The NetBIOS Name Service (NBNS) provides a means for hostname and address mapping on a NetBIOS-aware network. The NetBIOS over TCP/IP protocols (including NBNS) are described in the Internet Engineering Task Force (IETF) Request for Comments RFC1001 and RFC1002. These protocols do not specify a method for authenticating communications, and as such, machines running NetBIOS services are vulnerable to spoofing attacks. NetBIOS is a set of defined software interfaces for vendor-independent PC networking and is primarily used on Microsoft Windows computers. NetBIOS is enabled by default on Windows95 and Windows98 machines.