NBNS serves much the same purpose as DNS does: translate human-readable names to IP addresses e.g. to As NetBIOS can run on top of several different network protocols e.g. IP, IPX, …, other implementations of the NetBIOS services have their own mechanisms for translating NetBIOS names to addresses. NBNS’s services are more limited, in that NetBIOS names exist in a flat name space, rather than DNS’s hierarchical one multiple flat name spaces can exist, by using NetBIOS scopes, but those are rarely used, and NBNS can only supply IPv4 addresses; NBNS doesn’t support IPv6.

via NetBIOS/NBNS – The Wireshark Wiki.