CLF-C02 Cloud Technology and Services Practice Question
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?
⚠ Common exam trap
Test-takers frequently 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.
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.
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.
When this WOULD be correct
A question requiring a block storage volume attached to multiple EC2 instances in the same Availability Zone for a clustered database (e.g., Teradata) that needs low-latency, persistent storage with concurrent writes from a limited number of instances.
- ✓
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.
- ✗
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.
When this WOULD be correct
A company needs to store and serve static website assets (e.g., images, videos) with high durability and scalability, accessed via HTTP/HTTPS. The application does not require a file system mount; instead, it uses S3 APIs or SDKs to upload/download objects.
- ✗
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.
When this WOULD be correct
A question requiring high-performance, low-latency temporary storage for data that is replicated across instances, such as a cache or scratch space, where data loss is acceptable and persistence is not needed.
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 EFSCorrect answer▾
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.
✗Amazon EBS with Multi-Attach enabledWrong answer — click to see why▾
Why this is wrong here
Amazon EBS with Multi-Attach only supports up to 16 instances in a single Availability Zone, not across multiple AZs, and is limited to io1/io2 volumes, not scalable to petabytes or fully managed for shared file access.
★ When this WOULD be the correct answer
A question requiring a block storage volume attached to multiple EC2 instances in the same Availability Zone for a clustered database (e.g., Teradata) that needs low-latency, persistent storage with concurrent writes from a limited number of instances.
Why candidates choose this
Candidates may think Multi-Attach EBS provides a shared file system, but it is a block-level attachment with AZ and instance count limitations, not a scalable, fully managed file system like EFS.
✗Amazon S3Wrong answer — click to see why▾
Why this is wrong here
Amazon S3 is an object storage service, not a shared file system. It does not provide a POSIX-compliant file system interface that multiple EC2 instances can mount simultaneously for concurrent read/write access.
★ When this WOULD be the correct answer
A company needs to store and serve static website assets (e.g., images, videos) with high durability and scalability, accessed via HTTP/HTTPS. The application does not require a file system mount; instead, it uses S3 APIs or SDKs to upload/download objects.
Why candidates choose this
Candidates may confuse S3's scalability and durability with file system capabilities, overlooking the requirement for a shared file system mount (POSIX) that EFS provides.
✗Amazon EC2 Instance StoreWrong answer — click to see why▾
Why this is wrong here
Amazon EC2 Instance Store provides temporary block-level storage that is physically attached to the host computer, but data is lost when the instance is stopped or terminated, and it cannot be shared across multiple instances or Availability Zones.
★ When this WOULD be the correct answer
A question requiring high-performance, low-latency temporary storage for data that is replicated across instances, such as a cache or scratch space, where data loss is acceptable and persistence is not needed.
Why candidates choose this
Candidates may confuse instance store with persistent storage or assume it can be shared, overlooking its ephemeral nature and lack of multi-instance access.
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
Related to this question
About these practice questions
This CLF-C02 question is part of Courseiva's 988-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. 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.
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.