Question #272

Explanation

The correct answer is A. Spot Instances. These instances allow users to bid on unused Amazon EC2 capacity at significantly lower rates compared to the other options. Given that the company wants to scale various stateless services for short-term usage, Spot Instances provide a cost-effective solution that can greatly reduce expenditures.

Here's a breakdown of why each option is evaluated:

- A. Spot Instances: Ideal for non-urgent workloads that can handle interruptions. They allow significant savings compared to other instance types, making them the most cost-efficient choice for short-term scaling of stateless applications that can tolerate instance termination.

- B. On-Demand Instances: Although flexible and billed per hour, they can be more expensive than Spot Instances. They are best for applications with unpredictable workloads that require a consistent level of uptime without the risk of being terminated, but for a cost-sensitive solution focusing on short-term scaling, Spot Instances are preferred.

- C. Reserved Instances: These are most economical when used for long-term commitments (1 to 3 years) and are not suitable for short-term service needs. Users pay for the capacity that they reserve, whether they use it or not, which contradicts the needs presented in the question.

- D. Dedicated Hosts: These provide a physical server dedicated to your use, which can be beneficial for certain licensing or regulatory requirements, but they are the least cost-efficient for short-term usage scenarios compared to Spot Instances.

In summary, for scalable, short-term stateless service requirements, Spot Instances offer the best balance of cost and availability.

Related key knowledge includes understanding EC2 pricing models (Spot vs. On-Demand vs. Reserved vs. Dedicated) and their best-use cases.

Answer

The correct answer is: A