DEA-C01 Data Ingestion and Transformation Practice Question
A company is ingesting streaming data from multiple sources using Amazon Kinesis Data Streams. The data is then processed by an AWS Lambda function that transforms the records and writes them to an Amazon S3 bucket. The Lambda function is failing intermittently with timeout errors. The average record size is 5 KB, and the shard count is 2. What is the MOST likely cause of the timeout errors?
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
✓
The Lambda function timeout is set too low for the processing time required.
The Lambda function is timing out, indicating that the configured timeout is insufficient for the actual processing time. Lambda has a default timeout of 3 seconds, but it can be set from 1 second to 15 minutes. If the transformation logic or S3 write operation takes longer than the configured timeout, the function will fail with a timeout error. Option B is incorrect because the Kinesis data retention period (default 24 hours) affects data availability, not Lambda execution time. Option C is incorrect because reserved concurrency controls the number of concurrent invocations and can cause throttling, not timeouts. Option D is incorrect because with an average record size of 5 KB, even the default batch size of 100 records results in only 500 KB per invocation, well below the 6 MB payload limit.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The Lambda function timeout is set too low for the processing time required.
Why this is correct
Lambda timeouts occur when execution exceeds the configured limit; intermittent failures with small 5 KB records and two shards point to processing duration, not throughput. Raising the function timeout addresses the stem's constraint directly, unlike shard or batch-size changes.
- ✗
The Kinesis data retention period is too short, causing data to be lost before processing.
Why it's wrong here
Retention governs how long records remain in the stream, not Lambda invocation duration; short retention would cause expired-iterator or data-loss errors, not timeouts. It is tempting because retention settings do affect stream reliability, and lengthening it is the right fix when consumers fall behind and records expire before being read.
- ✗
The Lambda function's reserved concurrency is set too low, causing throttling.
Why it's wrong here
Reserved concurrency throttling produces throttling errors or retries, not timeout errors; Lambda timeouts occur when processing exceeds the configured duration, such as slow S3 writes or iterator age. Low concurrency is the correct cause when invocations are rejected with TooManyRequestsException.
- ✗
The Lambda function is receiving too many records per invocation, exceeding the 6 MB payload limit.
Why it's wrong here
The 6 MB invocation payload limit concerns total batch size, but 5 KB records would need over 1,200 records per batch to breach it; intermittent timeouts instead point to per-invocation processing duration. This limit is the right diagnosis when batches contain very large records.
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 |
Go deeper
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.