AWS's scalable, highly available DNS service. It registers domains, resolves DNS, and routes traffic using policies: Simple, Weighted, Latency-based, Failover, Geolocation, Geoproximity.
On CLF-C02 this is AWS's DNS service. SAA-C03 goes deeper into routing policies for high availability and latency. Question: route 90% of traffic to version A and 10% to version B → Weighted routing.
Amazon Route 53 is a concept that can show up on the exam. Check the full guide to see it in context.