CloudGuild · Blog · Cheat sheets · Lessons · Certifications
Optimizing Costs for Web Applications on AWS
Learn how to tackle a common exam question about optimizing costs for AWS web applications. Discover the right strategies and avoid pitfalls.
A common challenge for candidates is deciding how to optimize costs while maintaining application performance. The right approach can significantly impact both your exam score and real-world solutions.
The question
A company is running a web application using Amazon EC2 instances with Elastic Load Balancing (ELB) and Amazon RDS for database management. The application has varying traffic patterns, with peak usage during business hours and low usage overnight. To optimize costs while maintaining performance, what should the solutions architect recommend?
- A. Use Auto Scaling to automatically scale EC2 instances based on traffic.
- B. Switch to Reserved Instances for the EC2 instances to save costs.
- C. Implement Amazon CloudFront to cache content and reduce the load on the EC2 instances.
- D. Use AWS Lambda for all backend processing to eliminate the need for EC2 instances.
Think before you scroll
Consider the varying traffic patterns of the application. The solution must not only reduce costs but also ensure that performance remains consistent during peak hours. Each option presents a different strategy for handling costs and scalability.
The answer
The correct option is A. Use Auto Scaling to automatically scale EC2 instances based on traffic. Auto Scaling adjusts the number of EC2 instances in response to real-time traffic, optimizing costs while maintaining performance.
Why the other options lose
- B. Switch to Reserved Instances for the EC2 instances to save costs. While Reserved Instances can reduce costs, they do not provide the necessary flexibility to adjust for varying traffic patterns. They lock you into a fixed capacity that may be underutilized during off-peak hours.
- C. Implement Amazon CloudFront to cache content and reduce the load on the EC2 instances. CloudFront can improve performance by caching content, but it does not address the core issue of scaling EC2 instances according to traffic demands. It is a supplementary solution rather than a primary one.
- D. Use AWS Lambda for all backend processing to eliminate the need for EC2 instances. AWS Lambda is excellent for certain event-driven tasks but may not be suitable for all backend processing needs of the existing application. Transitioning entirely to Lambda could lead to compatibility issues and increased complexity.
The concept behind it
The principle at play here is dynamic scaling. Dynamic scaling allows resources to be adjusted based on demand, ensuring optimal performance during peak times without incurring unnecessary costs during low-usage periods. Understand this principle, and it will guide you in similar scenarios.
Exam trap to remember
Remember the two-question rule: Always analyze how the solution impacts both costs and performance. Solutions that offer flexibility in scaling are often the best choice for variable workloads.