- A
Enable S3 event notifications with a suffix filter.
Why wrong: A suffix filter only reduces the types of objects that trigger events, but does not prevent duplicate events for the same object.
- B
Use an SQS queue to decouple S3 events.
Why wrong: While an SQS queue can buffer events, it does not guarantee deduplication. Standard queues still deliver at-least-once, and FIFO queues would require a deduplication ID but still may deliver duplicates if the ID is the same.
- C
Implement a DynamoDB table to track processed objects.
Correct. Storing processed object keys (e.g., with a condition check before writing) enables the Lambda function to detect duplicates and skip reprocessing, ensuring idempotency.
- D
Increase the Lambda function's timeout.
Why wrong: Increasing the timeout does not affect invocation frequency. Duplicate invocations will still occur.
DVA-C02 Development with AWS Services Practice Question
This DVA-C02 practice question tests your understanding of development with aws services. 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.
A developer is building a serverless application that processes user-submitted images. The images are uploaded to an S3 bucket, which triggers an AWS Lambda function that creates a thumbnail and stores it in another S3 bucket. The developer notices that sometimes the Lambda function is invoked multiple times for a single image upload. What should the developer configure to ensure idempotent processing?
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
Implement a DynamoDB table to track processed objects.
Option C is correct because S3 event notifications can occasionally deliver duplicate events (at-least-once semantics). By storing the unique object key (or ETag) in a DynamoDB table with a TTL, the Lambda function can check if the object has already been processed and skip duplicate invocations, ensuring idempotent processing.
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.
- ✗
Enable S3 event notifications with a suffix filter.
Why it's wrong here
A suffix filter only reduces the types of objects that trigger events, but does not prevent duplicate events for the same object.
- ✗
Use an SQS queue to decouple S3 events.
Why it's wrong here
While an SQS queue can buffer events, it does not guarantee deduplication. Standard queues still deliver at-least-once, and FIFO queues would require a deduplication ID but still may deliver duplicates if the ID is the same.
- ✓
Implement a DynamoDB table to track processed objects.
Why this is correct
Correct. Storing processed object keys (e.g., with a condition check before writing) enables the Lambda function to detect duplicates and skip reprocessing, ensuring idempotency.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Increase the Lambda function's timeout.
Why it's wrong here
Increasing the timeout does not affect invocation frequency. Duplicate invocations will still occur.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume SQS or filters guarantee exactly-once delivery, but AWS services like S3 and SQS both use at-least-once semantics, so idempotency must be implemented at the consumer level.
Detailed technical explanation
How to think about this question
S3 event notifications are designed with at-least-once delivery, meaning the same event can be sent multiple times due to retries or internal replication. DynamoDB conditional writes (e.g., 'attribute_not_exists') allow the Lambda function to atomically check and record processed objects, preventing duplicate thumbnail creation. A TTL on the DynamoDB item can automatically clean up old entries to manage storage costs.
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.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this DVA-C02 question test?
Development with AWS Services — This question tests Development with AWS Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Implement a DynamoDB table to track processed objects. — Option C is correct because S3 event notifications can occasionally deliver duplicate events (at-least-once semantics). By storing the unique object key (or ETag) in a DynamoDB table with a TTL, the Lambda function can check if the object has already been processed and skip duplicate invocations, ensuring idempotent processing.
What should I do if I get this DVA-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.
About these practice questions
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Last reviewed: Jun 11, 2026
This DVA-C02 practice question is part of Courseiva's free Amazon Web Services 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 DVA-C02 exam.
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