What is a valid use case for a Routing Rule with an external identity provider (IdP)?

A valid use case for a Routing Rule with an external identity provider (IdP) is to provide authentication for users identified by device. This approach allows organizations to implement conditional access where different authentication methods or IdPs can be leveraged based on specific device characteristics. For example, if a user accesses the system from a corporate device, they might be routed to a more secure IdP that requires stronger authentication measures. Conversely, if a user connects from a personal device, they may be sent to a different IdP with less strict requirements. This ensures that security policies align with the risks associated with different devices, thereby enhancing overall security and user experience.

The other choices do not effectively represent typical or beneficial use cases for routing rules. Blocking users from an external IdP would defeat the purpose of enabling alternative authentication paths, while redirecting all users to a single IdP eliminates the flexibility that routing rules provide. Allowing all users to access any IdP without consideration does not optimize for security or user context, making it less aligned with best practices regarding identity and access management.