Traffic Dials & Health-Check-Driven Failover

Each endpoint group (typically one per Region) has a traffic dial, a percentage controlling how much of the traffic that would naturally route to that group (based on user proximity) is actually allowed through — useful for gradually shifting load during a migration or canary rollout, independent of geographic routing. Health checks run continuously against registered endpoints within each group; if enough endpoints in a group become unhealthy, Global Accelerator automatically stops routing new traffic to that group and shifts it to the next-best healthy group, without any DNS change and without waiting for a health check grace period on the client side — this reroute typically completes in well under a minute of the health check detecting the failure.