A company has migrated an application from on premises to AWS. The application frontend is a static website that runs on two Amazon EC2 instances…

This solution addresses cost optimization for both the frontend and backend tiers. The frontend is a static website, which is ideally suited for hosting on Amazon S3. This serverless approach is highly available, scalable, and significantly more cost-effective than running dedicated EC2 instances and a load balancer.

For the backend, the application is fault-tolerant (running on three instances behind an ALB) and has a spiky usage pattern. Switching from On-Demand to Spot Instances for the backend EC2 instances can provide savings of up to 90%. Because the application is already designed to be resilient to the failure of a single instance, it is a perfect candidate for Spot Instances, which can be interrupted. This combination maximizes cost savings without impacting availability.

A. Changing instance families does not address the core problem of over-provisioning for a workload that is only busy for a short period.

C. AWS Elastic Beanstalk still runs on EC2 instances, and using the same instance type would not result in any cost savings.

E. Burstable (T-family) instances are not ideal for sustained peak loads like a lunchtime rush, as they can exhaust their CPU credits and be throttled, negatively affecting performance.

1. Hosting a static website using Amazon S3: AWS Documentation clearly states

"You can host a static website on Amazon S3. On a static website

individual webpages include static content... In contrast

a dynamic website relies on server-side processing... A simple and low-cost way to host a static website is to use Amazon S3."

Source: AWS S3 Developer Guide

"Hosting a static website using Amazon S3".

2. Amazon EC2 Spot Instances Best Practices: AWS documentation recommends using Spot Instances for fault-tolerant and flexible applications. "Because Spot Instances are tightly integrated with AWS services such as Auto Scaling... you can leverage Spot Instances for a variety of fault-tolerant and flexible applications. Examples include... web services..."

Source: AWS EC2 User Guide for Linux Instances

"Spot Instance requests"

Section: "Spot best practices".

3. Cost Optimization Pillar

AWS Well-Architected Framework: This whitepaper advises using the most cost-effective resources. "Use serverless architectures to remove the need for you to run and maintain servers to carry out traditional compute activities. For example

storing static assets in Amazon S3 instead of on servers."

Source: AWS Well-Architected Framework

Cost Optimization Pillar whitepaper (aws-well-architected-framework.pdf)

Page 18

Section: "Cost-effective resources".

4. Burstable performance instances: The documentation explains the CPU credit mechanism and the risk of throttling. "If your instance requires high CPU for a prolonged period

you can... pay a flat additional fee per vCPU-hour... Or

we recommend using a fixed performance instance size..." This indicates burstable instances are not suited for sustained peaks.

Source: AWS EC2 User Guide for Linux Instances

"Burstable performance instances".