Public/Get-ADSIDomainRoot.ps1

function Get-ADSIDomainRoot
{
<#
    .SYNOPSIS
        Function to retrieve the Domain Root in the Forest
     
    .DESCRIPTION
        Function to retrieve the Domain Root in the Forest
     
    .PARAMETER Credential
        Specifies the alternative credential to use. Default is the current one.
     
    .PARAMETER ForestName
        Specifies the alternative forest name to query. Default is the current one.
     
    .NOTES
        Francois-Xavier Cat
        lazywinadmin.com
        @lazywinadm
        github.com/lazywinadmin
#>

    
    [CmdletBinding()]
    [OutputType([System.DirectoryServices.ActiveDirectory.Domain])]
    param
    (
        [System.Management.Automation.Credential()]
        [Alias('RunAs')]
        $Credential = [System.Management.Automation.PSCredential]::Empty,
        
        $ForestName = [System.DirectoryServices.ActiveDirectory.Forest]::Getcurrentforest()
    )
    
    (Get-ADSIForest @PSBoundParameters).RootDomain
}