AZ-204 Develop Azure compute solutions Practice Question
You are developing a solution that processes large files uploaded to Azure Blob Storage. Each file must be processed by a long-running operation that may take up to 30 minutes. You need to use Azure Functions with a consumption plan. How should you handle the processing?
⚠ Common exam trap
Many exam-takers assume increasing the function timeout or using a retry policy can solve long-running operations, but they overlook the hard 10-minute limit on Consumption Plan and the need for a stateful orchestration pattern like Durable Functions.
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
✓
Use Durable Functions with a blob-triggered client function
D is correct because Azure Functions on a Consumption Plan have a default timeout of 5 minutes and a maximum of 10 minutes. A blob-triggered client function can start a Durable Functions orchestration, which can run for up to 30 minutes (or longer) by using the orchestration's timeout and retry capabilities, avoiding the Consumption Plan's timeout limit.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use a Blob trigger function with a retry policy
Why it's wrong here
A standard Blob trigger function, even when configured with a retry policy, is fundamentally limited by the maximum execution timeout of its hosting plan. For an Azure Functions Consumption plan, this limit is 15 minutes. A retry policy will only re-execute the function from the beginning after a timeout or failure; it does not extend the duration of a single function invocation, thus failing to address the core problem of a process that exceeds the allowed execution time.
- ✗
Increase the function timeout to 30 minutes
Why it's wrong here
While Azure Functions allows configuring the timeout duration, the maximum execution time for a function running on the Consumption plan is strictly capped at 15 minutes. Attempting to set a timeout value higher than this limit will be ignored or result in an error, as it is an inherent constraint of the Consumption plan's cost-effective, serverless model. To achieve a 30-minute timeout, a more expensive Premium or App Service Plan would be required.
- ✗
Use an Event Grid trigger function to process the blob
Why it's wrong here
An Event Grid trigger function, despite using a different event source, operates under the same execution timeout constraints as other Azure Functions on the Consumption plan. It will still be subject to the default 10-minute or maximum 15-minute execution limit. Event Grid's role is to efficiently deliver events, not to alter the runtime environment or extend the processing duration capabilities of the triggered function itself for long-running tasks.
- ✓
Use Durable Functions with a blob-triggered client function
Why this is correct
Durable Functions are purpose-built for orchestrating long-running, stateful workflows that can inherently exceed the standard Azure Functions timeout limits. A blob-triggered client function can initiate a Durable Orchestration, which then manages the execution of multiple activity functions, persisting its state between asynchronous operations. This allows the overall workflow to run for hours or even days by breaking down the large file processing into smaller, manageable, and independently executable steps.
Quick reference
Azure Blob Storage Tier Comparison
| Tier | Storage Cost | Retrieval Cost | Latency | Use Case |
|---|---|---|---|---|
| Hot | Highest | Lowest | Immediate | Active data, frequent reads |
| Cool | Lower | Higher | Immediate | Data accessed < once / month |
| Cold | Lower still | Higher | Immediate | Data accessed < once / quarter |
| Archive | Lowest | Highest + rehydration delay | Hours | Long-term compliance retention |
Go deeper
Related to this question
Learn chapter
Azure Functions Development
Key term
Durable Functions
Durable Functions is an extension of Azure Functions that lets you write stateful workflows in code, managing complex sequences of tasks, retries, and delays automatically.
Key term
Azure Functions Bindings
Azure Functions Bindings are declarative connections that link your serverless function code to Azure services or external resources, handling input and output data automatically without writing extra networking or authentication code.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.