DEA-C01 Data Operations and Support Practice Question
A data engineer is using Amazon Kinesis Data Firehose to deliver streaming data to Amazon S3. The data is in JSON format, and the engineer needs to convert it to Parquet before storage to optimize Athena queries. The Firehose delivery stream is configured with an AWS Lambda function for record transformation. However, the transformed data is still in JSON format in S3. What is the likely cause?
⚠ Common exam trap
The trap here is believing that a Lambda transformation function can output Parquet directly, when actually Firehose's built-in format conversion must be enabled.
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 Firehose delivery stream is not configured with the 'Convert record format' option to convert JSON to Parquet using an AWS Glue table.
Kinesis Data Firehose can convert JSON to Parquet using the record format conversion feature, which relies on an AWS Glue table for schema. This option must be enabled in the delivery stream; otherwise, data remains in JSON even if a Lambda function transforms records. The Lambda function cannot perform the conversion itself, so enabling the Firehose setting is the correct fix.
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 Firehose delivery stream is not configured with the 'Convert record format' option to convert JSON to Parquet using an AWS Glue table.
Why this is correct
Kinesis Data Firehose supports record format conversion from JSON to Parquet or ORC using an AWS Glue Data Catalog table. This feature must be explicitly enabled in the delivery stream settings. If it is not configured, the data remains in its original JSON format regardless of any Lambda transformation. The engineer needs to enable this option and specify the Glue table schema.
- ✗
The Lambda function is missing the necessary IAM permissions to write Parquet files to S3.
Why it's wrong here
IAM permissions affect whether the Lambda function can write to S3, but the issue is not about permissions; the data is being written successfully but in JSON format. The Lambda function cannot produce Parquet output directly in this context. Therefore, missing permissions are not the cause of the format issue.
- ✗
The Lambda function is not correctly converting the JSON to Parquet; it must output Parquet-formatted records.
Why it's wrong here
AWS Lambda functions used with Kinesis Data Firehose for record transformation must return data in the same format as the input, typically JSON, and cannot perform format conversion to Parquet. The transformation is limited to modifying records, not changing the serialization format. Therefore, the Lambda function cannot directly output Parquet; Firehose handles format conversion separately.
- ✗
The S3 bucket is configured with an S3 Lifecycle policy that converts objects to Parquet after a certain period.
Why it's wrong here
S3 Lifecycle policies can transition objects between storage classes or expire them, but they cannot convert object formats. There is no S3 feature that automatically converts JSON to Parquet. This is a misconception; format conversion must be handled by the ingestion service or an ETL process, not by S3 Lifecycle rules.
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 |
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
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.