Im seeing failed login attempts on our One of our domain controller and all them are originating from Azure AD Sync server. It says that user name "O" does not exist.
The failed login event is coming from C:\Program Files\Microsoft Azure AD Sync\Bin\miiserver.exe. For some reason it's using partial username and domain.
Username: O
Event Code: 4625
Subject: User name does not exist
Both domain controller and Azure AD sync server running on Windows 2008 R2. AD Sync client running on 1.2.69
Thank you,
Gopi