Question #1276
A company operates a critical application on Amazon EC2 instances that must remain operational without interruption for a minimum of three years. Which EC2 purchasing option should the company select to achieve the highest cost savings?
Reserved Instances
Spot Instances
On-Demand Instances
EC2 Fleet
Explanation
The correct answer is A. Reserved Instances. Here's why:
- Reserved Instances (RIs): Offer up to 72% discount compared to On-Demand pricing when committing to a 1- or 3-year term. Since the company requires a 3-year uninterrupted workload, RIs are the most cost-effective option.
- Spot Instances (B): These are unsuitable for critical applications because AWS can reclaim them with short notice, leading to interruptions.
- On-Demand Instances (C): No upfront cost, but the most expensive option for long-term use, making them less economical than RIs.
- EC2 Fleet (D): Manages a mix of purchasing options (Spot, On-Demand, RIs) but does not guarantee cost savings alone. Spot usage would risk interruptions, violating the requirement.
Key Points:
- Use Reserved Instances for predictable, long-term workloads to maximize savings.
- Avoid Spot Instances for critical applications requiring high availability.
- On-Demand is flexible but costly for multi-year commitments.
Answer
The correct answer is: A