- A
Amazon Elastic Block Store (EBS) with Multi-Attach enabled
Why wrong: 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.
- B
Amazon Elastic File System (EFS)
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.
- C
Amazon Simple Storage Service (S3)
Why wrong: 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.
- D
Amazon FSx for Windows File Server
Why wrong: 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.
Quick Answer
The answer is Amazon Elastic File System (EFS). EFS is the correct choice because it provides a fully managed, highly available NFS file system that automatically scales storage capacity up and down as files are added or removed, charging only for the storage used—perfectly matching the bursty, shared-file workload described. On the AWS Certified Cloud Practitioner CLF-C02 exam, this question tests your understanding of storage services for shared, concurrent access across multiple Availability Zones, often contrasting EFS with Amazon EBS (which is block storage tied to a single AZ) or Amazon S3 (which is object storage, not a mounted file system). A common trap is choosing EBS for shared storage, but remember: EBS volumes cannot be mounted by multiple EC2 instances simultaneously unless using a multi-attach configuration, which is limited. For a fully managed, auto-scaling shared file system that works across AZs, EFS is the only fit. Memory tip: "EFS = Elastic File System = Elastic scaling for shared files."
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.
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?
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.
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 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.
- ✓
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.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
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.
- ✗
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.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often 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.
Detailed technical explanation
How to think about this question
EFS uses the NFSv4.1 protocol and leverages a distributed data plane across multiple Availability Zones within a region, providing 99.999999999% (11 nines) durability. Its 'Bursting Throughput' mode allows the file system to accumulate credits during idle periods and consume them during bursty workloads, which aligns perfectly with the described pattern of large reads/writes between idle periods. Under the hood, EFS automatically grows from gigabytes to petabytes without any pre-provisioning, and the Linux kernel's NFS client handles cache coherency across multiple instances via close-to-open consistency.
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.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Questions learners often ask
What does this CLF-C02 question test?
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 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.
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.
About these practice questions
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Last reviewed: Jun 11, 2026
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.
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