CLF-C02 Cloud Technology and Services Practice Question
A company runs a database on an Amazon EC2 instance. They need block storage that persists independently from the EC2 instance — if the instance is stopped or terminated, the data must remain available. Which AWS storage service provides this?
⚠ Common exam trap
Watch out — candidates often confuse 'persistent block storage' with 'instance store' because both appear as block devices, but instance store is ephemeral and tied to the instance's physical host, while EBS is a separate network-attached volume that survives instance stops and terminations.
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 EBS
Amazon EBS (Elastic Block Store) provides persistent block-level storage volumes that can be attached to an EC2 instance. Unlike instance store, EBS volumes persist independently of the instance lifecycle — data remains intact even when the instance is stopped or terminated, as long as the volume is not deleted. This makes EBS the correct choice for the requirement of persistent, independent block storage.
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 S3
Why it's wrong here
Amazon S3 is an object storage service exposing a REST/S3 API with buckets and keys. Although it is durable and effectively unlimited, it is not a block device and cannot be formatted, mounted, or used as the root or database volume of an EC2 instance. A database engine requires low-latency random read/write block I/O, whereas S3 operations are HTTP-based object GET/PUT calls—so it fails the 'persistent block storage' requirement.
- ✗
Instance Store
Why it's wrong here
Instance Store volumes are ephemeral block devices physically attached to the host server. They offer extremely high IOPS, but their contents are lost when the instance stops, hibernates, or terminates, and data can also be lost if the underlying host fails. Because the scenario asks for data that persists independently of instance lifecycle events, ephemeral storage is the opposite of what is needed.
- ✓
Amazon EBS
Why this is correct
Amazon EBS provides durable, block-level storage volumes designed specifically for use with EC2 instances. Volumes are network-attached to a single instance, can be formatted with a filesystem, and persist independently of the instance lifecycle: stopping or terminating the instance does not delete the volume unless you explicitly set the DeleteOnTermination flag. EBS also supports features like snapshots to S3, encryption, and performance tiers such as gp3 and io2, making it the intended persistent block storage for a database.
- ✗
Amazon EFS
Why it's wrong here
Amazon EFS is a managed NFS file system that can be mounted by hundreds of EC2 instances concurrently. It is persistent and scalable, but it is file storage, not block storage; you access it over the NFSv4 protocol rather than attaching it as a raw block device. For a database that expects its own block device with predictable, dedicated I/O, EBS's per-instance block semantics are the correct fit, not EFS's shared-file semantics.
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
Courseiva writes every CLF-C02 question from scratch — 988 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
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.