If some files are already present in a directory, which is converted to a shared directory under NFS, what happens to the original files that were present in that directory?

What types of application and workloads are best suited for amazon EFS?

The best feature of Amazon EFS is its ability to share files between multiple servers even if the data is present only in one server. Thus some applications include:
Media Processing and Entertainment - like Netflix,
Database Backups and Disaster Recovery,
Content Management Service - like online photo editor, text editor or video editor, etc.
Workloads should allow shared accessing, should be scalable, should be persistent.

Does cron based schedule follow UTC time or the local computer time or the instance time(time from the region where the instance exists), in DLM?

Why is a snapshot ID auto-assigned to root volume during the creation of an instance?

A snapshot ID is auto assigned to the rrot volume during instance creation because the volume ois created from an AMI.and AMI's are backed by EBS Snapshots of the root filesystem

Why is a snapshot ID auto-assigned to root volume during the creation of an instance?