Get-DomainADUser

Function Get-DomainADUser {
    <#
        .DESCRIPTION
        Locate's AD user across multiple domains.

        .PARAMETER UserID
        Specifies the user to find, accepts UPN and SAM.

        .EXAMPLE
        Get-DomainADUser -UserID first.last

        .EXAMPLE
        Get-DomainADUser -UserID first.last@domain.com

        .EXAMPLE
        Get-DomainADUser -UserID S-1-6-21-1234567890-1234567890-123456789-1234

        .NOTES
        Before running this script update the domains and domain names noted by d1,d2,d3, and d4 or d1.domain.com, d2.domain.com, d3.domain.com, or d4.domain.com before running the first time. This requires .
    #>


    Param(
        [Parameter(mandatory=$True)] [string]$UserID
    )
    # IDENTIFY LOCAL SITE 
    import-module activedirectory

    $LocalSite = (Get-ADDomainController -Discover).Site
    $NewTargetGC = Get-ADDomainController -Discover -Service 6 -SiteName $LocalSite
    IF (!$NewTargetGC){ 
        $NewTargetGC = Get-ADDomainController -Discover -Service 6 -NextClosestSite 
    }
    
    # SELECT LOCAL DC
    $NewTargetGCHostName = $NewTargetGC.HostName
    $LocalGC = “$NewTargetGCHostName” + “:3268”

    #Write-Output “Identify User and Computer Objects with configured Service Principal Names `r ”
    #Get-ADUser $UserID -Server “$LocalGC”

    # QUERY Global Catelog
    if($UserID -match "@"){
        $GC_UserData = Get-ADUser -Server $LocalGC -filter { UserPrincipalName -eq $UserID }
    }
    elseif($UserID -match "s-1-"){
        $GC_UserData = Get-ADUser -Server $LocalGC -filter { SID -eq $UserID }
    }
    else{
        $GC_UserData = Get-ADUser -Server $LocalGC -filter { SamAccountName -eq $UserID }
    }

    # Shut function down if user is not found. 
    if (!($GC_UserData)){
            Write-Host "Exiting"
            Write-Host "User Doesn't Exist"
            break
        }

    # IDENTIFY User's Domain
    $DN = $GC_UserData.DistinguishedName
    If ($DN) {
        $DN = $DN.Split(',')
        If ($DN -contains "DC=d2"){
            #Write-Host user is in d2
            $Domain = "d1.domain.com"
        }
        elseIf ($DN -contains "DC=d2"){
            #Write-Host user is in d2
            $Domain = "d2.domain.com"
        }
        elseIf ($DN -contains "DC=d3"){
            #Write-Host user is in d3
            $Domain = "d3.domain.com"
        }
        elseIf ($DN -contains "DC=d4"){
            #Write-Host user is in d4 Domain
            $Domain = "d4.domain.com"
        }
        else {
            Write-Host "user doesn't exist."
        }
    }
    Else {$Domain = "user doesn't exist."}
    
    if($UserID -match "@"){
        $DC_UserData = Get-ADUser -Properties * -Server $Domain -filter { UserPrincipalName -eq $UserID } | select *
    }
    elseif($UserID -match "s-1-"){
        $Domain
        #$DC_UserData = Get-ADUser -Properties * -Server $Domain -filter { SID -eq $UserID } | select *
    }
    else{
        $DC_UserData = Get-ADUser -Properties * -Server $Domain -filter { SamAccountName -eq $UserID } | select *
    }

    $DC_UserData 
}