5.2Route 53 and DNS Routing

Amazon Route 53 controls which endpoint a domain name resolves to. Choosing the right routing policy for the requirement is the operational point.

5.2.1Routing policies

• Failover: switch to secondary on primary failure via health checks (active-passive).
• Latency/Geo: route to the lowest-latency region or by geographic location.
• Weighted: split traffic by percentage (canary/A-B test). Simple is a single record.
• Health checks: monitor endpoint health and integrate with failover, etc.

Route 53 is "DNS + health checks"; pick a routing policy by requirement. Simple is a single record (multiple values returned in no particular order); failover switches to a secondary on primary failure via health checks (active-passive); latency routes to the lowest-latency region; geolocation routes by the user’s country/region; geoproximity uses location plus a bias; weighted splits traffic by percentage (canary/A-B). For AWS resources (ALB/CloudFront/S3 website) use Alias records (work at the zone apex, no extra charge); use CNAME for external targets. The key to availability is health checks (endpoint, calculated, or CloudWatch-alarm based), integrated with failover and "drop unhealthy targets." A small TTL speeds switchover but increases queries. DNS propagates eventually, so design with TTL in mind.