Final answer:
The best approach to deploy and support a legacy application with specific configuration requirements would be to use an immutable server.
Step-by-step explanation:
The best approach to deploy and support a legacy application where the configuration for this application and the OS are very specific and cannot be changed would be to use an immutable server. An immutable server is a type of server that is built and deployed once, and then it cannot be modified. This ensures that the specific configuration required by the legacy application remains unchanged.
By using an immutable server, Janet can guarantee that the application and the OS will always have the exact same configuration every time it is deployed, reducing the risk of any compatibility or configuration issues that could arise from changes. This approach provides stability and consistency, making it the most suitable option in this case.