Application Load Balancer (ALB) and Network Load Balancer (NLB) now support registering instances as targets when addressed by Internet Protocol Version 6 (IPv6) to simplify load balancer configuration. This launch enables you to directly register instances using IPv6 addresses as targets, removing the need to track individual IP addresses. The feature also enables the use of EC2 auto scaling groups with your target groups, which provides automatic registration of targets based on the scaling needs of your application.
Source:: Amazon AWS