Your company has a set of EC2 Instances that are placed behind an ELB. Some of the applications hosted on these instances communicate via a legacy protocol. There is a security mandate that all traffics between the client and the EC2 Instances need to be secure. How would you accomplish this?

Answer options:

A.Use an Application Load balancer and terminate the SSL connection at the ELB.B.Use a Classic Load balancer and terminate the SSL connection at the ELB.C.Use an Application Load balancer and terminate the SSL connection at the EC2 Instances.
D.Use a Classic Load balancer and terminate the SSL connection at the EC2 Instances.

Answer – D
Since there are applications that work on legacy protocols, you need to ensure that the ELB can be used at the network layer as well. Hence you should choose the Classic ELB. Since the traffic needs to be secure till the EC2 Instances, the SSL termination should occur on the EC2 Instances.
Options A and C are invalid because the Application Load Balancer does not support SSL pass-through. You need to use a Classic Load balancer.
Option B is incorrect since the encryption is required until the EC2 Instance.
For more information on HTTPS listeners for classic load balancers, please refer to the below URL
https://docs.aws.amazon.com/elasticloadbalancing/latest/classic/elb-https-load-balancers.html