Which solution meets these requirements?
Place the instances in a public subnet. Use Amazon S3 for storage. Access S3 objects by using URLs.
Place the instances in a private subnet. Use Amazon S3 for storage. Use a VPC endpoint to access S3 objects.
Use the instances with a Provisioned IOPS SSD (io2) Amazon Elastic Block Store (Amazon EBS) volume.
Use Amazon Elastic File System (Amazon EFS) Standard-Infrequent Access (Standard-IA) to store data and provide shared access to the instances.
Explanations:
The instances are required to have no internet access, but placing them in a public subnet would allow internet connectivity, violating the requirement. Additionally, using URLs to access S3 does not meet the requirement for security and persistent storage with versioning in a restricted environment.
Placing the instances in a private subnet ensures no internet access. Using a VPC endpoint to access Amazon S3 provides secure, private connectivity to S3 without requiring internet access. S3 also provides native versioning capabilities for storing and managing documents.
A Provisioned IOPS SSD (io2) Amazon EBS volume is not a shared storage solution, so it would not facilitate data sharing across instances. Additionally, EBS volumes are tied to a single EC2 instance and cannot meet the requirement for shared access.
While Amazon EFS provides shared access and would allow multiple EC2 instances to access the same data, using Standard-IA (Infrequent Access) storage is not ideal for persistent storage with versioning, as it is meant for lower-cost storage with infrequent access patterns. S3 would be more appropriate for native versioning and durability.
I have a feeling that the answer is:
Place the instances in a private subnet. Use Amazon S3 for storage. Use a VPC endpoint to access S3 objects.