AWS Certified Advanced Networking – Specialty (ANS-C01) — Question 255

A company has 10 Amazon EC2 instances that run web server software in a production VPC. The company also has 10 web servers that run in an on-premises data center. The company has a 10 Gbps AWS Direct Connect connection between the on-premises data center and the production VPC. The data center uses the 10.100.0.0/20 CIDR block.

The company needs to implement a load balancing solution that receives HTTPS traffic from thousands of external users. The solution must distribute the traffic across the web servers on AWS and the web servers in the data center. Regardless of the location of the web servers, HTTPS requests must go to the same web server for the duration of the session.

Which solution will meet these requirements?

Answer options

• A. Deploy a Network Load Balancer (NLB) in the production VPC. Create one target group for the EC2 Instances and a second target group for the on-premises servers. Specify IP as the target type. Register the EC2 instances and the on-premises servers with the target groups. Enable connection draining on the NLB.
• B. Deploy an Application Load Balancer (ALB) in the production VPC. Create one target group for the EC2 Instances and a second target group for the on-premises servers. Specify IP as the target type. Register the EC2 instances and the on-premises servers with the target groups. Enable application-based sticky sessions on the ALB.
• C. Deploy a Network Load Balancer (NLB) in the production VPCreate one target group for the EC2 Instances and a second target group for the on-premises servers. Specify instance as the target type. Register the EC2 instances and the on-premises servers with the target groups. Enable sticky sessions on the NLB.
• D. Deploy an Application Load Balancer (ALB) in the production VPC. Create one target group for the EC2 Instances and a second target group for the on-premises servers. Specify instance as the target type. Register the EC2 instances and the on-premises servers with the target groups. Enable application-based sticky sessions on the ALB.

Correct answer: B

Explanation

The correct answer is B because an Application Load Balancer (ALB) supports application-level features like sticky sessions, which ensure that a user's session is consistently directed to the same web server. In contrast, option A uses a Network Load Balancer which does not support application-based sticky sessions, option C incorrectly specifies 'instance' as the target type, and option D also specifies 'instance' but does not provide the required application-based sticky sessions for session persistence.