Which of the following is a best practice regarding domain federations?

Creating an in-cloud Global Administrator account is a best practice regarding domain federations because it ensures that you have a reliable and secure means of administering your Okta and Office 365 environments during the federated configuration process. Having an in-cloud Global Administrator account allows for easier management of your settings and user access, especially if there's ever an issue with federation or connectivity. It acts as a backup or contingency plan, ensuring that administrative functions can continue without disruption, as it provides direct access to the Office 365 environment.

Using a dedicated in-cloud account helps mitigate risks associated with relying solely on federated accounts for administrative tasks. In scenarios where domain authentication or federation may face issues, having a Global Administrator account available in the cloud ensures that you can troubleshoot and resolve problems without needing to revert back to more complex recovery procedures or face downtime.

In contrast, while other practices may have merit in specific contexts, they do not encapsulate the breadth of administration and security focus that comes with having an in-cloud Global Administrator account during domain federation processes.