CLF-C02 Cloud Technology and Services Practice Question
A company needs to provide secure, scalable file storage for thousands of concurrent users accessing the same shared file system from Linux-based EC2 instances. Which AWS service is most appropriate?
⚠ Common exam trap
Many candidates confuse Amazon EBS Multi-Attach with a true shared file system, not realizing it is limited to a small number of instances in the same AZ and requires application-level coordination for writes, making it unsuitable for thousands of concurrent users.
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 EFS
Amazon EFS (Elastic File System) is the correct choice because it provides a fully managed, scalable, and elastic NFS file system that can be concurrently accessed by thousands of Linux-based EC2 instances. It automatically scales storage capacity up and down as files are added or removed, and it supports the NFSv4.1 and NFSv4.0 protocols, making it ideal for shared file workloads on Linux.
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 EBS Multi-Attach
Why it's wrong here
EBS Multi-Attach allows a volume to be attached to multiple EC2 instances but is limited to instances in the same AZ and only supports specific instance types — not designed for thousands of concurrent users.
- ✓
Amazon EFS
Why this is correct
Amazon EFS is a fully managed, POSIX-compliant file system designed for Linux workloads that automatically scales storage capacity and throughput as files are added or accessed. It uses the NFSv4.1 protocol and can be mounted simultaneously on thousands of EC2 instances across multiple Availability Zones, eliminating the need for manual capacity planning. This elasticity and concurrency make EFS the correct choice for scenarios requiring a shared file system with a high number of concurrent Linux users.
- ✗
Amazon S3
Why it's wrong here
Amazon S3 is an object storage service that stores data as objects in buckets and is accessed over HTTP/HTTPS via REST APIs, not through a file system interface. While S3 can be used with applications that support S3 APIs or through mountable file systems like S3FS or Mountpoint for Amazon S3, it does not natively provide POSIX/NFS semantics such as file locking or in-place edits. Therefore, for an application that expects a standard file system view over NFS, S3 is unsuitable without additional abstraction layers.
- ✗
Amazon FSx for Windows File Server
Why it's wrong here
Amazon FSx for Windows File Server delivers fully managed file storage built on Windows Server, using the Server Message Block (SMB) protocol to serve Windows clients. It does not natively support NFS access for Linux instances, and its feature set, like Windows ACLs and Active Directory integration, targets Windows-centric environments. Since the workload in this scenario requires a POSIX/NFS-compliant shared file system for Linux, FSx for Windows is not the appropriate service, whereas Amazon EFS specifically provides that NFSv4.1 interface.
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.