List all Zones on all DNS Servers

cls
Remove-Variable -Name * -Force -ErrorAction SilentlyContinue
$Date = Get-Date
$Filename = "C:\" + "DNSZones" + "_" + $Date.Day + "-" + $Date.Month + "-" + $Date.Year + ".txt"
$computer = 'DNSServer1','DNSServer2','DNSServer3'
foreach ($comp in $computer)
{
$zones = Get-WmiObject -Class MicrosoftDNS_Zone -ComputerName $comp -Namespace root\microsoftDNS
foreach ($zone in $zones)
{
if ($zone.ZoneType -eq '2'-or $zone.ZoneType -eq '1')
{
$tab = '     '
$output = $comp + $tab + $zone.Name
$output | out-file $Filename -Append
}
}
}