NetBIOS

NetBIOS is an application programming interface (API ) that allows older windows computers to communicate with each other. It does not need to be configured in order to provide name resolution.
Windows 2003 server uses NetBIOS as a backup to DNS and to implement features such as browsing the network neighbourhood or My Network places.
NetBIOS is required for the following Networks:
1) Windows 2003 server networks support NetBIOS over TCP/IP ( Net BT) to provide backward compatability with previous versions of windows and for compatability with NetBIOS application.
2) Microsoft windows NT domains use NetBIOS names and NetBIOS protocol.
3) Necessary for network clients using applications that require NetBIOS name resolution.
As an example is the computer browser service which allows network browsing through windows network icon in windows explorer.
4) Required in networks for which DNS has not yet fully configured . An example is a computer workgroup in which no DNS server has been installed . NetBIOS broadcasts are required to resolve computer names.