DEA-C01 Data Operations and Support Practice Question
A data engineer is using Amazon EMR to process large datasets. The cluster uses a mix of Spot Instances and On-Demand Instances. The engineer wants to reduce costs while ensuring the job can complete even if Spot Instances are reclaimed. Which TWO actions should the engineer take? (Choose two.)
⚠ Common exam trap
DEA-C01 often tests the core-vs-task node distinction, and candidates who put Spot on core nodes to save money ignore that core nodes hold HDFS data, making the job vulnerable to reclamation.
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 Instance Fleets to use multiple instance types for Spot Instances.
Option A is correct because EMR Instance Fleets let you specify multiple instance types and subnets for Spot capacity, so if one Spot pool is reclaimed or unavailable, EMR can provision from another pool, improving the chance the job finishes despite Spot interruptions. Option E is correct because task nodes perform only data-processing work and hold no HDFS data, so placing them in a Spot-based task instance group lets you capture Spot savings while core nodes (which store HDFS data) remain protected and the job can still complete if task Spot capacity is reclaimed. Option B is wrong because using only On-Demand Instances eliminates Spot savings and does not address cost reduction. Option C is wrong because core nodes hold HDFS data; using Spot for core nodes risks data loss and job failure when Spot capacity is reclaimed. Option D is wrong because termination protection only prevents accidental cluster termination and does not help the job survive Spot reclamation or reduce costs.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Enable Instance Fleets to use multiple instance types for Spot Instances.
Why this is correct
Instance Fleets let EMR select from many Spot instance types and availability zones, so a reclamation on one pool is absorbed by others. This reduces Spot interruption risk while the job continues, complementing On-Demand capacity.
- ✗
Use only On-Demand Instances for all nodes.
Why it's wrong here
Using only On-Demand Instances removes Spot reclamation risk, but it also eliminates the cost saving the scenario explicitly requires. On-Demand suits workloads with no interruption tolerance, such as stateful streaming jobs or strict SLAs. Here, the engineer needs both cost reduction and completion guarantees, which task-node Spot with core-node On-Demand provides.
- ✗
Use Spot Instances for core nodes to reduce cost.
Why it's wrong here
Spot Instances on core nodes risk losing HDFS data and shuffling capacity when reclaimed, so the job cannot reliably complete. Spot suits task nodes, which hold no data and can be replaced, making them the cost-saving target here.
- ✗
Enable termination protection for the cluster.
Why it's wrong here
Termination protection only blocks accidental API deletion of the cluster; it cannot prevent AWS reclaiming Spot capacity, so it does nothing for job completion. It is tempting because it guards long-running clusters against human error, and would be correct where an operator must be stopped from terminating a cluster mid-job.
- ✓
Use a task instance group with Spot Instances for non-critical processing tasks.
Why this is correct
Placing Spot Instances only in a task instance group isolates them from core and master nodes, so reclamation cannot terminate the cluster or lose HDFS data. Non-critical processing continues on cheaper capacity while On-Demand core nodes preserve job completion.
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Variation 1. A company uses Amazon EMR to run Spark jobs on a transient cluster. The jobs process data from S3 and write results back to S3. The team wants to reduce costs by optimizing the cluster. Which action should the team take?
easy- ✓ A.Use Spot Instances for the task nodes.
- B.Increase the number of core nodes and use larger instance types.
- C.Enable EMRFS consistent view.
- D.Terminate the cluster after each job and manually restart it for the next job.
Why A: Using Spot Instances for task nodes in a transient EMR cluster significantly reduces compute costs because Spot Instances are spare AWS EC2 capacity offered at up to 90% discount compared to On-Demand. Since transient clusters are terminated after job completion, the risk of Spot Instance interruptions is mitigated—the job can simply be retried on a new cluster if needed. This directly addresses the cost optimization goal without sacrificing job functionality.
JA
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.