CLF-C02 Cloud Technology and Services Practice Question
Which AWS storage type provides the lowest latency storage for a single EC2 instance, with data stored on NVMe SSDs physically attached to the host computer?
⚠ Common exam trap
It's easy for candidates to confuse Amazon EBS with local storage, but EBS is network-attached and cannot match the latency of physically attached NVMe SSDs, which is the key differentiator for this question.
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
✓
EC2 Instance Store
EC2 Instance Store provides temporary block-level storage for an EC2 instance, with data stored on NVMe SSDs that are physically attached to the host computer. This direct attachment eliminates network latency, offering the lowest possible latency for a single EC2 instance compared to any network-attached storage 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 (Elastic Block Store)
Why it's wrong here
Amazon EBS provides persistent block storage volumes that are attached to an EC2 instance, but the volumes reside in a separate storage subsystem and communicate over the network, typically through the Nitro system or iSCSI. This network-attached design contributes additional latency and variability compared to a physically attached NVMe instance store, even with optimized EBS volumes. While EBS offers durability, snapshots, and detach/reattach capabilities, those benefits come at the cost of the few extra microseconds of delay that matter when the goal is the lowest possible storage latency.
- ✗
Amazon EFS (Elastic File System)
Why it's wrong here
Amazon EFS is a fully managed, POSIX-compliant network file system that must be mounted over the network and is designed for shared access across many EC2 instances. Because every read and write traverses the network fabric to reach the file system service, it introduces far higher latency than a locally attached NVMe device. Even with enhanced throughput or performance modes, EFS cannot provide the lowest possible latency for a single instance's temporary or scratch data.
- ✓
EC2 Instance Store
Why this is correct
EC2 Instance Store is physically attached to the host server, so I/O goes directly to the disk without traveling over any external network. This direct NVMe attachment provides the lowest possible latency and highest per-instance burst performance among all EC2 storage options, which is exactly why it is recommended for buffers, caches, and scratch data. However, instance store volumes are ephemeral: data is lost when the instance is stopped, terminated, or the underlying host fails, so it must not be used for durable or persistent data.
- ✗
Amazon S3
Why it's wrong here
Amazon S3 is an object storage service that holds data in buckets and is accessed only through HTTPS-based REST API calls, not as a local block device. Every object operation requires a full network round trip to an S3 endpoint, adding latency that is orders of magnitude higher than a directly attached SSD. S3 also lacks block-level addressing and filesystem semantics like seek and low-level read-modify-write operations, making it completely unsuitable when the requirement is the absolute lowest latency for temporary, high-frequency data on an EC2 instance.
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 |
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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.