What is a requirement to maintain the highest level of data confidentiality for a custom object?

To maintain the highest level of data confidentiality for a custom object, it is essential to set the organization-wide defaults (OWD) to Private. This setting ensures that only the record owner and users with higher role permissions can access the records of that custom object. By restricting access in this way, it effectively safeguards sensitive data from being viewed or modified by users who do not require access for their job role.

When OWD is set to Public read/write, it allows all users to access and modify any record in that object, which significantly compromises data confidentiality. Ownership-based sharing rules and criteria-based sharing rules, while useful for granting access based on specific conditions or roles, do not provide the same level of default restriction as a Private OWD configuration. Therefore, to ensure that the data remains confidential and is shared on a need-to-know basis, setting the OWD to Private is the best approach.