Your company runs an application for the US market in the us-east-1 AWS region. This application uses proprietary TCP and UDP protocols on Amazon…

The application's use of proprietary TCP and UDP protocols requires a Layer 4 networking solution. An AWS Network Load Balancer (NLB), which is a type of Elastic Load Balancer (ELB), operates at the transport layer (Layer 4) and is designed to handle high-performance TCP and UDP traffic.

For global expansion with low latency, the optimal architecture involves deploying the application on EC2 instances fronted by an NLB in multiple AWS regions. Amazon Route 53 can then be configured with a latency-based routing policy. Using ALIAS records in Route 53 to point to the regional NLBs allows Route 53 to resolve DNS queries by directing users to the AWS region that offers the lowest network latency, thus fulfilling the core requirement.

A. While technically feasible, directly mapping DNS records to individual EC2 instances is less scalable and harder to manage than using a load balancer, which is the best practice.

C. Amazon CloudFront is a Content Delivery Network (CDN) optimized for caching and delivering web content over HTTP/HTTPS; it does not support arbitrary TCP or UDP protocols.

D. Amazon API Gateway is a managed service for creating and managing REST, HTTP, and WebSocket APIs. It does not support generic TCP or UDP traffic.

1. Network Load Balancer Protocol Support: AWS Documentation, User Guide for Network Load Balancers, "What is a Network Load Balancer?". This document states, "A Network Load Balancer functions at the fourth layer of the Open Systems Interconnection (OSI) model... It supports both TCP and UDP traffic, as well as TLS traffic...".

2. Route 53 Latency-Based Routing: AWS Documentation, Amazon Route 53 Developer Guide, "Choosing a routing policy", Section: "Latency-based routing". This section explains, "Use latency-based routing when you have resources in multiple AWS Regions and you want to route traffic to the region that provides the best latency."

3. Route 53 ALIAS Records for ELB: AWS Documentation, Amazon Route 53 Developer Guide, "Choosing between alias and non-alias records", Section: "Routing traffic to an ELB load balancer". This guide details the use of ALIAS records to map a domain name to an AWS resource, such as an Elastic Load Balancer.

4. API Gateway Protocol Limitations: AWS Documentation, Amazon API Gateway Developer Guide, "What is Amazon API Gateway?". The introduction clearly defines its purpose for "REST, HTTP, and WebSocket APIs," which excludes generic TCP/UDP protocols.