Your team uses Amazon ECS to manage containers for several micro-services. To save cost, multiple ECS tasks should run at a single container instance. When a task is launched, the host port should be dynamically chosen from the container instance`s ephemeral port range. The ECS service should select a load balancer that supports dynamic mapping. Which types of load balancers are appropriate?

Answer options:

A.Application Load Balancer or Network Load Balancer.
B.Application Load Balancer only.
C.Network Load Balancer only.
D.Application Load Balancer or Classic Load Balancer.

Correct Answer – A
Option A is CORRECT because both Application Load Balancer and Network Load Balancer support dynamic mapping. You can configure the ECS service to use the load balancer, and a dynamic port will be selected for each ECS task automatically. With Dynamic mapping, multiple copies of a task can run on the same instance.
Option B and C are incorrect: Please check the below references.
Option D is incorrect because Classic Load Balancer does not support dynamic mapping. With Classic Load Balancer, you have to define the port mappings on a container instance statically.
Reference:
https://docs.aws.amazon.com/AmazonECS/latest/userguide/load-balancer-types.html.
https://aws.amazon.com/premiumsupport/knowledge-center/dynamic-port-mapping-ecs/.