A team keeps internal files in an Amazon S3 bucket that uses SSE-S3 for server-side encryption and has versioning enabled. The team has already copied all existing objects to a destination bucket in a different AWS account for disaster recovery. The SysOps administrator needs the simplest operational method to keep new objects in the source bucket replicated to the cross-account destination. Which approach is the most operationally efficient?

The most operationally efficient method is to use S3 Cross-Region Replication (CRR) or Same-Region Replication (SRR), configured via a replication rule. This automates the replication of new objects (and optionally existing objects) directly within S3, requiring minimal ongoing management. The destination bucket policy grants necessary permissions for the source account to replicate objects, ensuring secure cross-account replication. Using AWS Batch or a Lambda function adds unnecessary compute and orchestration overhead for a task S3 can handle natively. While functional, these methods introduce more components to manage and monitor. Running a script on an EC2 instance is a manual, less scalable, and less resilient approach compared to native S3 replication.