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Question 940 of 1,786

Data Ingestion and Transformation →easyMultiple ChoiceObjective-mapped

Why Athena Queries Miss the Last 30 Minutes of Data from Kinesis Firehose

This DEA-C01 practice question tests your understanding of data ingestion and transformation. 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 company is using Amazon Kinesis Data Firehose to ingest clickstream data from a website into an S3 bucket. The data is then analyzed using Amazon Athena. Recently, the company noticed that Athena queries are returning incomplete results for the last 30 minutes of data. The Firehose delivery stream is configured to buffer data for 60 seconds or 5 MB before delivering to S3. The S3 bucket has a lifecycle policy that transitions objects to Amazon S3 Glacier after 30 days. The IAM role for Firehose has permissions to write to S3 and access a CloudWatch Logs group. The engineer checks the Firehose monitoring and sees that the delivery rate is healthy, but the 'S3.Bytes' metric shows a spike in the last hour. The 'BackupToS3.Bytes' metric is zero. What is the MOST likely cause of the missing data?

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.

A
The lifecycle policy is transitioning data before Athena can query it.
Why wrong: The lifecycle policy transitions data to S3 Glacier after 30 days, but the issue is with recent 30 minutes of data. Athena queries are not affected by lifecycle policies on such short timeframes.
B
The backup is enabled and data is being sent to the backup bucket instead.
Why wrong: Backup is not enabled, as indicated by the 'BackupToS3.Bytes' metric being zero. Therefore, data is not being sent to a backup bucket.
C
The data is still being buffered in Firehose and has not yet been delivered to S3.
The data is still being buffered in Firehose. With buffer settings of 60 seconds or 5 MB, data can be held for up to 60 seconds before delivery. Athena queries only see data that has been delivered to S3, so data still in the buffer is missing from query results.
D
The IAM role for Firehose does not have permissions to write to the S3 bucket.
Why wrong: The IAM role for Firehose has permissions to write to S3, as indicated by the healthy delivery rate and the 'S3.Bytes' metric showing activity. If there were permission issues, errors would appear in CloudWatch Logs and delivery would fail.

Full breakdown with real-world context →

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 data is still being buffered in Firehose and has not yet been delivered to S3.

The data is still being buffered in Firehose and has not yet been delivered to S3. The buffer settings (60 seconds or 5 MB) mean data can be held in the buffer for up to 60 seconds before being written to S3. For the last 30 minutes, some data may still be in the buffer and not yet delivered. Athena queries only see data that has been delivered to S3. Option A (lifecycle policy) would not affect recent data. Option B (backup) is unrelated and the 'BackupToS3.Bytes' metric is zero, indicating backup is not active. Option D (IAM permissions) would cause errors, not missing data.

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.

✗
The lifecycle policy is transitioning data before Athena can query it.
Why it's wrong here
The lifecycle policy transitions data to S3 Glacier after 30 days, but the issue is with recent 30 minutes of data. Athena queries are not affected by lifecycle policies on such short timeframes.
✗
The backup is enabled and data is being sent to the backup bucket instead.
Why it's wrong here
Backup is not enabled, as indicated by the 'BackupToS3.Bytes' metric being zero. Therefore, data is not being sent to a backup bucket.
✓
The data is still being buffered in Firehose and has not yet been delivered to S3.
Why this is correct
The data is still being buffered in Firehose. With buffer settings of 60 seconds or 5 MB, data can be held for up to 60 seconds before delivery. Athena queries only see data that has been delivered to S3, so data still in the buffer is missing from query results.
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 IAM role for Firehose does not have permissions to write to the S3 bucket.
Why it's wrong here
The IAM role for Firehose has permissions to write to S3, as indicated by the healthy delivery rate and the 'S3.Bytes' metric showing activity. If there were permission issues, errors would appear in CloudWatch Logs and delivery would fail.

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.

Trap categories for this question

Command / output trap
The IAM role for Firehose has permissions to write to S3, as indicated by the healthy delivery rate and the 'S3.Bytes' metric showing activity. If there were permission issues, errors would appear in CloudWatch Logs and delivery would fail.

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.

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.

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.

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FAQ

Questions learners often ask

What does this DEA-C01 question test?

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 data is still being buffered in Firehose and has not yet been delivered to S3. — The data is still being buffered in Firehose and has not yet been delivered to S3. The buffer settings (60 seconds or 5 MB) mean data can be held in the buffer for up to 60 seconds before being written to S3. For the last 30 minutes, some data may still be in the buffer and not yet delivered. Athena queries only see data that has been delivered to S3. Option A (lifecycle policy) would not affect recent data. Option B (backup) is unrelated and the 'BackupToS3.Bytes' metric is zero, indicating backup is not active. Option D (IAM permissions) would cause errors, not missing data.

What should I do if I get this DEA-C01 question wrong?

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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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.