I believe every System Administrator should know about the log files for troubleshooting Windows Server. These logs are great help for troubleshooting lot of Windows related problems from windows update to Group Policies. Windows Generates log for every process that has been done on the server. Listed below are some of the log files you should check in case of failures.
The DcpromoUI.log file contains a detailed progress report of the Active Directory installation and removal processes. Its default location is the % SystemRoot %\Debug folder on Windows 2000–based servers. Logging begins when the Active Directory Installation Wizard is opened and continues until the summary screen appears; regardless of whether it terminated prematurely or completed successfully. If the installation or removal failed, detailed error messages appear in the log immediately after the step that caused the failure. When the installation or removal process is successful, the log provides positive confirmation of that fact.
When joining a computer to a Windows 2000 domain, the Networking Setup (NetSetup) installs all the necessary Microsoft supported networking components. The Netsetup.log file provides information about the attempts to join domains and records any errors that might be preventing the join from being successful. Also, to install networking components not directly supported by Microsoft, the NetSetup tool provides a way to connect into the setup process for third-party components.
The output of this log file can be helpful in troubleshooting problems with user profiles and Group Policy processing. The log file resides in the % SystemRoot %\Debug folder.
The Net Logon service responds to network logon requests. The Net Logon service dynamically creates records in the DNS database that are used to locate a server.
The File Replication service (FRS) text-based log file is the Ntfrsapi.log file. It resides in the % SystemRoot %\Debug folder. It tracks replication problems and contains events that take place during the installation or removal of Active Directory, for example, creating the NTFRS registry keys
Thanks to Syed Khairuddin for the original post : http://www.virmansec.com/blogs/skhairuddin/archive/2011/06/29/windows-log-files-for-troubleshooting.aspx