The answer is Amazon EventBridge, SQS FIFO, and Lambda. This combination achieves exactly-once processing by using EventBridge to ingest and filter events from multiple sources, then routing them to an SQS FIFO queue, which guarantees message ordering and deduplication based on a unique message ID. Lambda functions then poll the FIFO queue one message at a time, processing each event idempotently—meaning even if a retry occurs, the same event produces the same result, eliminating duplicates. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this pattern tests your understanding of how FIFO queues enforce strict ordering and deduplication, while EventBridge handles complex routing rules. A common trap is choosing SQS standard queues, which can deliver duplicates, or assuming Lambda alone provides exactly-once semantics. Memory tip: think “FIFO for order and dedup, EventBridge for routing, Lambda for idempotent execution.”
SAP-C02 Design for New Solutions Practice Question
This SAP-C02 practice question tests your understanding of design for new 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.
A company is designing a new event-driven architecture using AWS services. The system must process events from multiple sources, filter and route events to different consumers, and ensure that events are processed exactly once. Which THREE services should be used to build this architecture? (Choose three.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
AWS Lambda functions to consume events from queues and process them.
AWS Lambda functions are correct because they can be triggered by Amazon SQS FIFO queues to process messages one at a time, preserving the order and enabling idempotent processing. Lambda integrates natively with SQS, automatically scaling the number of concurrent executions based on the queue depth, which supports the exactly-once processing requirement when combined with FIFO queues.
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.
✗
Amazon Kinesis Data Firehose to deliver events to destinations.
Why it's wrong here
Firehose is for streaming data delivery, not event-driven routing.
✓
AWS Lambda functions to consume events from queues and process them.
Why this is correct
Lambda can poll SQS queues and process events.
Related concept
Read the scenario before looking for a memorised answer.
✗
AWS AppSync to provide real-time subscriptions for events.
Why it's wrong here
AppSync is for GraphQL, not for event processing architecture.
✓
Amazon SQS FIFO queues to ensure exactly-once processing.
Why this is correct
SQS FIFO guarantees exactly-once delivery and ordering.
Related concept
Read the scenario before looking for a memorised answer.
✓
Amazon EventBridge to ingest events and route them based on rules.
Why this is correct
EventBridge acts as a central event bus with filtering and routing.
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 often confuse Amazon Kinesis Data Firehose with Amazon Kinesis Data Streams, assuming Firehose supports exactly-once processing, but Firehose only provides at-least-once delivery and lacks the FIFO ordering and deduplication capabilities required for this use case.
Detailed technical explanation
How to think about this question
Amazon SQS FIFO queues use a deduplication ID and message group ID to ensure exactly-once processing and strict ordering within a group. When combined with AWS Lambda, the Lambda service polls the FIFO queue and processes messages sequentially per group, automatically deleting them only after successful execution, which prevents duplicate processing even if the function fails and retries. This pattern is commonly used in financial transaction systems where duplicate events could cause double billing or ledger inconsistencies.
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 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
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.
Design for New Solutions — This question tests Design for New Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: AWS Lambda functions to consume events from queues and process them. — AWS Lambda functions are correct because they can be triggered by Amazon SQS FIFO queues to process messages one at a time, preserving the order and enabling idempotent processing. Lambda integrates natively with SQS, automatically scaling the number of concurrent executions based on the queue depth, which supports the exactly-once processing requirement when combined with FIFO queues.
What should I do if I get this SAP-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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