When to Use Amazon EC2 Spot Instances

Answer - B.

The AWS documentation mentions the following.

Spot Instances are a cost-effective choice if you can be flexible about when your applications run and if your applications can be interrupted.

For example, Spot Instances are well-suited for data analysis, batch jobs, background processing, and optional tasks.

For more information on AWS Spot Instances, please refer to the below URL:

http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-spot-instances.html

Options A, C, and D are incorrect.

Since spot instances can be terminated by Amazon depending on market prices, they cannot be guaranteed to run during a specific period of time.

It will impact the workloads especially when they are critical.

Amazon Elastic Compute Cloud (Amazon EC2) Spot instances are suitable for workloads where the availability of instances can be flexible. This makes option B the correct answer. Here's why:

When using Spot instances, customers can bid on unused EC2 instances, which can result in significant savings (up to 90% off the On-Demand prices). However, because these instances are reclaimed by AWS when the spot price exceeds the customer's bid, they are not recommended for workloads that need to run for long periods of time without interruption, such as critical applications or services.

Spot instances are ideal for workloads with flexible start and end times or that can be interrupted without any significant impact. For example, a batch processing job that can be divided into smaller tasks and run in parallel, or a workload that can automatically stop and start again without losing progress.

In contrast, Option A is not a suitable use case for Spot instances because the customer would be charged for the entire hour even if the instance is only used for a few minutes. Option C is also not a suitable use case for Spot instances because, as mentioned above, the instances may be reclaimed by AWS and stop running at any time, which could cause long-running workloads to fail.

Option D is incorrect because Spot instances do not support termination protection, which means that AWS can reclaim the instances at any time regardless of whether termination protection is enabled.

Therefore, Amazon EC2 Spot instances are most appropriate for workloads where the availability of instances can be flexible.