Just a quick post here as I found myself needing to find out what conditional forwarders each domain controller in an Active Directory domain had configured. We have nearly a hundred domain controllers and so going manually one-by-one was simply not an option.

I whipped up this PowerShell script and figured that someone else out there might need something similar. It is parallelized (the number of $instances can be changed to do more/less parallel work) and then just dumps it to a CSV-ish file.

$instances = 10

Get-AdDomainController -Filter * | ForEach-Object -ThrottleLimit $instances -Parallel {
    $dc = $_
    Write-Host $dc.Name
    $zones = Get-DnsServerZone -ComputerName $dc.Name | Where-Object {$_.ZoneType -eq "Forwarder" }
    $string = $dc.Name + ","
     ForEach ($zone in $zones) {
         $string = $string + $zone.ZoneName + ","
     }
    Write-Host $string
    $string | Out-File -FilePath ".\zones.txt" -Append 
}

There’s a lot of room for improvement here obviously, but it should at least get you going.