[CmdletBinding()]
param()
# Copyright (C) 2014, Svendsen Tech. All rights reserved.
# Joakim Borger Svendsen
# 2014-08-15
# edited: 2014-11-08

$DnsServer = 'your.dns.server'

# This uses DnsShell to get the zones, but you can edit this to read
# zones from a file, or whatever, to avoid DnsShell.
# It uses dnscmd.exe below and parses its output, and then uses the
# (apparently obsolete) [Net.Dns] class' GetHostByAddress() method
# to look up the IP (there is no way to specify the DNS server here,
# as far as I can tell).
####
#### Zones must be in the form 58.10.in-addr.arpa (for 10.58.0.0/16).
####

Import-Module .\DnsShell # this has to exist ( http://dnsshell.codeplex.com/ )
$Zones = Get-DnsZone -Server $DnsServer
$ReverseZones = $Zones | Where { $_.ZoneName -like '*.arpa' } | Select -ExpandProperty ZoneName # @('58.10.in-addr.arpa') # = 

foreach ($z in $ReverseZones) {
    Write-Host -Fore Green "Processing zone: $z" -NoNewline
    $Records = dnscmd.exe $DnsServer /ZonePrint $z # Get all records and parse them looking for duplicates below.
    #Write-Host -Fore Yellow " -- Num lines:" $Records.Count
    $Records | ForEach-Object -Begin { $IpHash = @{}; $Ctr = 0 } `
        -Process {
            if ($_ -match '^([\d.]+)\s+.*PTR\s+(\S+)\.$') {
                $IpEndReversed = $matches[1]
                #Write-Verbose $IpEndReversed
                $Ctr++
                Start-Sleep -Milliseconds 25
                $TempArray = $z -replace '\.in-addr\.arpa$' -split '\.'
                $IpStart = ($TempArray[-1..-($TempArray.Count)]) -join '.'
                $TempArray = $IpEndReversed -split '\.'
                $IpEnd = ($TempArray[-1..-($TempArray.Count)]) -join '.'
                #Write-Verbose $IpEnd
                $Ip = "$IpStart.$IpEnd"
                
                #Write-Verbose "Looking up $Ip..."
                $ErrorActionPreference = 'Stop'
                try {
                    $Dns = [Net.Dns]::GetHostByAddress($Ip)
                    # This means we found a duplicate. Send an object down the pipeline.
                    if ($Dns.Aliases -match '\S') {
                        New-Object psobject -Property @{
                            IP = $Ip
                            HostName = $Dns.HostName -join ', '
                            Aliases = $Dns.Aliases -join ', '
                            Error = $null
                        }
                    }
                }
                catch {
                    New-Object psobject -Property @{
                        IP = $Ip
                        HostName = $null
                        Aliases = $null
                        Error = $_
                    }
                }
                $ErrorActionPreference = 'Continue'
            }
        }
    Write-Host -Fore Yellow " -- Num records:" $Ctr
    #Write-Verbose "Processed $Ctr PTR records for $z"
    #Start-Sleep -Seconds 3
}