Exam AWS Certified Solutions Architect - Professional topic 1 question 138 discussion

A and C are technically correct. But in this context, A would be my answer cos the question has mentioned that he has 2 subnets in the same AZ. I think they are trying to see if you know that you can't use the two subnets in the same AZ even though they are both private

C. If the user is creating an internal ELB, he should use only private subnets.

The correct answer is C. If the user is creating an internal ELB, he should use only private subnets. Internal Load Balancers (ELBs) are designed to be used within a VPC and cannot be accessed from the public internet. Therefore, they can only be used with private subnets. In the scenario described, the organization has created two private subnets in the same AZ and created one subnet in a separate zone. If they want to create a HA system with the internal ELB, they should use all three subnets.

i think c is correct as well though A is correct.

why c is wrong?

A. ELB can support only one subnet in each availability zone.

I go with A

I finally understand the question. It is A.

You can attach at most one subnet per Availability Zone. If you select a subnet from an Availability Zone where there is already an attached subnet, this subnet replaces the currently attached subnet for the Availability Zone.

A is correct. https://docs.aws.amazon.com/elasticloadbalancing/latest/application/create-application-load-balancer.html For Availability Zones, select at least two Availability Zones from your VPC. If there is one subnet for an Availability Zone, it is selected. If there is more than one subnet for an Availability Zone, select one of the subnets. You can select only one subnet per Availability Zone.

You can attach at most one subnet per Availability Zone https://docs.aws.amazon.com/elasticloadbalancing/latest/classic/elb-create-internal-load-balancer.html

A: You can attach at most one subnet per Availability Zone. If you select a subnet from an Availability Zone where there is already an attached subnet, this subnet replaces the currently attached subnet for the Availability Zone.

which makes C most likely correct. Although, you can create an internal ELB in a public subnet, you should create it in a private subnet. otherwise you want use an internet facing ELB.

A is correct, it is the same case for internet facing ELB as well: from the ELB console, while creating an ELB: You can specify only one subnet per Availability Zone. You may also add one Elastic IP per Availability Zone if you wish to have specific addresses for your load balancer.