Thanks Jeepeepee for the link. I re-post the link in here: Service overview and network port requirements for the Windows Server systemhttp://support.microsoft.com/?kbid=832017 I think it’s very useful when doing diagnostic.
**This article (Q289241) is no longer available via Microsoft Tech Net. SUMMARY This article describes the most common ports, protocols, and services that are opened on a Windows 2000-based server that is running Active Directory. The purpose of this article is to list the different services and their respective ports, not to explain how to configure the ports for either a firewall or a proxy. MORE INFORMATION 21/TCP (Transmission Control Protocol) — FTP This File Transfer Protocol (FTP) server is part of Internet Information Services (IIS) and is administered from the IIS administration tool. FTP is a common method to … Continue reading A List of the Windows 2000 Domain Controller Default Ports