What is the maximum number of default domains allowed in an instance?

In the context of an instance, the maximum number of default domains allowed is one. This is because a default domain serves as the primary domain for the instance, providing a single source of truth for user authentication and access control. Having a single default domain simplifies management and ensures that all user identities and associated access rights are centralized, reducing complexity when managing permissions and configurations.

While it may be possible to create multiple domains within an instance for different purposes, only one can be designated as the default domain. This structure supports clarity and organization within the system, which is crucial for effective administration and security practices.

The other options suggest having unlimited, three, or five default domains, which could lead to confusion and administrative challenges. Allowing multiple default domains would complicate the management of user access and authentication, potentially leading to conflicts and inconsistency within the instance environment. Thus, maintaining a single default domain ensures streamlined operations and enhances the overall integrity of the system's user management.