Why is the final resolved result of domain name access not the public IP address of the EC2 instance?

The situation you're describing suggests that there are multiple layers of networking and routing in place between your domain name and the actual EC2 instance. This is common in AWS architectures for improved performance, scalability, and availability.

When you've configured AWS Global Accelerator and an Application Load Balancer (ALB), the IP addresses you're seeing are likely part of the Global Accelerator infrastructure. Global Accelerator uses a network of edge locations to route traffic to the optimal AWS endpoint, which in your case is probably the ALB.

Global Accelerator provides two static IP addresses (or alternatively, you can bring your own IP addresses) that serve as fixed entry points for your application. When clients resolve your domain name, they get these Global Accelerator IP addresses. However, behind the scenes, Global Accelerator routes the traffic through AWS's global network to the most appropriate endpoint.

The IP addresses you're seeing (like 54.4.14.23 and 44.16.27.7) are likely the addresses of AWS edge servers that are part of the Global Accelerator network. These servers receive the initial request and then intelligently route it to your ALB, which in turn forwards it to your EC2 instance.

This multi-layered approach provides several benefits:

1. Improved global performance by routing traffic through AWS's optimized network.
2. Increased availability by distributing traffic across multiple edge locations.
3. Ability to scale and change your backend infrastructure without changing the public-facing IP addresses.

It's important to note that while your EC2 instance has a public IP address, it's not directly exposed to the internet in this setup. Instead, traffic is routed through Global Accelerator and your ALB before reaching the EC2 instance, providing additional layers of abstraction and security.

If you want to confirm the exact routing, you may need to check your Global Accelerator and ALB configurations in the AWS Console to understand how traffic is being directed to your EC2 instance.
Sources
AWS Global Accelerator Now Supports EC2 Instance Endpoints
Manage the IPv4 addresses for your EC2 instances - Amazon Elastic Compute Cloud