AWS Certified SysOps Administrator – Associate (legacy) — Question 13

A web service runs on Amazon EC2 instances behind an Elastic Load Balancing (ELB) load balancer. External clients must whitelist specific public IP addresses in their firewalls to access the service.
What load balancer or ELB feature should be used for this application?

Answer options

• A. Network Load Balancer
• B. Application Load Balancer
• C. Classic Load Balancer
• D. Load balancer target groups

Correct answer: B

Explanation

The correct answer is B, Application Load Balancer, as it operates at the application layer, allowing for advanced routing and has the capability to manage IP whitelisting effectively. In contrast, a Network Load Balancer (A) is more suited for TCP traffic and doesn't offer application-level features, while Classic Load Balancer (C) lacks the modern features of the Application Load Balancer. Load balancer target groups (D) are used for routing traffic, but do not provide IP whitelisting functionality themselves.