The answer is Amazon EFS, the AWS storage service designed for shared file storage accessible simultaneously by multiple EC2 instances using the NFS protocol. This is correct because Amazon EFS provides a fully managed, elastic NFS file system that supports the NFSv4.1 protocol, allowing hundreds of EC2 instances to mount the same file system concurrently across multiple Availability Zones. On the AWS Certified Cloud Practitioner CLF-C02 exam, this question tests your understanding of the core storage services and their use cases—specifically distinguishing shared file storage from block storage (EBS) or object storage (S3). A common trap is confusing EBS with EFS: remember that EBS volumes can only be attached to a single EC2 instance in one Availability Zone, while EFS is designed for multi-instance, multi-AZ shared access. For a quick memory tip, think of the “F” in EFS as standing for “File” and “Federation” of instances, reinforcing that it’s the shared NFS file system for your EC2 fleet.
CLF-C02 Cloud Technology and Services Practice Question
This CLF-C02 practice question tests your understanding of cloud technology and services. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which AWS storage service is designed for shared file storage accessible simultaneously by multiple EC2 instances using the NFS protocol?
Why wrong: EBS volumes are block storage attached to a single EC2 instance at a time — they don't support simultaneous access from multiple instances natively (except EBS Multi-Attach, which has limitations).
B
Amazon S3
Why wrong: S3 is object storage accessed via HTTP API — it's not a mountable NFS file system for applications expecting a file system interface.
C
Amazon EFS
EFS is a managed NFS file system that can be mounted by multiple EC2 instances across multiple AZs simultaneously, with automatic scaling from gigabytes to petabytes.
D
Amazon FSx for Windows File Server
Why wrong: FSx for Windows provides managed Windows file shares using SMB protocol — it's designed for Windows workloads, not Linux NFS-based shared storage.
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 a fully managed, scalable NFS file system that can be mounted concurrently on multiple EC2 instances. It uses the NFSv4.1 protocol, enabling shared access across Availability Zones and instances, which is exactly what the question describes.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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
Why it's wrong here
EBS volumes are block storage attached to a single EC2 instance at a time — they don't support simultaneous access from multiple instances natively (except EBS Multi-Attach, which has limitations).
✗
Amazon S3
Why it's wrong here
S3 is object storage accessed via HTTP API — it's not a mountable NFS file system for applications expecting a file system interface.
✓
Amazon EFS
Why this is correct
EFS is a managed NFS file system that can be mounted by multiple EC2 instances across multiple AZs simultaneously, with automatic scaling from gigabytes to petabytes.
Related concept
Read the scenario before looking for a memorised answer.
✗
Amazon FSx for Windows File Server
Why it's wrong here
FSx for Windows provides managed Windows file shares using SMB protocol — it's designed for Windows workloads, not Linux NFS-based shared storage.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse EBS (block storage) with a shared file system, not realizing that EBS volumes are single-instance attached by default, while EFS is purpose-built for multi-instance NFS access.
Detailed technical explanation
How to think about this question
EFS implements a distributed, regional file system that automatically scales storage capacity up to petabytes as files are added or removed, without requiring provisioning. Under the hood, EFS uses a cluster of file servers and a metadata layer to provide strong consistency and low-latency access across multiple EC2 instances, even across different Availability Zones. A real-world scenario is a web server farm where all instances share the same content directory, ensuring consistent static assets without manual replication.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CLF-C02 question in full detail.
Cloud Technology and Services — This question tests Cloud Technology and Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Amazon EFS — Amazon EFS (Elastic File System) is a fully managed, scalable NFS file system that can be mounted concurrently on multiple EC2 instances. It uses the NFSv4.1 protocol, enabling shared access across Availability Zones and instances, which is exactly what the question describes.
What should I do if I get this CLF-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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