Public/Get-DirectoryServicesDomainController.ps1

function Get-DirectoryServicesDomainController {
    [CmdletBinding()]
    Param(
        [Parameter(
            Mandatory = $false,
            Position = 0
        )]
            [String]$Domain = (Get-CimInstance Win32_ComputerSystem | select -ExpandProperty Domain)
    )
    # Get a list of domain controllers
    (Get-DirectoryServicesDomain -Domain $Domain).DomainControllers
}