. Remember the mnemonic "One Partition, One Instance" — when you need dedicated partition processing, always pair the Event Scale mode with a target of one instance per partition to guarantee that each function instance owns at least one partition.
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 developing an Azure Functions app that processes events from an Event Hubs instance. The function must scale out automatically based on the number of partitions in the Event Hub. You need to ensure that each function instance processes events from at least one partition. Which THREE configurations should you use?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "least"
Why it matters: You want the option with minimum overhead, fewest steps, or lowest impact — not the most feature-rich or comprehensive answer.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Set the function app to use the 'Event Scale' mode with a target of one instance per partition.
Option A is correct because the 'Event Scale' mode with a target of one instance per partition ensures that the function app scales out to match the number of Event Hub partitions, with each instance processing events from at least one partition. This mode is specifically designed for event-driven scaling with Event Hubs, guaranteeing that each partition is processed by a dedicated instance for optimal throughput and ordering.
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.
✓
Set the function app to use the 'Event Scale' mode with a target of one instance per partition.
Why this is correct
Event Scale mode maximizes parallelism per partition.
Clue confirmation
The clue word "least" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Set the 'MaxBatchSize' property to 1 to ensure even distribution.
Why it's wrong here
Batch size does not affect partition distribution.
✓
Configure the function to use an event processor host with blob storage for checkpointing.
The clue word "least" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Select the Premium App Service plan for the function app.
Why it's wrong here
Premium plan is not required for partition distribution.
✓
Use the EventHubs trigger with the 'PartitionKey' parameter set to the partition ID.
Why this is correct
Partition key ensures events from a partition go to the same instance.
Clue confirmation
The clue word "least" in the question point toward this answer.
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 confuse batch size configuration (MaxBatchSize) with scaling behavior, or assume a Premium plan is mandatory for partition-level scaling, when in fact the Event Scale mode and checkpointing are the key mechanisms.
Detailed technical explanation
How to think about this question
Under the hood, the Event Hubs trigger uses an event processor host (EPH) that leases partitions among function instances via blob storage checkpointing. The 'Event Scale' mode configures the host to target one lease per instance, ensuring each instance owns at least one partition. This is critical for maintaining event ordering within a partition and avoiding duplicate processing when scaling out.
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: Set the function app to use the 'Event Scale' mode with a target of one instance per partition. — Option A is correct because the 'Event Scale' mode with a target of one instance per partition ensures that the function app scales out to match the number of Event Hub partitions, with each instance processing events from at least one partition. This mode is specifically designed for event-driven scaling with Event Hubs, guaranteeing that each partition is processed by a dedicated instance for optimal throughput and ordering.
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: "least". You want the option with minimum overhead, fewest steps, or lowest impact — not the most feature-rich or comprehensive answer.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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