A company uses Amazon EC2 instances behind an Application Load Balancer ALB to serve content...

For encryption in transit, AWS Certificate Manager ACM is the correct service because it provisions and manages TLS certificates for HTTPS connections. For encryption at rest, AWS KMS is the right service because it manages encryption keys used by services such as Amazon EBS. AWS documentation and whitepapers consistently position ACM for certificate-based transport encryption and KMS for at-rest encryption key management across AWS services. GuardDuty and Shield are security detection and DDoS protection services, not encryption services. Secrets Manager stores and rotates secrets, but it is not the service used to encrypt all application data at rest or TLS sessions in transit.

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