You use an application load balancer to distribute traffic to your backend servers hosted on EC2. As the application serves two domain names, you have applied for two certificates in AWS Certificate Manager.
Now you want to install both certificates in the application load balancer. You are sure that the clients support Server Name Indication (SNI).
How would you configure the certificates on the application load balancer in the most cost-efficient way?

Answer options:

A.Create two HTTPS listeners in the application load balancer and install a certificate for each listener. Enable the SNI support for both listeners.
B.Add both certificates to the application load balancer listener as it supports multiple TLS certificates using SNI.
C.Create two application load balancers, and each balancer has an HTTPS listener. Install a certificate to a listener.
D.Configure a target group in the load balancer’s listener and add two certificates to the target group. Enable the SNI support for the target group.

Answer: B
Option A is incorrect because you cannot create two HTTPS listeners who listen to the same port in the application load balancer.
Option B is CORRECT because multiple certificates can be installed on the HTTPS listener. The application load balancer supports SNI, and it can choose a certificate for a client automatically.
Option C is incorrect because you do not need to create two application load balancers for this scenario as it would not be the most cost-efficient solution.
Option D is incorrect because certificates should be installed on the listener rather than the target group. 
Reference:
https://aws.amazon.com/blogs/aws/new-application-load-balancer-sni/
https://aws.amazon.com/premiumsupport/knowledge-center/acm-add-domain-certificates-elb/.