The Windows DNS service may not recreate the debug log file after rollover. If you get hit by the issue, make sure to use the C: drive for the debug log path.
The Windows DNS debug log
The Windows DNS debug log contains information on DNS queries and activity that can be important to monitor and analyze to detect malicious traffic. This requires some configuration changes for the DNS service in order to enable debug logging. Here is a short description on how to enable debug logging for the DNS service on windows, this also applies to Windows 2008 and later. It is possible to specify the file and path name of the DNS debug log file as well as the maximum size of the file.