Require strict KDC validation: registry value KdcValidationComputerHKLM\Software\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters

Policy ID: ValidateKDC
Scope: Computer Configuration
Supported on: At least Windows Vista
Source: Administrative Templates (.admx) for Windows 11 2026 Update (26H2) (version 1.0)
Category: System › Kerberos

Registry

KdcValidation

REG_DWORDComputer

HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters Current key

Enabled value: 2
Disabled value: 0

Apply with .reg · CMD · PowerShell

.reg

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters]

; Options (use only one)
; Enabled
"KdcValidation"=dword:00000002
; Disabled
"KdcValidation"=dword:00000000

CMD

:: Options (use only one)

:: Enabled
reg add "HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters" /v "KdcValidation" /t REG_DWORD /d 2 /f
:: Disabled
reg add "HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters" /v "KdcValidation" /t REG_DWORD /d 0 /f

PowerShell

# Common: create the key
New-Item -Path 'HKLM:\Software\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters' -Force | Out-Null

# Options (use only one)
# Enabled
New-ItemProperty -Path 'HKLM:\Software\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters' -Name 'KdcValidation' -PropertyType DWord -Value 2 -Force | Out-Null
# Disabled
New-ItemProperty -Path 'HKLM:\Software\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters' -Name 'KdcValidation' -PropertyType DWord -Value 0 -Force | Out-Null