A company runs a self-managed DNS solution on three Amazon EC2 instances behind a Network Load Balancer (NLB) in us-west-2. Most users are in the United States and Europe. The company added three EC2 instances and a new NLB in eu-west-1. Which solution can route traffic to all EC2 instances across both Regions?

AWS Global Accelerator is designed for exactly this scenario: routing traffic to multiple endpoints across different AWS Regions, improving performance by directing users to the closest healthy endpoint. By creating a standard accelerator and adding the NLBs in us-west-2 and eu-west-1 as endpoints, Global Accelerator provides static Anycast IP addresses that direct user traffic to the optimal AWS edge location, then over the AWS global network to the nearest healthy NLB. The other options are less suitable: Route 53 geolocation routing with CloudFront would route to one NLB based on geographic location, but CloudFront is primarily for caching content, not for load balancing live DNS services across regions. Attaching EIPs to EC2 instances and using Route 53 geolocation would bypass the NLBs, losing their load balancing and health checking benefits, and is not a scalable solution. Replacing NLBs with ALBs and using Route 53 latency routing with CloudFront would add unnecessary complexity and cost, and CloudFront is still not the primary tool for this type of global traffic management.