CLF-C02 Cloud Technology and Services Practice Question
A company runs a data analytics workload on a cluster of Amazon EC2 instances. The application requires a shared file system that can be mounted by multiple EC2 instances simultaneously. The workload is bursty: during data processing jobs, the instances write and read large datasets, but between jobs the file system is mostly idle. The company wants a fully managed, highly available, and durable file storage solution that automatically scales capacity up and down and charges only for the storage used. The solution must be accessible from EC2 instances across multiple Availability Zones in the same AWS Region. Which AWS service should the company use?
⚠ Common exam trap
Many exam-takers confuse Amazon EBS Multi-Attach (which is limited to a single AZ and requires manual capacity management) with a truly multi-AZ, auto-scaling shared file system, or they mistakenly think S3 can serve as a POSIX-compatible shared file system for EC2 instances.
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
✓
Amazon Elastic File System (EFS)
Amazon EFS is a fully managed, highly available, and durable NFS file system that automatically scales storage capacity up and down as files are added or removed, charging only for the storage used. It can be mounted by multiple EC2 instances across different Availability Zones simultaneously, making it ideal for bursty, shared-file workloads that require concurrent access and automatic scaling.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Amazon Elastic Block Store (EBS) with Multi-Attach enabled
Why it's wrong here
EBS Multi-Attach allows a single Provisioned IOPS EBS volume to be attached to multiple EC2 instances in the same Availability Zone, but it is not a fully managed file system; it is a block storage device that you must manage and format. It does not automatically scale capacity and cannot be used across Availability Zones.
When this WOULD be correct
A question where a single EC2 instance needs a block-level storage volume with low-latency, persistent storage, and the workload requires attaching the same volume to multiple instances in a single Availability Zone for a clustered database or similar application.
- ✓
Amazon Elastic File System (EFS)
Why this is correct
Amazon EFS is a fully managed NFS file system that automatically scales storage capacity as you add or remove files, and you pay only for the storage used. It provides high availability and durability by storing data across multiple Availability Zones within a Region, and can be accessed by multiple EC2 instances concurrently.
- ✗
Amazon Simple Storage Service (S3)
Why it's wrong here
Amazon S3 is object storage, not a file system. It does not provide a POSIX-compliant file system interface and cannot be directly mounted via NFS without additional tools like Amazon S3 File Gateway, which adds complexity and does not automatically scale capacity like EFS.
When this WOULD be correct
A company needs to store and retrieve large amounts of data (e.g., backups, logs, or media files) with high durability and scalability, accessed via RESTful APIs or SDKs, and wants to pay only for storage used. The workload does not require a mounted file system or low-latency file access.
- ✗
Amazon FSx for Windows File Server
Why it's wrong here
Amazon FSx for Windows File Server is a fully managed Windows file server, but it does not automatically scale storage capacity down; you provision storage upfront and can increase it, but decreasing requires manual intervention. It also uses the SMB protocol and is typically used for Windows-based workloads, not the Linux-based analytics environment implied here.
When this WOULD be correct
A company runs a Windows-based application on EC2 instances that needs a shared file system accessible via SMB protocol across multiple Availability Zones. The workload requires high availability and durability, and the company prefers a fully managed service that integrates with Active Directory.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The CLF-C02 exam frequently reuses these exact scenarios with slightly different constraints.
✓Amazon Elastic File System (EFS)Correct answer▾
Why this is correct
Amazon EFS is a fully managed NFS file system that automatically scales storage capacity as you add or remove files, and you pay only for the storage used. It provides high availability and durability by storing data across multiple Availability Zones within a Region, and can be accessed by multiple EC2 instances concurrently.
✗Amazon Elastic Block Store (EBS) with Multi-Attach enabledWrong answer — click to see why▾
Why this is wrong here
Amazon EBS Multi-Attach supports only a limited number of instances (up to 16) and is not designed for bursty, high-throughput workloads that require automatic scaling of capacity and pay-per-use pricing. EBS volumes must be provisioned in advance and do not scale down automatically.
★ When this WOULD be the correct answer
A question where a single EC2 instance needs a block-level storage volume with low-latency, persistent storage, and the workload requires attaching the same volume to multiple instances in a single Availability Zone for a clustered database or similar application.
Why candidates choose this
Candidates may think Multi-Attach EBS provides shared access like a file system, but they overlook its limitations in scalability, automatic capacity management, and cross-AZ access.
✗Amazon Simple Storage Service (S3)Wrong answer — click to see why▾
Why this is wrong here
Amazon S3 is an object storage service, not a file system. It does not provide a POSIX-compliant shared file system that can be mounted by EC2 instances, and it lacks the low-latency file access required for data analytics workloads.
★ When this WOULD be the correct answer
A company needs to store and retrieve large amounts of data (e.g., backups, logs, or media files) with high durability and scalability, accessed via RESTful APIs or SDKs, and wants to pay only for storage used. The workload does not require a mounted file system or low-latency file access.
Why candidates choose this
Candidates may confuse S3's scalability and pay-per-use pricing with the requirements of a shared file system, overlooking that S3 is object storage and cannot be mounted as a file system without additional tools like S3FS, which are not fully managed or performant for this use case.
✗Amazon FSx for Windows File ServerWrong answer — click to see why▾
Why this is wrong here
Amazon FSx for Windows File Server is designed for Windows-based applications requiring SMB protocol support, not for the Linux-based data analytics workloads typically using NFS. The question does not specify Windows or SMB requirements, making EFS the more appropriate fully managed NFS solution.
★ When this WOULD be the correct answer
A company runs a Windows-based application on EC2 instances that needs a shared file system accessible via SMB protocol across multiple Availability Zones. The workload requires high availability and durability, and the company prefers a fully managed service that integrates with Active Directory.
Why candidates choose this
Candidates may confuse FSx for Windows File Server with a general-purpose shared file system, overlooking that it is specifically for Windows workloads and SMB protocol, while the question implies a Linux/NFS environment.
Analysis generated from the official CLF-C02blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CLF-C02 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 CLF-C02 exam.