- A
Use S3 PutObject with a unique object key (e.g., include a UUID) and overwrite set to false.
Correct. Using a unique object key with overwrite set to false ensures that a record is written only once; if a duplicate is attempted, it will fail, preventing multiple writes.
- B
Use DynamoDB for checkpointing to track processed records.
Why wrong: Incorrect. DynamoDB checkpointing is typically used to track processed records for at-least-once or exactly-once processing, not for at-most-once.
- C
Set the Lambda function's batch size to 100 to process records in larger batches.
Why wrong: Incorrect. Larger batch sizes increase the likelihood of partial failures and the need for retries, which is unsuitable for at-most-once.
- D
Enable function-level retries in the Lambda function for transient errors.
Why wrong: Incorrect. Enabling function-level retries would cause record reprocessing upon failure, contradicting at-most-once semantics.
- E
Set the Lambda function's batch size to 1 and the batch window to 0.
Setting batch size to 1 and batch window to 0 ensures each invocation processes a single record, but Kinesis can still retry failed records by default. This configuration minimizes the scope of reprocessing but does not by itself guarantee at-most-once semantics; it must be combined with idempotent writing (option A) to handle any retries.
DEA-C01 At-most-once processing Practice Question
This DEA-C01 practice question tests your understanding of data operations and support. 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. A key principle to apply: at-most-once processing. 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 data engineer is designing a data pipeline that ingests JSON data from Amazon Kinesis Data Streams and processes it using AWS Lambda. The Lambda function writes the processed data to an Amazon S3 bucket. The engineer needs to ensure at-most-once processing semantics. Which TWO configurations should the engineer implement? (Choose two.)
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 S3 PutObject with a unique object key (e.g., include a UUID) and overwrite set to false.
To achieve at-most-once processing semantics, the correct configurations are A and E. Option A ensures idempotency by using a unique object key (e.g., UUID) with overwrite set to false, so duplicate writes to S3 are prevented. Option E reduces the batch size to 1 and batch window to 0, minimizing the risk of reprocessing records and allowing idempotency from option A to handle any retries. Options B, C, and D are incorrect: B uses DynamoDB checkpointing for at-least-once, C increases batch size which can lead to partial failures, and D enables retries that violate at-most-once semantics.
Key principle: At-most-once processing
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 S3 PutObject with a unique object key (e.g., include a UUID) and overwrite set to false.
Why this is correct
Correct. Using a unique object key with overwrite set to false ensures that a record is written only once; if a duplicate is attempted, it will fail, preventing multiple writes.
Related concept
At-most-once processing
- ✗
Use DynamoDB for checkpointing to track processed records.
Why it's wrong here
Incorrect. DynamoDB checkpointing is typically used to track processed records for at-least-once or exactly-once processing, not for at-most-once.
- ✗
Set the Lambda function's batch size to 100 to process records in larger batches.
Why it's wrong here
Incorrect. Larger batch sizes increase the likelihood of partial failures and the need for retries, which is unsuitable for at-most-once.
- ✗
Enable function-level retries in the Lambda function for transient errors.
Why it's wrong here
Incorrect. Enabling function-level retries would cause record reprocessing upon failure, contradicting at-most-once semantics.
- ✓
Set the Lambda function's batch size to 1 and the batch window to 0.
Why this is correct
Setting batch size to 1 and batch window to 0 ensures each invocation processes a single record, but Kinesis can still retry failed records by default. This configuration minimizes the scope of reprocessing but does not by itself guarantee at-most-once semantics; it must be combined with idempotent writing (option A) to handle any retries.
Related concept
At-most-once processing
Common exam traps
Common exam trap: answer the scenario, not the keyword
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
How to think about this question
Treat this as a scenario question. Identify the problem, the constraint, and the best action. Then compare each option against those facts.
KKey Concepts to Remember
- At-most-once processing
- Unique object keys in S3
- Kinesis Lambda event source mapping
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
At-most-once processing
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.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
What to study next
Got this wrong? Here's your next step.
Review at-most-once processing, then practise related DEA-C01 questions on the same topic to reinforce the concept.
- →
Data Operations and Support — study guide chapter
Learn the concepts, then practise the questions
- →
Data Operations and Support practice questions
Targeted practice on this topic area only
- →
All DEA-C01 questions
1,786 questions across all exam domains
- →
AWS Certified Data Engineer Associate DEA-C01 study guide
Full concept coverage aligned to exam objectives
- →
DEA-C01 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related DEA-C01 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Data Ingestion and Transformation practice questions
Practise DEA-C01 questions linked to Data Ingestion and Transformation.
Data Operations and Support practice questions
Practise DEA-C01 questions linked to Data Operations and Support.
Data Security and Governance practice questions
Practise DEA-C01 questions linked to Data Security and Governance.
Data Store Management practice questions
Practise DEA-C01 questions linked to Data Store Management.
DEA-C01 fundamentals practice questions
Practise DEA-C01 questions linked to DEA-C01 fundamentals.
DEA-C01 scenario practice questions
Practise DEA-C01 questions linked to DEA-C01 scenario.
DEA-C01 troubleshooting practice questions
Practise DEA-C01 questions linked to DEA-C01 troubleshooting.
Practice this exam
Start a free DEA-C01 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this DEA-C01 question test?
Data Operations and Support — This question tests Data Operations and Support — At-most-once processing.
What is the correct answer to this question?
The correct answer is: Use S3 PutObject with a unique object key (e.g., include a UUID) and overwrite set to false. — To achieve at-most-once processing semantics, the correct configurations are A and E. Option A ensures idempotency by using a unique object key (e.g., UUID) with overwrite set to false, so duplicate writes to S3 are prevented. Option E reduces the batch size to 1 and batch window to 0, minimizing the risk of reprocessing records and allowing idempotency from option A to handle any retries. Options B, C, and D are incorrect: B uses DynamoDB checkpointing for at-least-once, C increases batch size which can lead to partial failures, and D enables retries that violate at-most-once semantics.
What should I do if I get this DEA-C01 question wrong?
Review at-most-once processing, then practise related DEA-C01 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
At-most-once processing
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 →
Keep practising
More DEA-C01 practice questions
- A data pipeline uses Kinesis Data Firehose to deliver streaming data to an S3 bucket. The data volume spikes occasionall…
- An e-commerce company uses AWS Glue to run ETL jobs that transform clickstream data from Amazon S3. The job reads Parque…
- A data engineering team uses Amazon Kinesis Data Analytics for Apache Flink to process streaming data. They notice that…
- A company uses AWS Glue to process streaming data from Amazon Kinesis Data Streams. The job reads JSON records and write…
- A data engineer applies the above bucket policy to an S3 bucket containing sensitive data. The goal is to allow only enc…
- A company uses AWS Glue to catalog data in Amazon S3. The security team requires that all sensitive data be identified a…
Last reviewed: Jun 20, 2026
This DEA-C01 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 DEA-C01 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.