AWS Certified Solutions Architect – Professional — Question 190

An organization is planning to create a secure scalable application with AWS VPC and ELB. The organization has two instances already running and each instance has an ENI attached to it in addition to a primary network interface. The primary network interface and additional ENI both have an elastic IP attached to it.
If those instances are registered with ELB and the organization wants ELB to send data to a particular EIP of the instance, how can they achieve this?

Answer options

• A. The organization should ensure that the IP which is required to receive the ELB traffic is attached to a primary network interface.
• B. It is not possible to attach an instance with two ENIs with ELB as it will give an IP conflict error.
• C. The organization should ensure that the IP which is required to receive the ELB traffic is attached to an additional ENI.
• D. It is not possible to send data to a particular IP as ELB will send to any one EIP.

Correct answer: A

Explanation

The correct answer is A because ELB can only route traffic to the primary network interface of an instance. The other options are incorrect; B is wrong as ELB can handle instances with multiple ENIs, C is incorrect since it should be the primary interface, and D is misleading because ELB can target specific IPs if configured correctly.