AWS Certified Solutions Architect Professional SAP-C02 Practice Question

When a target is deregistered, the ALB immediately stops sending new connections to it, but any connections that are already established continue until they finish or until the deregistration delay timeout elapses. By extending the deregistration delay to cover the longest possible request or WebSocket session and enabling Terminate connections on deregistration, the load balancer allows in-flight traffic to complete gracefully and then closes any remaining connections. This prevents clients from receiving 5xx errors while the target shuts down.

Slow start only throttles traffic to new targets and does not help existing sessions. Shortening the deregistration delay makes premature termination more likely, and enabling cross-zone load balancing influences traffic distribution but does not protect in-flight requests on a draining target. Therefore, increasing the deregistration delay and turning on connection termination is the correct reliability-focused adjustment.