DVA-C02 Question 48
Select 3You are developing a stateless web application on AWS that needs to handle a high volume of user requests. To ensure scalability and fault tolerance, which of the following strategies should you implement?
- A
Store user session data in Amazon ElastiCache.
- B
Store user session data on the local file system of the EC2 instances.
- C
Use Elastic Load Balancing to distribute traffic across multiple application instances.
- D
Deploy the application on multiple Availability Zones.
- E
Use Amazon EBS volumes for session storage to ensure data persistence.
Show answer and explanation
Correct answers: A, C, D
Explanation
Stateless applications do not store session information or state on their local instances. Instead, they externalize session data to services like Amazon ElastiCache or Amazon DynamoDB, enabling instances to scale independently. Elastic Load Balancing and deploying across multiple Availability Zones ensure high availability and fault tolerance, which are critical for stateless architectures. Avoid using local file systems or instance-specific storage like EBS for session data, as these approaches make the application stateful and hinder scalability.
- A. Correct.
Storing user session data in Amazon ElastiCache is a good practice for stateless applications because it keeps the session state external to the application instances, allowing instances to scale independently.
- B. Incorrect.
Storing user session data on the local file system of EC2 instances makes the application stateful, which hinders scalability and fault tolerance as the session data is tied to a specific instance.
- C. Correct.
Elastic Load Balancing helps distribute incoming traffic across multiple instances, ensuring scalability and fault tolerance for stateless applications.
- D. Correct.
Deploying the application on multiple Availability Zones improves fault tolerance and high availability, which aligns with the principles of stateless application design.
- E. Incorrect.
Using Amazon EBS volumes for session storage ties the session state to specific instances, making the application stateful and less scalable.