Quick Answer
The answer is Azure Service Bus and Azure Event Hubs. Service Bus achieves exactly-once message processing through its built-in duplicate detection feature, which identifies and discards duplicate messages based on a unique message ID within a defined time window, while its message sessions ensure ordered delivery. Event Hubs, when combined with idempotent consumer logic and checkpointing via consumer groups, can also guarantee exactly-once semantics by tracking the last successfully processed offset and preventing reprocessing. On the AZ-204 exam, this question tests your understanding of messaging guarantees, with a common trap being to confuse Event Grid’s at-least-once delivery or Azure Storage Queues’ lack of deduplication with true exactly-once processing. Remember that Service Bus gives you explicit duplicate detection, while Event Hubs requires you to build idempotency into your consumer—think of it as “Service Bus does the work for you, Event Hubs trusts you to do it yourself.”
This AZ-204 practice question tests your understanding of connect to and consume azure services and third-party services. 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.
You are designing a solution that processes orders from an e-commerce website. The solution must guarantee that each order is processed exactly once. Which TWO Azure services can you use to achieve this requirement?
Azure Service Bus
Service Bus supports duplicate detection for exactly-once.
Azure Storage Queues
Why wrong: Storage queues do not guarantee exactly-once.
Azure Event Grid
Why wrong: Event Grid guarantees at-least-once delivery.
Azure Cache for Redis
Why wrong: Not a messaging service.
Azure Event Hubs
Event Hubs with checkpointing can achieve exactly-once.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Azure Service Bus
Azure Service Bus queues support message sessions and duplicate detection to ensure exactly-once processing. Azure Event Hubs with consumer groups and checkpointing can also achieve exactly-once semantics when combined with idempotent processing. Option A is correct because Service Bus provides duplicate detection. Option B is correct because Event Hubs with checkpointing can achieve exactly-once. Option C is incorrect because Azure Storage Queues do not guarantee exactly-once. Option D is incorrect because Event Grid offers at-least-once delivery. Option E is incorrect because Azure Cache for Redis is not a messaging service.
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.
Azure Service Bus
Why this is correct
Service Bus supports duplicate detection for exactly-once.
Related concept
Read the scenario before looking for a memorised answer.
Azure Storage Queues
Why it's wrong here
Storage queues do not guarantee exactly-once.
Azure Event Grid
Why it's wrong here
Event Grid guarantees at-least-once delivery.
Azure Cache for Redis
Why it's wrong here
Not a messaging service.
Azure Event Hubs
Why this is correct
Event Hubs with checkpointing can achieve exactly-once.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
What to study next
Identify which AZ-204 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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FAQ
Connect to and consume Azure services and third-party services — This question tests Connect to and consume Azure services and third-party services — Read the scenario before looking for a memorised answer..
The correct answer is: Azure Service Bus — Azure Service Bus queues support message sessions and duplicate detection to ensure exactly-once processing. Azure Event Hubs with consumer groups and checkpointing can also achieve exactly-once semantics when combined with idempotent processing. Option A is correct because Service Bus provides duplicate detection. Option B is correct because Event Hubs with checkpointing can achieve exactly-once. Option C is incorrect because Azure Storage Queues do not guarantee exactly-once. Option D is incorrect because Event Grid offers at-least-once delivery. Option E is incorrect because Azure Cache for Redis is not a messaging service.
Identify which AZ-204 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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. You are building a solution that processes orders from multiple regions. Orders must be processed in the order they are received, but processing can take up to 5 minutes. You need to ensure exactly-once processing and minimize latency. Which Azure service and configuration should you use?
hardWhy A: Service Bus Queues with sessions provide FIFO ordering and duplicate detection. Option A is wrong because default queues don't guarantee order. Option C is wrong because Event Hubs is for streaming, not ordered queues. Option D is wrong because Storage Queues don't guarantee FIFO.
Last reviewed: Jun 20, 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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