SOA-C02 EFS Standard storage class Practice Question
A company runs a critical application on Amazon EC2 instances. The application uses an NFS file system stored on an Amazon EFS file system. The SysOps administrator must ensure that the file system is highly available and can withstand an Availability Zone failure. The file system must be accessible from all Availability Zones in the region. Which configuration is required to meet these requirements?
⚠ Common exam trap
Many exam-takers confuse storage class (One Zone vs. Standard) with performance settings (provisioned throughput) or cost-saving features (lifecycle management), and overlook that the regional DNS name is essential for multi-AZ access and failover.
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
✓
Configure the EFS file system for Standard storage class and mount it using the regional DNS name.
The EFS Standard storage class replicates data across multiple Availability Zones (AZs) within a region, providing high availability and resilience against an AZ failure. Mounting the file system using the regional DNS name ensures that clients in any AZ can reach the file system via the nearest mount target, as the regional DNS name resolves to the mount target IP addresses in the local AZ. This configuration meets the requirement for the file system to be accessible from all AZs in the region while withstanding an AZ outage.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Configure the EFS file system for One Zone storage class and mount it using the file system ID.
Why it's wrong here
The One Zone storage class stores EFS data redundantly only within a single Availability Zone, so an AZ outage causes both data loss and complete file system unavailability. Mounting via the file system ID still resolves to the same single-AZ mount target, offering no cross-AZ failover. A critical application requires the Standard storage class, which replicates across multiple AZs, to withstand AZ failures.
- ✓
Configure the EFS file system for Standard storage class and mount it using the regional DNS name.
Why this is correct
The Standard storage class automatically replicates file data across multiple Availability Zones, ensuring durability even if one AZ goes down. The regional DNS name (fs-xxxx.region.efs.amazonaws.com) resolves to mount targets in every AZ where the file system is configured, allowing clients to fail over to an available mount target seamlessly. This combination provides the high availability needed for a critical application.
- ✗
Configure EFS to use provisioned throughput and mount it using a mount target IP address.
Why it's wrong here
Provisioned throughput adjusts the file system's throughput capacity independent of storage size, but it does not influence data durability or availability across zones. Using a mount target IP address bypasses DNS-based failover and pins the client to a mount target in a single AZ, so an outage in that AZ breaks connectivity. For resilience, you must rely on the regional DNS name to reach mount targets in other AZs, not a static IP.
- ✗
Enable EFS lifecycle management to move files to Infrequent Access storage class.
Why it's wrong here
Lifecycle management migrates files to the EFS Infrequent Access (IA) storage class based on a configured age threshold, lowering storage costs for cold data. It does not alter the underlying storage class redundancy: files remain on the same file system, and IA data in the Standard file system is still replicated across AZs, but for One Zone it remains single-AZ. Thus, lifecycle management is purely a cost optimization and has no effect on the file system's resilience to an AZ outage.
Visual reference
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 SOA-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 SOA-C02 exam.