The following scenario only applies to Microsoft Office 365 customers who have a hybrid deployment of on-premises Exchange Server and Exchange Online.
You try to use the Microsoft Remote Connectivity Analyzer tool to test Autodiscover redirection in an organization. During the test, the Remote Connectivity Analyzer tool tool sends an anonymous HTTP request from the remote server to the URL that's responding with the Autodiscover address for the on-premises hybrid server. If the request succeeds, but anonymous access should not be enabled on this virtual directory, you receive the following error message in the tool:
Anonymous authentication enabled for virtual directory.
This issue occurs because the following applications and services require specific authentication methods:
- Outlook Web App
- Microsoft Exchange ActiveSync
- Outlook Anywhere (formerly known as RPC over HTTP)
- Other Exchange Web Services such as the Availability Service and web-distributed Offline Address Books
If anonymous access is enabled instead of, or in addition to, other required authentication methods, your server is not as secure from a security perspective, and unexpected results can occur.
To resolve this issue, review the following documentation and confirm that the correct authentication methods for each application or service are enabled for the virtual directories on your Exchange server:
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