Q67 — AWS SAA-C03 Ch.17

Question 67 of 89 | ← Chapter 17

Q1367. A company is upgrading its critical web-based application. The application is hosted on Amazon EC2 instances that are part of an Auto Scaling group behind an Application Load Balancer(ALB). The company wants to test the new configurations with a specific amount of traffic before the company begins to route all traffic to the upgraded application.How should a solutions architect design the architecture to meet these requirements?

• A. Create a new launch template. Associate the new launch template with the Auto Scaling group. Attach the Auto Scaling group to the ALB. Distribute traffic by using redirect rules.
• B. Create a new launch template. Create an additional Auto Scaling group. Associate the new launch template with the additional Auto Scaling group. Attach the additional Auto Scaling group to the ALB.Distribute traffic by using weighted target groups. ✓
• C. Create a new launch template. Create an additional Auto Scaling group. Associate the new launch template with the additional Auto Scaling group. Create an additional ALB. Attach the additional Auto Scaling group to the additional ALB. Use an Amazon Route 53 failover routing policy to route traffic.
• D. Create a new launch template. Create an additional Auto Scaling group. Associate the new launch template with the additional Auto Scaling group. Create an additional ALB. Attach the additional Auto Scaling group to the additional ALB. Use an Amazon Route 53 weighted routing policy to route traffic.

Correct Answer: B. Create a new launch template. Create an additional Auto Scaling group. Associate the new launch template with the additional Auto Scaling group. Attach the additional Auto Scaling group to the ALB.Distribute traffic by using weighted target groups.

Explanation

The correct answer is B. Create a new launch template. Create an additional Auto Scaling group. Associate the new launch template with the additional Auto Scaling group. Attach the additional Auto Scaling group to the ALB. Distribute traffic by using weighted target groups.Explanation:The company wants to test new configurations with a specific amount of traffic before fully migrating to the upgraded application. This requires a canary deployment (gradual traffic shift) or blue-green testing (partial traffic to new version).Why Option B is the Best Choice:Separate Auto Scaling Group (ASG) for the new versionAllows running the old (existing) and new (upgraded) versions simultaneously. Ensures isolation--failures in the new version do not affect the old one.Weighted Target Groups in ALBThe Application Load Balancer (ALB) can distribute traffic between multiple target groups (each representing an ASG).Weighted routing allows controlling the percentage of traffic sent to each version (e.g., 10% to new, 90% to old).Enables gradual rollout and easy rollback if issues arise.Minimal Operational OverheadNo need for additional ALBs or Route 53 configurations (simpler than Options C & D).Uses native ALB functionality for traffic splitting.Why Other Options Are Incorrect:A. Use a single Auto Scaling group with redirect rulesNo traffic control Redirect rules send all traffic to a new location (not partial). No isolation Both old and new configurations run in the same ASG (risky if new version fails).C. Use separate ALBs + Route 53 failover routingFailover routing is for disaster recovery, not gradual testing It routes traffic to a secondary endpoint only if the primary fails.Higher cost and complexity Requires managing two ALBs and Route 53 health checks.D. Use separate ALBs + Route 53 weighted routingUnnecessary complexity Route 53 weighted routing can work, but it requires DNS-level traffic splitting, which:Has TTL delays (changes take time to propagate).Is less precise than ALB-based weighted target groups.Higher cost Two ALBs increase expenses.Best Architecture for Testing with Partial Traffic:Deploy the new version in a separate ASG (using a new launch template). Register both ASGs with the same ALB (as separate target groups). Use ALB weighted target groups to control traffic distribution (e.g., 10% new, 90% old). Monitor performance and gradually increase traffic to the new version. Roll back if issues occur (by adjusting weights or terminating the new ASG).Conclusion:Option B is the most efficient and scalable solution because it:Uses native ALB traffic splitting (precise and fast).Isolates the new version (reduces risk).Requires minimal changes (no additional ALBs or DNS configurations).Avoid Options A, C, and D (they either lack traffic control or introduce unnecessary complexity).Final Answer: B