Question 18 - Top Amazon/AWS DEA-C01 Real Exam Questions [Jan 2026 Update]

Q: 18

A company currently uses a provisioned Amazon EMR cluster that includes general purpose Amazon EC2 instances. The EMR cluster uses EMR managed scaling between one to five task nodes for the company's long-running Apache Spark extract, transform, and load (ETL) job. The company runs the ETL job every day. When the company runs the ETL job, the EMR cluster quickly scales up to five nodes. The EMR cluster often reaches maximum CPU usage, but the memory usage remains under 30%. The company wants to modify the EMR cluster configuration to reduce the EMR costs to run the daily ETL job. Which solution will meet these requirements MOST cost-effectively?

Options

Correct Answer:

Explanation

The scenario describes a workload that is CPU-bound, indicated by the cluster reaching maximum CPU usage, while memory is significantly underutilized (less than 30%). General-purpose instances provide a balanced ratio of CPU and memory. The most cost-effective solution is to right-size the instances to match the workload's specific resource requirements. Compute-optimized EC2 instances (e.g., C-family) provide a higher ratio of vCPU to memory compared to general-purpose instances. By switching to compute-optimized instances, the company can get more processing power to alleviate the CPU bottleneck without paying for unneeded memory, leading to faster job completion and lower overall costs.

References

1. Amazon EC2 Documentation

Instance Types: "Compute optimized instances are ideal for compute-bound applications that benefit from high-performance processors. ... Use cases: ... batch processing workloads...". This directly supports using compute-optimized instances for the described ETL job.

Source: AWS Documentation. (n.d.). Amazon EC2 Instance Types. Amazon Web Services. Retrieved from https://aws.amazon.com/ec2/instance-types/

2. AWS Well-Architected Framework

Cost Optimization Pillar: The framework emphasizes right-sizing and selecting the most appropriate resource type. "For example

workloads that are processing-intensive can be deployed on compute-optimized instances." This principle directly applies to the scenario.

Source: AWS Well-Architected Framework. (2023

July). Cost Optimization Pillar. p. 18. Retrieved from https://docs.aws.amazon.com/wellarchitected/latest/cost-optimization-pillar/cost-optimization-pillar.pdf

3. Amazon EMR Management Guide

Hardware and networking: "For workloads that are compute-intensive

consider using an instance type from the compute-optimized family (for example

c5.4xlarge)." This provides specific guidance for EMR cluster configuration based on workload characteristics.

Source: AWS Documentation. (n.d.). Choose EC2 instance types and sizes. Amazon EMR Management Guide. Retrieved from https://docs.aws.amazon.com/emr/latest/ManagementGuide/emr-plan-instances-guidelines.html

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