- A
Increase the number of On-Demand instances in the core node group to 20.
Why wrong: This may help but does not dynamically replace lost Spot instances; also increases cost.
- B
Configure the task node group to use only Spot instances and increase the bid price to the On-Demand price.
Why wrong: Increasing bid price to On-Demand price defeats cost savings and does not prevent reclamation.
- C
Change the task node group to use only On-Demand instances.
Why wrong: Using only On-Demand would increase costs significantly.
- D
Enable EMR managed scaling to automatically add On-Demand instances when Spot instances are reclaimed.
Managed scaling dynamically adjusts the cluster capacity, adding On-Demand instances to maintain cluster stability during Spot interruptions.
Quick Answer
The answer is to enable EMR managed scaling, which automatically adds On-Demand instances when Spot instances are reclaimed. This directly addresses EMR Spot instance reliability by dynamically replacing lost capacity during the shuffle phase, preventing job failures without requiring manual intervention. Managed scaling monitors cluster demand and interruption rates, provisioning On-Demand instances only as needed to maintain cost efficiency while ensuring task completion. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of balancing cost and reliability in ephemeral environments—a common trap is assuming all Spot or all On-Demand is the fix, but managed scaling offers the adaptive middle ground. Remember the memory tip: “When Spot drops, managed scaling swaps—On-Demand fills the gaps.”
DEA-C01 Data Operations and Support Practice Question
This DEA-C01 practice question tests your understanding of data operations and support. 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 runs a data pipeline on Amazon EMR that processes terabytes of data daily. The pipeline reads from Amazon S3, performs transformations using Spark, and writes results back to S3. Recently, the data engineer noticed that the EMR cluster's spot instances are frequently reclaimed, causing job failures and delays. The cluster uses a mix of On-Demand and Spot instances. The engineer wants to minimize job interruptions while keeping costs low. The current configuration uses a single EMR cluster with a core node group of 10 On-Demand instances and a task node group of 20 Spot instances. The job failures occur during the shuffle phase when tasks on Spot instances are lost. The engineer has no control over when spot instances are reclaimed. Which action will MOST effectively reduce job failures while maintaining cost efficiency?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"minimum / minimize"Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
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
Enable EMR managed scaling to automatically add On-Demand instances when Spot instances are reclaimed.
Option B is correct because enabling managed scaling allows EMR to automatically add On-Demand instances to replace reclaimed Spot instances, ensuring capacity without manual intervention. Option A is incorrect because using all Spot instances increases risk. Option C is incorrect because using all On-Demand increases cost significantly. Option D is incorrect because increasing On-Demand count in core node group may help but does not dynamically adjust; managed scaling is more effective.
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.
- ✗
Increase the number of On-Demand instances in the core node group to 20.
Why it's wrong here
This may help but does not dynamically replace lost Spot instances; also increases cost.
- ✗
Configure the task node group to use only Spot instances and increase the bid price to the On-Demand price.
Why it's wrong here
Increasing bid price to On-Demand price defeats cost savings and does not prevent reclamation.
- ✗
Change the task node group to use only On-Demand instances.
Why it's wrong here
Using only On-Demand would increase costs significantly.
- ✓
Enable EMR managed scaling to automatically add On-Demand instances when Spot instances are reclaimed.
Why this is correct
Managed scaling dynamically adjusts the cluster capacity, adding On-Demand instances to maintain cluster stability during Spot interruptions.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
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.
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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Data Operations and Support — study guide chapter
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FAQ
Questions learners often ask
What does this DEA-C01 question test?
Data Operations and Support — This question tests Data Operations and Support — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enable EMR managed scaling to automatically add On-Demand instances when Spot instances are reclaimed. — Option B is correct because enabling managed scaling allows EMR to automatically add On-Demand instances to replace reclaimed Spot instances, ensuring capacity without manual intervention. Option A is incorrect because using all Spot instances increases risk. Option C is incorrect because using all On-Demand increases cost significantly. Option D is incorrect because increasing On-Demand count in core node group may help but does not dynamically adjust; managed scaling is more effective.
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: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 20, 2026
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.
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