- A
Amazon EBS with Multi-Attach enabled
Why wrong: Amazon EBS Multi-Attach allows a single EBS volume to be attached to up to 16 Nitro-based EC2 instances in the same Availability Zone. It does not support cross-AZ access, has limited scalability, and is not intended for petabyte-scale workloads. It is also not fully managed for scaling to petabytes.
- B
Amazon EFS
Amazon EFS provides a fully managed, elastic NFS file system that can be mounted on multiple EC2 instances across multiple Availability Zones. It scales automatically to petabytes, offers high durability, and is designed for concurrent access from thousands of instances. This matches all requirements.
- C
Amazon S3
Why wrong: Amazon S3 is an object storage service, not a file system. While it can be accessed from multiple instances, it does not provide a POSIX-compliant file system interface. Applications expecting a shared file system with standard file operations (like locking or appends) would not work directly with S3.
- D
Amazon EC2 Instance Store
Why wrong: Instance Store provides temporary block-level storage that is physically attached to the host computer. It is ephemeral (data is lost if the instance stops or terminates) and cannot be shared across multiple instances. It does not meet durability or shared access requirements.
Quick Answer
The answer is Amazon EFS, the fully managed NFS file system designed for this exact use case. Amazon EFS provides a shared file system accessible from multiple EC2 instances across Availability Zones, automatically scaling storage capacity to petabytes as data grows while maintaining high durability by replicating files across multiple AZs. On the AWS Certified Cloud Practitioner CLF-C02 exam, this scenario tests your ability to distinguish between block storage (EBS), object storage (S3), and shared file storage (EFS), with a common trap being to choose EBS volumes, which are tied to a single AZ and cannot be mounted concurrently across zones. Remember that EFS is the only AWS storage service that offers a POSIX-compliant, elastic file system for simultaneous multi-instance access. A simple memory tip: EFS stands for Elastic File System, and think “EFS = Everywhere File System” because it works across AZs, unlike EBS which is “Elastic Block Stuck” in one zone.
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 web application on multiple Amazon EC2 instances across two Availability Zones. The application processes user-uploaded documents and must store them in a shared file system that all instances can access simultaneously. The file system must be scalable to petabytes, durable, and fully managed. Which AWS service should the company use to meet these requirements?
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 is a fully managed, scalable, and durable NFS file system that can be mounted concurrently by multiple EC2 instances across different Availability Zones. It automatically scales storage capacity up to petabytes as files are added or removed, and it provides high durability by replicating data across multiple AZs within a region. This makes it the ideal choice for a shared file system that must be accessed simultaneously by all instances.
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 with Multi-Attach enabled
Why it's wrong here
Amazon EBS Multi-Attach allows a single EBS volume to be attached to up to 16 Nitro-based EC2 instances in the same Availability Zone. It does not support cross-AZ access, has limited scalability, and is not intended for petabyte-scale workloads. It is also not fully managed for scaling to petabytes.
- ✓
Amazon EFS
Why this is correct
Amazon EFS provides a fully managed, elastic NFS file system that can be mounted on multiple EC2 instances across multiple Availability Zones. It scales automatically to petabytes, offers high durability, and is designed for concurrent access from thousands of instances. This matches all requirements.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Amazon S3
Why it's wrong here
Amazon S3 is an object storage service, not a file system. While it can be accessed from multiple instances, it does not provide a POSIX-compliant file system interface. Applications expecting a shared file system with standard file operations (like locking or appends) would not work directly with S3.
- ✗
Amazon EC2 Instance Store
Why it's wrong here
Instance Store provides temporary block-level storage that is physically attached to the host computer. It is ephemeral (data is lost if the instance stops or terminates) and cannot be shared across multiple instances. It does not meet durability or shared access requirements.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Amazon S3's object storage capabilities with a shared file system, but S3 lacks POSIX file locking and mountability, making it unsuitable for simultaneous file-level access from multiple EC2 instances.
Detailed technical explanation
How to think about this question
Amazon EFS implements the NFSv4.1 protocol and uses a distributed data store that automatically replicates file data and metadata across multiple Availability Zones for high durability (99.999999999% annual durability). The file system scales performance based on the amount of data stored and the burst credit model, with throughput scaling from 50 MB/s per TB of storage in Bursting mode to provisioned throughput up to 10 GB/s. In real-world scenarios, EFS is commonly used for content management systems, web serving, and big data analytics where multiple instances need concurrent access to the same files.
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.
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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 EFS — Amazon EFS is a fully managed, scalable, and durable NFS file system that can be mounted concurrently by multiple EC2 instances across different Availability Zones. It automatically scales storage capacity up to petabytes as files are added or removed, and it provides high durability by replicating data across multiple AZs within a region. This makes it the ideal choice for a shared file system that must be accessed simultaneously by all instances.
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
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
2 more ways this is tested on CLF-C02
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company runs a web application across multiple Amazon EC2 instances that are distributed across several Availability Zones. The application needs to share a common set of configuration files and static assets that must be accessible concurrently and consistently from all instances. The company wants a fully managed, scalable file storage solution that does not require provisioning or managing underlying storage hardware. Which AWS service should the company use?
medium- ✓ A.Amazon Elastic File System (EFS)
- B.Amazon Elastic Block Store (EBS)
- C.Amazon Simple Storage Service (S3)
- D.Amazon Relational Database Service (RDS)
Why A: Amazon EFS provides a fully managed, scalable, and shared file system that can be mounted concurrently by multiple EC2 instances across different Availability Zones. It uses the NFSv4.1 protocol, ensuring consistent access to configuration files and static assets without any provisioning or management of underlying storage hardware.
Variation 2. A company runs a web application on multiple EC2 instances across multiple Availability Zones. All instances need to access and share the same file system simultaneously to read and write shared configuration files. Which AWS storage service supports simultaneous access from multiple EC2 instances?
medium- A.Amazon EBS
- B.Instance Store
- ✓ C.Amazon EFS
- D.Amazon S3
Why C: Amazon EFS is a fully managed, NFS-based file system that can be mounted concurrently by multiple EC2 instances across different Availability Zones, providing shared access for reading and writing configuration files. It uses the NFSv4.1 protocol and supports thousands of simultaneous connections, making it ideal for shared storage scenarios.
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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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