I know that this is a bit of an old question, but I would like to expand on the answer given, to aid anyone else who had a similar query.
The following allows you to define a specific Domain Controller, which the entire of a script would be able to use... Why might you want to do this when the -server parameter is available to Get-ADUser, New-ADUser, Set-ADObject, etc?
Well I put together a script that creates an AD user, sets multiple properties and creates an exchange mailbox - However, one set of properties revolves around the RDS properties on a 2008 R2 user account, which cannot be set from within New-ADUser. I had to create a function that calls ADSI and uses psbase.invokeSet to update the settings. There is no parameter setting for -server that I'm aware of.
This in itself wouldn't be a big deal, but the script also creates an Exchange mailbox for the user. As my Exchange server is in different AD Site from my workstation, the user account gets created on my local DC, but the mailbox isn't set, because the DC in the same site as the Exchange server hasn't yet received a replicated copy of the new user account.
The solution I found is as follows and is courtesy of http://www.joseph-streeter.com/?p=799
Having loaded import-module activedirectory, you'll have access to AD options in the New-PSDrive commandlet which among everything else allows you to define a new Active Directory Provider to work with.
New-PSDrive -Name <<NameofYourChoice>> -PSProvider ActiveDirectory -Server <<DC Server>> -Root "//RootDSE/" -Scope Global
Once created, you can then change the working Provider with the following command.
CD <<NameofYourChoice>>:
To view the existing list of Providers, type Get-PSDrive. AD is the default Active Directory Provider created when using the ActiveDirectory commandlet. You should also see your newly created Provider.
So for instance if my remote DC is called RemoteDC I would run:
New-PSDrive -Name RemoteAD -PSProvider ActiveDirectory -Server RemoteDC -Root "//RootDSE/" -Scope Global
to create a new Provider called RemoteAD. If I then run:
CD RemoteAD:
All further active directory related commands in the script or the active shell will work with the new Provider RemoteAD. If I would need to change back to my original Provider, I'd simply type
CD AD:
Hope someone finds this useful...