NetBIOS

Network Basic Input/Output system

NetBIOS is NOT a networking protocol, rather an API.

Originally developed by IBM and later adapted by Microsoft for their NT kernels (Microsoft implemented SMB in Windows NT 3.1), NetBIOS is a naming system for devices in LAN (Kinda like DNS).

It is an API that allows communication of files and printers through the Session Layer (Layer 5) of the OSI Model in a LAN.

In modern networks, NetBIOS normally runs over TCP/IP via the NetBIOS over TCP/IP (NBT) protocol. This results in each computer in the network having both an IP address and a NetBIOS name corresponding to a (possibly different) host name.

NetBIOS is also used for identifying system names in Windows.

NetBIOS over TCP/IP (NBT or NetBT)

NetBIOS over TCP/IP is a protocol based on the NetBIOS API. The RFC 1001 deals with the NBT protocol.

NetBIOS is not routable and hence scalable on it's own. But it can become so by relying on underlying TCP/IP stack for that. Hence NetBIOS over TCP/IP is used.

NetBT can use both NTLM and Kerberos for Authentication.