The NetBIOS Name Server (NBNS) protocol does not perform authentication, which allows remote attackers to cause a denial of service by sending a spoofed Name Conflict or Name Release datagram, aka the "NetBIOS Name Server Protocol Spoofing" vulnerability.
https://exchange.xforce.ibmcloud.com/vulnerabilities/5035
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2000/ms00-047