For an application that extensively uses microservices architecture on ECS, which load balancer type offers the best functionality?

Question

Options

• AClassic Load Balancer due to its simplicity
• BApplication Load Balancer for advanced routing capabilities
• CNetwork Load Balancer for its raw TCP performan
• DDNS Load Balancer for its cost-effectiveness

• A
  4% (1)
• B
  82% (23)
• C
  4% (1)
• D
  11% (3)

Explanation

Application Load Balancer (ALB) is purpose-built for microservices because it operates at Layer 7 (HTTP/HTTPS) and supports path-based and host-based routing - letting a single ALB direct /api/orders to one ECS service and /api/users to another, which is exactly what microservices need. It also integrates natively with ECS service discovery, supports WebSockets, and enables target group-level health checks per service.

Why the distractors are wrong:

• A (Classic LB): Legacy technology with no container-aware features; AWS itself recommends migrating away from it - "simple" doesn't mean suitable.
• C (Network LB): Operates at Layer 4 (TCP/UDP), so it's blind to HTTP routing rules; great for ultra-low latency or non-HTTP protocols, not microservice URL routing.
• D (DNS Load Balancer): Not a real AWS load balancer type - this is a fabricated distractor. Route 53 does DNS-based routing, but it's not classified as a load balancer.

Memory tip: Think ALB = Application routing = API microservices. Any time a question mentions HTTP routing, path-based rules, or containers (ECS/EKS), ALB is almost always the answer.

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