SAP-C02 Design for New Solutions Practice Question
A company is designing a new application on AWS that requires a highly available and fault-tolerant architecture. Which TWO design principles should they follow?
⚠ Common exam trap
Many exam-takers confuse data backup strategies (like EBS snapshots) with high availability design, or they mistakenly believe that a single large instance or a single-region storage approach is sufficient for fault tolerance, ignoring the need for redundancy and automated recovery.
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
✓
Use Auto Scaling groups to automatically replace unhealthy instances.
Option A is correct because Auto Scaling groups continuously perform health checks and automatically terminate and replace unhealthy EC2 instances, which maintains capacity and self-heals the fleet without manual intervention, directly supporting fault tolerance. Option B is correct because deploying the application across multiple Availability Zones isolates it from a single-AZ failure; each AZ has independent power, cooling, and networking, so the workload remains available if one AZ goes down. Option C is not a high-availability design principle: manual daily EBS snapshots are a backup/recovery mechanism with a recovery point objective of up to 24 hours, not automatic failover. Option D does not belong because a single S3 bucket in one Region concentrates data in one geographic location and does not by itself provide cross-Region fault tolerance (though S3 is internally redundant within a Region). Option E is wrong because a single large EC2 instance is a single point of failure and cannot deliver high availability or fault tolerance.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Use Auto Scaling groups to automatically replace unhealthy instances.
Why this is correct
Auto Scaling groups continuously health-check instances and terminate then replace failures across Availability Zones, directly satisfying the fault-tolerance constraint. Combined with multi-AZ placement, this removes single points of failure without manual intervention, ensuring the application self-heals and maintains capacity during instance or zone impairment.
- ✓
Deploy application across multiple Availability Zones.
Why this is correct
Spreading instances across multiple Availability Zones ensures an application survives the failure of a single data centre, satisfying the fault-tolerance requirement. Each AZ has independent power, cooling and networking, so a zonal outage cannot take down the whole deployment. Combined with load balancing and health checks, traffic shifts automatically to healthy AZs.
- ✗
Manually create EBS snapshots every day.
Why it's wrong here
Manual daily snapshots give a recovery point of up to 24 hours and require human intervention, so they neither remove single points of failure nor meet fault tolerance. They are tempting as a cheap backup habit, but automated, multi-AZ replication and health-check-based failover are what the scenario demands.
- ✗
Store data in a single Amazon S3 bucket in one Region.
Why it's wrong here
A single bucket in one Region concentrates all data in one failure domain, so a Regional outage makes it unavailable. It is tempting because S3 itself is durable within a Region, but fault tolerance requires cross-Region replication or multi-Region access points rather than one location.
- ✗
Use a single large EC2 instance to simplify management.
Why it's wrong here
A single large EC2 instance creates a single point of failure; if the instance fails or the underlying hardware experiences an outage, the application becomes unavailable, directly violating the requirement for fault tolerance. This option is tempting because consolidating workloads onto one large instance reduces operational overhead and licensing costs, and it would be correct for a non-critical application where simplicity and cost control are prioritised over resilience.
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
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SAP-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 SAP-C02 exam.