Script to test-connection and check if computer object exists in AD

Hello guys, 

I've list of 3600 machines and i've to test connectivity and existence in AD as i'm a beginner in PS , I'd like to request some help.

I have already script to ping machines which are included in .txt file :

$currentDirectory = [System.IO.Path]::GetDirectoryName($myInvocation.MyCommand.Definition)
$inputFile = "$currentDirectory\Computers.txt"
$OutputFile = "$currentDirectory\Report.csv"
$servers = Get-Content $inputFile
$collection = $()
foreach ($server in $servers)
{
    $status = @{ "ServerName" = $server; "TimeStamp" = (Get-Date -f s) }
    if (Test-Connection $server -Count 1 -ea 0 -Quiet)
    { 
        $status["Results"] = "Up"
    } 
    else 
    { 
        $status["Results"] = "Down" 
    }
    New-Object -TypeName PSObject -Property $status -OutVariable serverStatus
    $collection += $serverStatus
}
$collection | export-csv $OutputFile -NoTypeInformation 

And  it returns following output : 

I'd like to have there also info if machine exists in AD and receive output like :

Thanks in advance