AWS Application Load Balancer introduces Certificate Authority advertisement to simplify client behavior while using Mutual TLS

Application Load balancer (ALB) now supports advertise Certificate Authority (CA) subject name stored in its associated Trust Store to simplify the certificate selection experience. By enabling this feature, the ALB will send a list of CA subject names to clients attempting to connect to the load balancer. Clients can use this list to identify which of their certificates will be accepted by the ALB, which reduces connection errors during mutual authentication.

You can optionally configure the Advertise CA subject name feature using AWS APIs, AWS CLI, or the AWS Management Console. This feature is available for ALBs in all commercial AWS Regions, the AWS GovCloud (US) Regions and China Regions. To learn more, refer to the ALB documentation.