MLS-C01 Data Engineering Practice Question
Which THREE of the following are best practices for optimizing performance of Amazon EMR clusters? (Choose 3)
⚠ Common exam trap
It's easy for candidates to confuse cost optimization strategies (like Spot Instances) with performance optimization, leading them to select options A or E even though the question explicitly asks for performance best practices.
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
✓
Consolidate small files into larger ones before processing
Consolidating small files into larger ones before processing on Amazon EMR reduces the overhead of the Hadoop Distributed File System (HDFS) metadata operations. Each small file consumes a block of memory in the NameNode, and processing many small files leads to excessive task launches and I/O overhead, degrading performance. Using tools like `s3-dist-cp` to combine files into fewer, larger blocks improves throughput and reduces job execution time.
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 Spot Instances for task nodes
Why it's wrong here
Again cost, not performance.
- ✓
Consolidate small files into larger ones before processing
Why this is correct
Consolidation reduces overhead and improves performance.
- ✓
Use instance fleets for heterogeneous instances
Why this is correct
Instance fleets allow flexible resource allocation.
- ✓
Enable EBS optimization on EC2 instances
Why this is correct
EBS optimization improves disk I/O performance.
- ✗
Use Spot Instances to reduce costs
Why it's wrong here
Spot instances reduce cost, not necessarily performance.
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 |
Go deeper
Related to this question
About these practice questions
Courseiva writes every MLS-C01 question from scratch — 1,672 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.