Finding Duplicate IP Addresses and Duplicate Names in a DNS Zone

##
## build-dns-objects.ps1
##

##
## Michael B. Smith
## michael (at) TheEssentialExchange.com
## April, 2012
##

##
## Primary functionality:
##
## Based on either an input file or the output of a default command:
##
## 	dnscmd ( $env:LogonServer ).SubString( 2 ) /enumrecords $env:UserDnsDomain "@"
##
## Create an array containing all of the DNS objects describing the input.
##
## ----
##
## Secondary functionality:
##
## Find all the duplicate IP addresses and the duplicate names 
## contained within either the file or the command output.
##
## By specifying the -skipRoot option, all records for the root of
## the domain are ignored.
##

##
## General record format returned by DNScmd.exe:
##
##	name
##	[aging:xxxxxxxx] 
##	TTL
##	resource-record-type
##	value
##	[optional additional values]
##
## Fields may be separated by one-or-more spaces or one-or-more tabs
## [aging:xxxxxxxx] fields are optional
##

Param(
	[string]$filename,
	[switch]$skipRoot
)

function new-dns-object
{
	return ( "" | Select Name, Aging, TTL, RRtype, Value )
}

function tmpFileName
{
	[string] $strFile = ( Join-Path $Env:Temp ( Get-Random ) ) + ".txt"

	if( ( Test-Path -Path $strFile -PathType Leaf ) )
	{
		rm $strNetworkFile -EA 0
		if( $? )
		{
		##	write-output "...file was deleted"
		}
		else
		{
		##	write-output "...couldn't delete file, error: $($error[0].ToString())"
		}
	}

	return $strFile
}

if( $filename -and ( $filename.Length -gt 0 ) )
{
	$tmp = $filename
}
else
{
	$tmp = tmpFileName
	dnscmd ( $env:LogonServer ).SubString( 2 ) /enumrecords $env:UserDnsDomain "@" >$tmp
}

$objects = @()
$records = gc $tmp

$script:zone = ''

## Primary functionality:

foreach( $record in $records )
{
	## write-output "Processing: $record"

	if( !$record )
	{
		continue
	}
	if( $record -eq "Returned records:" )
	{
		continue
	}
	if( $record -eq "Command completed successfully." )
	{
		continue
	}

	$firstChar = $record.SubString( 0, 1 )
	$record = $record.Trim()

	if( $record.Length -eq 0 )
	{
		continue
	}

	$object = new-dns-object

	$index = 0

	$record = $record.Replace( "`t", " " )

	$array = $record.Split( ' ' )
	if( ( $firstchar -eq " " ) -or ( $firstchar -eq "`t" ) )
	{
		$object.Name = $script:Zone
	}
	else
	{
		$object.Name = $array[ 0 ]
		$script:Zone = $array[ 0 ]
		$index++
	}

	if( ( $array[ $index ].Length –ge 3 ) –and ( $array[ $index ].SubString( 0, 3 ) –eq “[Ag” ) )  ## [Aging:3604987]
	{
		$object.Aging = $array[ $index ]
		$index++
	}

	$object.TTL    = $array[ $index ]
	$object.RRType = $array[ $index + 1 ]
	$object.Value  = $array[ $index + 2 ]

	$objects += $object
}

## Secondary functionality:

## There are more efficient ways to do this, but this is easy.

## search for duplicate names

$hash = @{}
foreach( $o in $objects )
{
	if( $o.RRtype -eq "A" )
	{
		$name = $o.Name
		if( $skipRoot -and ( $name -eq "@" ) )
		{
			continue
		}
		if( $hash.$name )
		{
			"Duplicate name: $name, IP: $($o.Value), original IP: $($hash.$name)"
		}
		else
		{
			$hash.$name = $o.Value
		}
	}
}
$hash = $null

## search for duplicate IP addresses

$hash = @{}
foreach( $o in $objects )
{
	if( $o.RRtype -eq "A" )
	{
		if( $skipRoot -and ( $o.Name -eq "@" ) )
		{
			continue
		}

		$ip = $o.Value
		if( $hash.$ip )
		{
			"Duplicate IP: $ip, name: $($o.Name), original name: $($hash.$ip)"
		}
		else
		{
			$hash.$ip = $o.Name
		}
	}
}
$hash = $null

" "
"Done"