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Exam Question Walkthrough: AWS Certified Solutions Architect - Associate (SAA-C03)
Explore a key exam question about designing resilient architectures on AWS and understand the reasoning behind the correct answer.
Designing resilient architectures can be tricky, especially when considering region-wide outages. Candidates often struggle with the right combination of AWS services to ensure high fault tolerance. In this post, we break down a specific exam question to clarify the right choice.
The question
Your team is designing a cloud architecture that needs to be resilient against region-wide outages. What AWS service combination can provide the highest level of fault tolerance?
- A. AWS Lambda and Amazon S3
- B. Amazon RDS with Multi-AZ and Amazon Route 53
- C. Amazon SQS and Amazon EC2 Auto Scaling
- D. Amazon EBS with snapshots across multiple regions
Think before you scroll
Consider how each option addresses the need for fault tolerance. Look for services that work together to provide automatic failover and traffic routing in the event of an outage. The right choice should ensure that your application remains available even if an entire region goes down.
The answer
The correct option is B. Amazon RDS with Multi-AZ and Amazon Route 53. This combination provides a high level of fault tolerance by enabling automatic failover to a standby instance located in another Availability Zone. Amazon Route 53 complements this by routing traffic to healthy endpoints across regions.
Why the other options lose
- A. AWS Lambda and Amazon S3: While both services are reliable, they do not inherently provide the level of fault tolerance needed for region-wide outages. AWS Lambda can run without servers, and S3 offers durability, but they lack built-in failover capabilities between regions.
- C. Amazon SQS and Amazon EC2 Auto Scaling: This combination allows for decoupling components and scaling resources, but it does not address region-wide outages. If an entire region fails, Auto Scaling cannot help if the instances are all in the same area.
- D. Amazon EBS with snapshots across multiple regions: While EBS snapshots can be taken across regions for backup, they do not provide real-time failover capabilities. If a region goes down, EBS alone cannot keep the application running without additional services for traffic management and instance availability.
The concept behind it
The core principle is to combine services that offer automatic failover and traffic management across multiple regions. Amazon RDS with Multi-AZ provides a standby instance ready to take over, while Route 53 ensures users are directed to operational endpoints, thus maintaining availability even during outages.
Exam trap to remember
Always look for service combinations that provide both redundancy and routing capabilities. The two-question rule applies: if it’s about fault tolerance, think Multi-AZ and traffic routing.