What should a solutions architect recommend to meet the clients’ needs?
A Network Load Balancer with an associated Elastic IP address.
An Application Load Balancer with an associated Elastic IP address.
An A record in an Amazon Route 53 hosted zone pointing to an Elastic IP address.
An EC2 instance with a public IP address running as a proxy in front of the load balancer.
Explanations:
A Network Load Balancer (NLB) supports static IP addresses and can be associated with an Elastic IP (EIP). This provides the clients with a fixed IP address they can whitelist. NLBs are ideal for scenarios requiring static IPs for accessing services.
An Application Load Balancer (ALB) does not support Elastic IPs. ALBs are designed for HTTP/HTTPS traffic and auto-scale, but they do not offer a static IP, making it unsuitable for clients needing a fixed IP address for firewall whitelisting.
An A record in Route 53 can point to an Elastic Load Balancer (ELB), but this doesn’t guarantee a static IP address. The IPs of ELBs can change over time, so this does not satisfy the requirement for fixed IPs.
Running an EC2 instance as a proxy would work, but it adds unnecessary complexity. The instance would need to manage traffic routing, and it still requires handling the IP address whitelisting manually. This option is less efficient compared to using an NLB with an Elastic IP.
It seems to me that the answer is:
A Network Load Balancer with an associated Elastic IP address.