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Question 259 of 1,755

Data Engineering →easyMultiple ChoiceObjective-mapped

MLS-C01 Data Engineering Practice Question

This MLS-C01 practice question tests your understanding of data engineering. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 needs to transfer 50 TB of data from an on-premises HDFS cluster to Amazon S3. The data must be encrypted in transit and at rest. The on-premises network has a 1 Gbps connection to AWS. The transfer must complete within 5 days. Which solution is MOST cost-effective and meets the requirements?

A
Use S3 Transfer Acceleration to upload the data directly from HDFS to S3.
Why wrong: Transfer Acceleration is for public internet, not for HDFS.
B
Use AWS DataSync with a DataSync agent installed on-premises to transfer the data to S3.
DataSync can transfer over network with encryption and is optimized for speed.
C
Order an AWS Snowball Edge device and copy the data to it, then ship it back.
Why wrong: Snowball is cost-effective for large volumes but not necessary when network can handle it in 5 days.
D
Use AWS Glue to read from HDFS and write to S3 in a continuous ETL job.
Why wrong: Glue does not directly read from HDFS without a connector and is not optimized for bulk transfer.

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

✓

Use AWS DataSync with a DataSync agent installed on-premises to transfer the data to S3.

The correct answer is B (AWS DataSync). With a 1 Gbps connection, the maximum theoretical transfer in 5 days is about 54 TB (1 Gbps = 0.125 GB/s, 0.125 * 86400 * 5 = 54000 GB = 54 TB), so network transfer is feasible within the time limit. AWS DataSync uses a DataSync agent installed on-premises to transfer data from HDFS to S3, encrypting data in transit (TLS) and at rest (S3 server-side encryption). This is the most cost-effective solution because it avoids the hardware and shipping costs of Snowball Edge (option C). Option A (S3 Transfer Acceleration) does not directly integrate with HDFS and is designed for speeding up uploads over public internet, not for encrypting data from HDFS. Option D (AWS Glue) is an ETL service, not a data transfer solution, and would require additional infrastructure and complexity.

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.

✗
Use S3 Transfer Acceleration to upload the data directly from HDFS to S3.
Why it's wrong here
Transfer Acceleration is for public internet, not for HDFS.
✓
Use AWS DataSync with a DataSync agent installed on-premises to transfer the data to S3.
Why this is correct
DataSync can transfer over network with encryption and is optimized for speed.
Related concept
Read the scenario before looking for a memorised answer.
✗
Order an AWS Snowball Edge device and copy the data to it, then ship it back.
Why it's wrong here
Snowball is cost-effective for large volumes but not necessary when network can handle it in 5 days.
✗
Use AWS Glue to read from HDFS and write to S3 in a continuous ETL job.
Why it's wrong here
Glue does not directly read from HDFS without a connector and is not optimized for bulk transfer.

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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.

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 MLS-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 MLS-C01 question test?

Data Engineering — This question tests Data Engineering — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Use AWS DataSync with a DataSync agent installed on-premises to transfer the data to S3. — The correct answer is B (AWS DataSync). With a 1 Gbps connection, the maximum theoretical transfer in 5 days is about 54 TB (1 Gbps = 0.125 GB/s, 0.125 * 86400 * 5 = 54000 GB = 54 TB), so network transfer is feasible within the time limit. AWS DataSync uses a DataSync agent installed on-premises to transfer data from HDFS to S3, encrypting data in transit (TLS) and at rest (S3 server-side encryption). This is the most cost-effective solution because it avoids the hardware and shipping costs of Snowball Edge (option C). Option A (S3 Transfer Acceleration) does not directly integrate with HDFS and is designed for speeding up uploads over public internet, not for encrypting data from HDFS. Option D (AWS Glue) is an ETL service, not a data transfer solution, and would require additional infrastructure and complexity.

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

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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This MLS-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 MLS-C01 exam.