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Fault-Tolerant Architectures: Navigating AWS Solutions
Understand how to choose the right AWS service combination for fault-tolerant architectures in the SAA-C03 exam.
Many candidates struggle with questions about fault tolerance. This particular scenario tests your understanding of how to maintain application availability during server failures. Knowing the right AWS services and their configurations is key.
The question
An organization wants to deploy a fault-tolerant architecture for its web application that can withstand server failures without any downtime. What AWS service combination should they implement?
- A. Amazon EC2 instances in an Auto Scaling group across multiple Availability Zones
- B. Amazon EC2 instances in a single Availability Zone with Elastic Load Balancing
- C. AWS Lambda functions behind an API Gateway
- D. Amazon RDS with read replicas in a single Availability Zone
Think before you scroll
Consider the requirements for fault tolerance and how different architectures handle server failures. Assess the options based on redundancy and availability across multiple Availability Zones.
The answer
The correct option is A: Amazon EC2 instances in an Auto Scaling group across multiple Availability Zones. This setup ensures that if one Availability Zone experiences an issue, the application can still run in other zones, providing the necessary fault tolerance.
Why the other options lose
- B. Amazon EC2 instances in a single Availability Zone with Elastic Load Balancing: This option does not provide redundancy across multiple Availability Zones. If the single Availability Zone goes down, the application will experience downtime.
- C. AWS Lambda functions behind an API Gateway: While Lambda provides high availability, it may not suit all web applications, especially those requiring state management. This option does not inherently address fault tolerance for traditional web applications.
- D. Amazon RDS with read replicas in a single Availability Zone: This setup offers no fault tolerance since it relies on a single Availability Zone. If that zone fails, the database becomes unavailable, impacting the application.
The concept behind it
Understanding fault tolerance involves knowing how to distribute workloads across multiple Availability Zones. When designing architectures, always ensure critical components have redundancy. This principle is essential for maintaining service availability, especially during failures.
Exam trap to remember
Remember the two-question rule: If a question asks about fault tolerance, look for options that span multiple Availability Zones. Redundancy is key.