Active Directory · Risk: High · Documentation Verified
Last verified: 2026-10-26
Microsoft ActiveDirectory reference: Modifies an Active Directory forest. The syntax and selected example below are adapted from the pinned Windows Server 2025 reference. Module availability, target configuration and delegated permissions determine whether it can run in your environment. Documentation and parameter text: Microsoft, CC BY 4.0; formatting adapted by Cmdlet World. No execution testing is claimed.
Use an account with the target resource permissions documented for Set-ADForest. Modifying administrative cmdlets may require elevation or delegated administration. This catalog does not assert that ordinary users can execute the command.
Supported environments
Windows / ActiveDirectory · Windows Server 2025 documentation; feature/module prerequisites apply
Parameters
-AuthType
Specifies the authentication method to use. The acceptable values for this parameter are: - Negotiate or 0 - Basic or 1 The default authentication method is Negotiate. A Secure Sockets Layer (SSL) connection is required for the Basic authentication method.
-Confirm
Prompts you for confirmation before running the cmdlet.
-Credential
Specifies the user account credentials to use to perform this task. The default credentials are the credentials of the currently logged on user unless the cmdlet is run from an Active Directory module for Windows PowerShell provider drive. If the cmdlet is run from such a provider drive, the account associated with the drive is the default. To specify this parameter, you can type a user name such as User1 or Domain01\User01, or you can specify a PSCredential object. If you specify a user name for this parameter, the cmdlet prompts for a password. You can also create a PSCredential object by using a script or by using the Get-Credential cmdlet. You can then set the *Credential* parameter to the PSCredential object. If the acting credentials do not have directory-level permission to perform the task, Active Directory module for Windows PowerShell returns a terminating error.
-Identity (required)
Specifies an Active Directory forest object by providing one of the following attribute values. The identifier in parentheses is the Lightweight Directory Access Protocol (LDAP) display name for the attribute. The acceptable values for this parameter are: - A fully qualified domain name - A GUID (objectGUID) - A DNS host name - A NetBIOS name The cmdlet searches the default naming context or partition to find the object. If two or more objects are found, the cmdlet returns a non-terminating error. This parameter can also get this object through the pipeline or you can set this parameter to a forest object instance.
-PassThru
Returns an object representing the item with which you are working. By default, this cmdlet does not generate any output.
-SPNSuffixes
Modifies the list of service principal name (SPN) suffixes of the forest. This parameter sets the multi-valued msDS-SPNSuffixes property of the cross-reference container. This parameter uses the following syntax to add remove, replace, or clear SPN suffix values. To add values: -SPNSuffixes @{Add=value1,value2,...} To remove values: -SPNSuffixes @{Remove=value3,value4,...} To replace values: -SPNSuffixes @{Replace=value1,value2,...} To clear all values: -SPNSuffixes $Null You can specify more than one change by using a list separated by semicolons. For example, use the following syntax to add and remove SPN suffix values: @{Add=value1,value2,...};@{Remove=value3,value4,...} The operators are applied in the following sequence: - Remove - Add - Replace
-Server
Specifies the Active Directory Domain Services (AD DS) instance to connect to, by providing one of the following values for a corresponding domain name or directory server. The service may be any of the following: Active Directory Lightweight Directory Services (AD LDS), AD DS, or Active Directory snapshot instance. Specify the AD DS instance in one of the following ways: Domain name values: - Fully qualified domain name - NetBIOS name Directory server values: - Fully qualified directory server name - NetBIOS name - Fully qualified directory server name and port The default value for this parameter is determined by one of the following methods in the order that they are listed: - By using the *Server* value from objects passed through the pipeline - By using the server information associated with the AD DS Windows PowerShell provider drive, when the cmdlet runs in that drive - By using the domain of the computer running Windows PowerShell
-UPNSuffixes
Modifies the list of user principal name (UPN) suffixes of the forest. This parameter sets the multi-valued msDS-UPNSuffixes property of the cross-reference container. This parameter uses the following syntax to add remove, replace, or clear UPN suffix values. To add values: -UPNSuffixes @{Add=value1,value2,...} To remove values: -UPNSuffixes @{Remove=value3,value4,...} To replace values: -UPNSuffixes @{Replace=value1,value2,...} To clear all values: -UPNSuffixes $Null You can specify more than one change by using a list separated by semicolons. For example, use the following syntax to add and remove UPN suffix values: @{Add=value1,value2,...};@{Remove=value3,value4,...} The operators are applied in the following sequence: - Remove - Add - Replace
-WhatIf
Shows what would happen if the cmdlet runs. The cmdlet is not run.
Prerequisites
Windows with the ActiveDirectory module and the Windows feature or management tools that provide it. Confirm target connectivity and version compatibility using the linked Microsoft reference.
Security considerations
This cmdlet changes system state. Review every target and parameter in the official reference, test outside production, and prepare an appropriate backup or rollback. Do not execute the example automatically.
This command sets the UPNSuffixes property for the fabrikam.com forest. Source: Microsoft, CC BY 4.0; transcript prompt/output removed. This example was not executed.