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Exam Question Walkthrough: Distributing Traffic Across EC2 Instances
Learn how to tackle a question on distributing traffic for high availability in AWS. Understand the right choice and why others fail.
Designing a highly available web application is critical for many AWS Certified Solutions Architect - Associate candidates. Questions regarding service selection for traffic distribution can trip people up. Let's clarify the right choice and why it matters.
The question
A company is designing a highly available web application that uses Amazon EC2 instances in multiple Availability Zones. The application needs to ensure that users can access the website even if one Availability Zone goes down. Which AWS service should the company implement to distribute traffic across the EC2 instances in different Availability Zones?
A. Amazon Route 53
B. Amazon CloudFront
C. Elastic Load Balancing
D. AWS Global Accelerator
Think before you scroll
When analyzing this question, focus on the core requirement: distributing traffic across EC2 instances in multiple Availability Zones for high availability. Understand the roles of each service to make an informed decision.
The answer
The correct option is C. Elastic Load Balancing. This service automatically distributes incoming application traffic across multiple targets, such as EC2 instances, ensuring that if one Availability Zone fails, the application remains accessible through instances in other zones.
Why the other options lose
- A. Amazon Route 53: This is primarily a DNS service. While it can route traffic based on health checks, it does not directly manage traffic distribution to EC2 instances like a load balancer does.
- B. Amazon CloudFront: This is a content delivery network (CDN) designed to cache content at edge locations for faster access. It doesn't distribute traffic among EC2 instances in different Availability Zones, which is the requirement here.
- D. AWS Global Accelerator: This service improves access to applications by directing traffic to optimal endpoints. However, it does not provide load balancing capabilities necessary to distribute traffic across multiple EC2 instances in different Availability Zones.
The concept behind it
Understanding Elastic Load Balancing is key for high availability. It not only balances traffic but also performs health checks on targets. If an EC2 instance in one Availability Zone becomes unhealthy, the load balancer automatically routes traffic to healthy instances in other zones. This principle applies to designing resilient architectures in AWS.
Exam trap to remember
Remember: Elastic Load Balancing is essential for distributing traffic across multiple resources for high availability. Focus on services that fulfill that specific role in the questions you encounter.