Answer: Use Amazon CloudFront with a custom origin pointing to the on-premises servers.

## Explanation **Correct Answer: C - Use Amazon CloudFront with a custom origin pointing to the on-premises servers.** **Why this is the correct solution:** 1. **Immediate solution requirement**: The product is launching in a few days, so the solution needs to be quick to implement. CloudFront can be set up rapidly. 2. **Backend must remain in the United States**: The question explicitly states "The site's backend must remain in the United States." CloudFront allows you to keep your origin servers in the US while caching content at edge locations worldwide. 3. **Optimize loading times for European users**: CloudFront is a Content Delivery Network (CDN) with edge locations globally, including in Europe. It caches content closer to end-users, significantly reducing latency for European users. 4. **Dynamic website support**: CloudFront supports dynamic content through various caching strategies and can work with on-premises servers as custom origins. **Why the other options are incorrect:** **A. Launch an Amazon EC2 instance in us-east-1 and migrate the site to it.** - This doesn't solve the European latency problem. The servers would still be in the US (us-east-1 is in Virginia). - It requires migration which takes time, but an immediate solution is needed. **B. Move the website to Amazon S3. Use Cross-Region Replication between Regions.** - This is primarily for static websites, not dynamic ones. - Cross-Region Replication replicates S3 objects between regions but doesn't address the dynamic backend requirement. - The backend must remain in the US, so moving to S3 doesn't meet this requirement. **D. Use an Amazon Route 53 geoproximity routing policy pointing to on-premises servers.** - Route 53 can route users to the nearest location, but if all servers are in the US, European users will still connect to US servers. - This doesn't cache content at the edge, so users still experience transatlantic latency. - Geoproximity routing helps when you have endpoints in multiple locations, but here all servers are in the US. **Key AWS Services Used:** - **Amazon CloudFront**: Global CDN service that caches content at edge locations worldwide. - **Custom Origin**: Allows CloudFront to pull content from on-premises servers or any HTTP server. - **Edge Locations**: Points of presence worldwide that cache content closer to users. **Benefits of this solution:** - ✅ Immediate implementation - ✅ Backend remains in the US - ✅ Reduced latency for European users through edge caching - ✅ Supports dynamic websites with appropriate cache settings - ✅ No need to migrate infrastructure - ✅ Can be implemented alongside existing on-premises setup