Exam AWS Certified Solutions Architect - Professional SAP-C02 topic 1 question 24 discussion

Logical answer : Non http port like TCP should hint to NLB immediately.(ALB does not fit here) Sharing IP address of EC2 is not apt whether it is from individual EC2 instances or those from ECS cluster.this eliminates A,B.D, infact the NLB's address which stays in front of / associates to ec2 instances need to be shared. So, only solution is C

A more appropriate solution would be option C. Create an Amazon EC2 instances for the service. Create one Elastic IP address for each Availability Zone. Create a Network Load Balancer (NLB) and expose the assigned TCP port. Assign the Elastic IP addresses to the NLB for each Availability Zone. Create a target group and register the EC2 instances with the NLB. Create a new A (alias) record set named my.service.com, and assign the NLB DNS name to the record set. As it uses the NLB as the resource in the A-record, traffic will be routed through the NLB, and it will automatically route the traffic to the healthy instances based on the health checks and also it provides the fixed address assignments as the other companies can add the NLB's Elastic IP addresses to their allow lists.

keywords: 'TCP', 'fixed address', 'regional' = NLB

By choosing Option C, the company can meet the requirements of high availability, redundancy across Availability Zones, accessibility through a DNS name (my.service.com), and fixed IP address assignments that can be added to allow lists by other companies. Option A is not suitable because it involves creating Elastic IP addresses for each EC2 instance, which can become difficult to manage and does not provide the desired DNS name accessibility. Option B is not appropriate because it uses an Amazon ECS cluster with public IP addresses, which may not provide the desired fixed IP addresses for allow listing by other companies. Option D is not the correct choice because it uses an Application Load Balancer (ALB), which is designed for HTTP/HTTPS traffic and may not be the best fit for a TCP-based service. Additionally, it involves creating public IP addresses for each host in the ECS cluster, which can be complex and may not provide the desired fixed IP addresses for allow listing.

C. Create Amazon EC2 instances for the service. Create one Elastic IP address for each Availability Zone. Create a Network Load Balancer (NLB) and expose the assigned TCP port. Assign the Elastic IP addresses to the NLB for each Availability Zone. Create a target group and register the EC2 instances with the NLB. Create a new A (alias) record set named my.service.com, and assign the NLB DNS name to the record set.

Ec2+NLB

A looks ok https://docs.aws.amazon.com/AmazonElastiCache/latest/mem-ug/Strategies.html

C: NLB with elastic IPs

C is the right answer - Few key points - TCP static Port (go with NLB), IP Whitelisting required which can only be done with NLB. ALB doesn't support static IPs. And sharing Static (Elastic) IPs of instances of no use when using NLB. We need to share NLB Elsatic IPs from Multi AZs and create DNS record for NLB Domain Name to Domain entry.

https://repost.aws/knowledge-center/elb-attach-elastic-ip-to-public-nlb

Other option haven't mention multi AZ

Static IP-> NLB

I suppose C, although you can;'t do this with A record, only alias

Create one Elastic IP address for each Availability Zone.

C is the only option that talks about more than one AZ.

Create Amazon EC2 instances for the service. Create one Elastic IP address for each Availability Zone.

IP address using NLB