Quick Answer
The correct answer is the fan-out/fan-in pattern, because it is specifically designed to execute multiple independent tasks in parallel and then aggregate their results before proceeding. In Durable Functions, this is implemented using `Task.WhenAll()` to fan out calls to activity functions and then fan in the results, which perfectly matches the requirement of calling five independent booking activities and waiting for all of them to complete. On the AZ-204 exam, this pattern tests your understanding of orchestrator function constraints and parallel execution, often appearing in scenarios like batch processing or multi-service API calls. A common trap is confusing this with the chaining pattern, which runs tasks sequentially, or the monitor pattern, which polls for a state change. Remember the memory tip: “Fan out to all, fan in to call”—if you need to wait for every parallel task, think `Task.WhenAll()`.
This AZ-204 practice question tests your understanding of develop azure compute solutions. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
A Durable Functions workflow for a booking backend must call five independent activity functions and continue only after all results are available. Which pattern is appropriate?
Monitor pattern
Why wrong: Monitor pattern periodically checks external state.
Fan-out/fan-in
Fan-out/fan-in runs activities in parallel and aggregates results after all complete.
Human interaction
Why wrong: Human interaction waits for external manual approval or event.
Function chaining
Why wrong: Function chaining runs steps sequentially.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Fan-out/fan-in
The fan-out/fan-in pattern is designed for scenarios where multiple independent tasks must execute in parallel, and the workflow must wait for all results before proceeding. In Durable Functions, this is implemented using `Task.WhenAll()` to fan out activity function calls and then aggregate their results, which matches the requirement of calling five independent activities and continuing only after all results are available.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Monitor pattern
Why it's wrong here
Monitor pattern periodically checks external state.
Fan-out/fan-in
Why this is correct
Fan-out/fan-in runs activities in parallel and aggregates results after all complete.
Related concept
Read the scenario before looking for a memorised answer.
Human interaction
Why it's wrong here
Human interaction waits for external manual approval or event.
Function chaining
Why it's wrong here
Function chaining runs steps sequentially.
Common exam traps
The trap here is that candidates often confuse the fan-out/fan-in pattern with function chaining, mistakenly thinking that sequential execution is sufficient, or they incorrectly apply the Monitor pattern when the requirement is simply parallel execution without polling.
Detailed technical explanation
Under the hood, the fan-out/fan-in pattern in Durable Functions leverages the orchestration's ability to schedule multiple activity function tasks concurrently using `Task.WhenAll()`. The orchestration history tracks each activity's completion, and the runtime ensures that the orchestration resumes only after all parallel tasks have returned, using the durable task hub's queue-based coordination. In real-world scenarios, this pattern is critical for workflows like aggregating data from multiple microservices or processing batch jobs where latency is reduced by parallelizing independent operations.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Develop Azure compute solutions — study guide chapter
Learn the concepts, then practise the questions
Develop Azure compute solutions practice questions
Targeted practice on this topic area only
All AZ-204 questions
997 questions across all exam domains
Microsoft Azure Developer Associate AZ-204 study guide
Full concept coverage aligned to exam objectives
AZ-204 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise AZ-204 questions linked to Develop Azure compute solutions.
Practise AZ-204 questions linked to Develop for Azure storage.
Practise AZ-204 questions linked to Implement Azure security.
Practise AZ-204 questions linked to Connect to and consume Azure services and third-party services.
Practise AZ-204 questions linked to Monitor, troubleshoot, and optimize Azure solutions.
Practise AZ-204 questions linked to AZ-204 fundamentals.
Practise AZ-204 questions linked to AZ-204 scenario.
Practise AZ-204 questions linked to AZ-204 troubleshooting.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Develop Azure compute solutions — This question tests Develop Azure compute solutions — Read the scenario before looking for a memorised answer..
The correct answer is: Fan-out/fan-in — The fan-out/fan-in pattern is designed for scenarios where multiple independent tasks must execute in parallel, and the workflow must wait for all results before proceeding. In Durable Functions, this is implemented using `Task.WhenAll()` to fan out activity function calls and then aggregate their results, which matches the requirement of calling five independent activities and continuing only after all results are available.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A Durable Functions workflow for a checkout API must call five independent activity functions and continue only after all results are available. Which pattern is appropriate?
hardWhy A: The fan-out/fan-in pattern is correct because Durable Functions provides the `CallActivityAsync` method in parallel to invoke multiple independent activity functions simultaneously, and the `Task.WhenAll` pattern waits for all results before proceeding. This matches the requirement to call five independent activities and continue only after all results are available, which is the exact definition of fan-out/fan-in.
Keep practising
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.