Do not use NetBIOS-based discovery for domain controller location when DNS-based discovery fails
Verified with Windows 11 25H2 — updated on July 30, 2026
Supported on: At least Windows Server 2012, Windows 8 or Windows RT
Path in the GPO console
Computer Configuration\Administrative Templates\System\Net Logon\DC Locator DNS Records Description
This policy setting allows you to control the domain controller (DC) location algorithm. By default, the DC location algorithm prefers DNS-based discovery if the DNS domain name is known. If DNS-based discovery fails and the NetBIOS domain name is known, the algorithm then uses NetBIOS-based discovery as a fallback mechanism. NetBIOS-based discovery uses a WINS server and mailslot messages but does not use site information. Hence it does not ensure that clients will discover the closest DC. It also allows a hub-site client to discover a branch-site DC even if the branch-site DC only registers site-specific DNS records (as recommended). For these reasons, NetBIOS-based discovery is not recommended. Note that this policy setting does not affect NetBIOS-based discovery for DC location if only the NetBIOS domain name is known. If you enable or do not configure this policy setting, the DC location algorithm does not use NetBIOS-based discovery as a fallback mechanism when DNS-based discovery fails. This is the default behavior. If you disable this policy setting, the DC location algorithm can use NetBIOS-based discovery as a fallback mechanism when DNS based discovery fails. This setting has no effect unless the BlockNetbiosDiscovery setting is disabled. NetBIOS-based discovery is considered unsecure, has many limitations, and will be deprecated in a future release. For these reasons, NetBIOS-based discovery is not recommended. See https://aka.ms/dclocatornetbiosdeprecation for more information.
Registry
Software\Policies\Microsoft\Netlogon\Parameters Value name: AvoidFallbackNetbiosDiscovery
Enabled: AvoidFallbackNetbiosDiscovery = 1
Disabled: AvoidFallbackNetbiosDiscovery = 0
MDM / Intune (CSP)
./Device/Vendor/MSFT/Policy/Config/ADMX_Netlogon/Netlogon_AvoidFallbackNetbiosDiscovery Microsoft Learn documentation Mapping data: Microsoft Learn (CC BY 4.0)
Export Builder
BETAConfigure the state, scope and options, then generate .reg, PowerShell, Intune and SCCM outputs — or add the setting to a multi-setting collection.
These exports write the registry — this is not a managed GPO. ⓘ
.reg file
Windows Registry Editor Version 5.00
; Exported from gporais.com
; Policy: Do not use NetBIOS-based discovery for domain controller location when DNS-based discovery fails
; State: Enabled
; Supported on: At least Windows Server 2012, Windows 8 or Windows RT
[HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Netlogon\Parameters]
"AvoidFallbackNetbiosDiscovery"=dword:00000001More formats (PowerShell, Intune, SCCM)
PowerShell
# Exported from gporais.com
# Policy: Do not use NetBIOS-based discovery for domain controller location when DNS-based discovery fails
# State: Enabled
# Supported on: At least Windows Server 2012, Windows 8 or Windows RT
$path = 'HKLM:\Software\Policies\Microsoft\Netlogon\Parameters'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'AvoidFallbackNetbiosDiscovery' -Value 1 -Type DWordIntune XML
OMA-URI: ./Device/Vendor/MSFT/Policy/Config/ADMX_Netlogon/Netlogon_AvoidFallbackNetbiosDiscovery
Data type: String
Value:
<enabled/>Intune Remediation
# === Detection script ===
# Exported from gporais.com
# Policy: Do not use NetBIOS-based discovery for domain controller location when DNS-based discovery fails
# State: Enabled
# Supported on: At least Windows Server 2012, Windows 8 or Windows RT
function Test-RegistryValue {
param(
[Parameter(Mandatory = $true)][string]$Path,
[Parameter(Mandatory = $true)][string]$Name,
[object]$Expected,
[ValidateSet('String', 'DWord', 'MultiString')][string]$Kind = 'String',
[switch]$Absent
)
try {
$item = Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction Stop
} catch {
return $Absent.IsPresent
}
if ($Absent.IsPresent) { return $false }
$actual = $item.$Name
if ($Kind -eq 'DWord') { return ([int64]$actual) -eq ([int64]$Expected) }
if ($Kind -eq 'MultiString') {
$actualValues = @($actual)
$expectedValues = @($Expected)
if ($actualValues.Count -ne $expectedValues.Count) { return $false }
for ($i = 0; $i -lt $expectedValues.Count; $i++) {
if ([string]$actualValues[$i] -ne [string]$expectedValues[$i]) { return $false }
}
return $true
}
return [string]$actual -eq [string]$Expected
}
$checks = @(
(Test-RegistryValue -Path 'HKLM:\Software\Policies\Microsoft\Netlogon\Parameters' -Name 'AvoidFallbackNetbiosDiscovery' -Expected 1 -Kind DWord)
)
if ($checks -notcontains $false) {
Write-Output 'Compliant'
exit 0
}
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Do not use NetBIOS-based discovery for domain controller location when DNS-based discovery fails
# State: Enabled
# Supported on: At least Windows Server 2012, Windows 8 or Windows RT
$path = 'HKLM:\Software\Policies\Microsoft\Netlogon\Parameters'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'AvoidFallbackNetbiosDiscovery' -Value 1 -Type DWordSCCM scripts
# Exported from gporais.com
# Policy: Do not use NetBIOS-based discovery for domain controller location when DNS-based discovery fails
# State: Enabled
# Supported on: At least Windows Server 2012, Windows 8 or Windows RT
# SCCM Configuration Item guidance:
# Create a Configuration Item of type "Setting: Script".
# Discovery script: use the Detection script below.
# Remediation script: use the Remediation script below.
# Compliance rule: the Discovery script output equals 'Compliant'.
# === Detection script ===
# Exported from gporais.com
# Policy: Do not use NetBIOS-based discovery for domain controller location when DNS-based discovery fails
# State: Enabled
# Supported on: At least Windows Server 2012, Windows 8 or Windows RT
function Test-RegistryValue {
param(
[Parameter(Mandatory = $true)][string]$Path,
[Parameter(Mandatory = $true)][string]$Name,
[object]$Expected,
[ValidateSet('String', 'DWord', 'MultiString')][string]$Kind = 'String',
[switch]$Absent
)
try {
$item = Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction Stop
} catch {
return $Absent.IsPresent
}
if ($Absent.IsPresent) { return $false }
$actual = $item.$Name
if ($Kind -eq 'DWord') { return ([int64]$actual) -eq ([int64]$Expected) }
if ($Kind -eq 'MultiString') {
$actualValues = @($actual)
$expectedValues = @($Expected)
if ($actualValues.Count -ne $expectedValues.Count) { return $false }
for ($i = 0; $i -lt $expectedValues.Count; $i++) {
if ([string]$actualValues[$i] -ne [string]$expectedValues[$i]) { return $false }
}
return $true
}
return [string]$actual -eq [string]$Expected
}
$checks = @(
(Test-RegistryValue -Path 'HKLM:\Software\Policies\Microsoft\Netlogon\Parameters' -Name 'AvoidFallbackNetbiosDiscovery' -Expected 1 -Kind DWord)
)
if ($checks -notcontains $false) {
Write-Output 'Compliant'
exit 0
}
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Do not use NetBIOS-based discovery for domain controller location when DNS-based discovery fails
# State: Enabled
# Supported on: At least Windows Server 2012, Windows 8 or Windows RT
$path = 'HKLM:\Software\Policies\Microsoft\Netlogon\Parameters'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'AvoidFallbackNetbiosDiscovery' -Value 1 -Type DWordBuilding a multi-setting collection? Add this setting and generate combined .reg / PowerShell / GPO scripts.