MSS: (NoNameReleaseOnDemand) Allow the computer to ignore NetBIOS name release requests except from WINS servers
This value controls whether NetBIOS over TCP/IP (NetBT) responds to requests to release a registered NetBIOS name.
since 0.9.8.11
Purpose
Show registry keys (1)
HKLM\SYSTEM\CurrentControlSet\Services\Netbt\Parameters\NoNameReleaseOnDemand
This value controls whether NetBIOS over TCP/IP (NetBT) responds to requests to release a registered NetBIOS name. With REG_DWORD data set to 1, the computer retains its name when it receives such a request.
The setting applies only to NetBIOS name release requests. It does not control the separate handling of NetBIOS name conflict datagrams.
Notes
Security
The NetBIOS Name Service protocol does not reliably authenticate its management messages. An attacker on a reachable network can therefore spoof a name release request that would otherwise cause a computer to relinquish its NetBIOS name and stop answering service requests addressed to that name. Setting the value to 1 mitigates this denial-of-service technique.
The setting does not determine whether an individual request is genuinely spoofed. Instead, it changes how name release requests are handled in general. It does not protect against other attacks on NetBIOS or name resolution.
Possible side effects
A legitimate name release request might also have no effect. Genuine duplicate NetBIOS names can consequently persist, and name conflicts might not be resolved automatically. Microsoft specifically describes a conflict detected by a WINS server during replication as a possible case. Depending on the names involved, this can disrupt access to network services or important domain functionality.
Notes
Microsoft’s current baseline title describes an exception for requests from WINS servers. An older Microsoft security bulletin instead describes the value as rejecting all name release datagrams and explicitly gives an unresolved conflict reported by a WINS server as a possible consequence. Microsoft documentation is therefore not consistent about the WINS exception, and that exception should not be assumed to apply identically across Windows versions.
The value is relevant only where NetBIOS over TCP/IP is in use. Microsoft documented the functionality for Windows 2000, and the setting is also present in the Windows Server 2025 security baseline.
Microsoft documentation
Microsoft Learn: Windows security baseline for Windows Server 2025
Microsoft Learn: Microsoft Security Bulletin MS00-047