The answer is a schema mismatch between the Glue table definition and the actual JSON data. Amazon Kinesis Data Firehose requires an exact field-by-field match when converting to Parquet, including data types and column order; even if the timestamp field appears in the same format, any discrepancy—such as an extra field, a missing column, or a type difference—will trigger the “Error converting to Parquet” failure. On the AWS Certified Data Engineer Associate DEA-C01 exam, this question tests your understanding that Firehose performs strict schema validation against the Glue catalog, and a common trap is assuming that a compatible format is enough when the schema must be identical. Remember, Firehose does not infer or transform schemas during Parquet conversion—it expects a perfect mirror. Memory tip: “Parquet demands perfect parity—no guessing, no gaps.”
DEA-C01 Data Ingestion and Transformation Practice Question
This DEA-C01 practice question tests your understanding of data ingestion and transformation. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 data engineer is setting up a data ingestion pipeline using Amazon Kinesis Data Firehose to deliver web server logs to Amazon S3. The logs are in JSON format and the engineer wants to convert them to Parquet format. The engineer has configured a Glue table for the schema. However, when testing, the Firehose delivery stream fails with 'Error converting to Parquet'. The engineer checks the Glue table schema and notices that it includes a column 'timestamp' of type 'string' in the format 'yyyy-MM-dd HH:mm:ss'. The logs have a 'timestamp' field in the same format. What is the MOST likely cause of the failure?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Glue table schema does not match the data schema exactly.
Option A is correct because Firehose requires the schema to match the data exactly. If the Glue table schema is not consistent with the data, conversion fails. Option B is wrong because Firehose supports Parquet conversion with Glue schema. Option C is wrong because S3 bucket permissions would cause a different error. Option D is wrong because string type is acceptable for conversion.
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.
✗
Firehose does not support Parquet conversion.
Why it's wrong here
Firehose supports Parquet conversion.
✓
The Glue table schema does not match the data schema exactly.
Why this is correct
Mismatch between schema and data causes conversion failure.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The S3 bucket lacks write permissions for Firehose.
Why it's wrong here
Write permissions would cause a different error.
✗
The 'timestamp' column must be of type 'timestamp' instead of 'string'.
Why it's wrong here
String type can be used for conversion.
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
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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.
Identify which DEA-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Data Ingestion and Transformation — This question tests Data Ingestion and Transformation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The Glue table schema does not match the data schema exactly. — Option A is correct because Firehose requires the schema to match the data exactly. If the Glue table schema is not consistent with the data, conversion fails. Option B is wrong because Firehose supports Parquet conversion with Glue schema. Option C is wrong because S3 bucket permissions would cause a different error. Option D is wrong because string type is acceptable for conversion.
What should I do if I get this DEA-C01 question wrong?
Identify which DEA-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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