DNS at Scale

Route 53 is more than just a DNS registrar. it's a global traffic management system with 100% uptime SLA.

1. Routing Policies

- **Simple:** Just maps a name to an IP.
- **Weighted:** Splits traffic (e.g., 90% to Old Version, 10% to New Version). Essential for **Canary Deployments**.
- **Latency:** Routes users to the AWS Region with the lowest latency.
- **Failover:** Automatically switches to a 'Backup' site if the primary health check fails.

2. Alias Records vs CNAME

In Route 53, always use Alias Records for AWS resources (like Load Balancers). They are free, handle IP changes automatically, and allow you to map the 'Root' domain (e.g., toolliyo.com) to a Load Balancer, which standard DNS CNAMEs cannot do.

3. Architect Insight

Q: "How do I implement 'Global' High Availability?"

Architect Answer: "Use **Multi-Region Failover**. Deploy your .NET app in two different AWS Regions (e.g., London and New York). Use Route 53 Health Checks to monitor the London endpoint. If London goes dark, Route 53 will automatically update DNS to point users to New York. This is the ultimate 'Panic Button' for enterprise apps."