The Maximum Log File Size machine setting should be configured correctly. Specifies the maximum size in bytes of the log file netlogon.log in the directory %windir%\debug when logging is enabled. By default, the maximum size of the log file is 20MB. If this policy is enabled, the maximum size of the log file is set to the specified size. Once this size is reached the log file is saved to netlogon.bak and netlogon.log is truncated. A reasonable value based on available storage should be specified. If this policy is disabled or not configured, the default behavior occurs as indicated above. Fix: (1) GPO: Computer Configuration\Administrative Templates\System\Net Logon\Maximum Log File Size (2) KEY: HKLM\Software\Policies\Microsoft\Netlogon\Parameters\MaximumLogFileSize