Microsoft Knowledge Base Article 236033 contains the following summary:
You can enable a Windows 2000 Remote Install Server (RIS)
to run in Debug mode for troubleshooting purposes. This can be useful when you
are trying to troubleshoot client/server issues (such as pre-staged systems not
connecting to the RIS server, or clients not receiving information sent to or
from the RIS server).
There are two debugging modes that you can enable. The first is Normal Debug mode, which logs output to a file. The other is Full Debug mode, which displays output via NTSD or Kernel Debugger. Both of these options require manual editing of the registry.