Duplicates in the results of my scan...not sure why?

Question

Hello,
I'm using the following bit of code to scan all computers in a file to look for the IP Address, Subnet Mask, DNS Servers, MAC Address and Gateway.
It's working, but I'm seeing in my results sometimes multiple lines of exactly the same information for some of the computers I'm scanning?  I'm asking this community if they can think of why this would occur?
Thank you.
Here is my code:
$dataColl = @()#Makes an array, or a collection to hold all the object of the same fields.
$outputresults = "C:\Apps\Powershell_Scripts\Diskspace\subnetscan.csv"
#process {
foreach ($Computer in (get-content C:\Apps\Powershell_Scripts\Diskspace\servers.txt))
if(Test-Connection -ComputerName $Computer -Count 1 -ea 0) {
$Networks = Get-WmiObject Win32_NetworkAdapterConfiguration -ComputerName $Computer | ? {$_.IPEnabled}
foreach ($Network in $Networks) {
$IPAddress = $Network.IpAddress[0]
$SubnetMask = $Network.IPSubnet[0]
$DefaultGateway = $Network.DefaultIPGateway
$DNSServers = $Network.DNSServerSearchOrder
$IsDHCPEnabled = $false
If($network.DHCPEnabled) {
$IsDHCPEnabled = $true
$MACAddress = $Network.MACAddress
$OutputObj = New-Object -Type PSObject
$OutputObj | Add-Member -MemberType NoteProperty -Name ComputerName -Value $Computer.ToUpper()
$OutputObj | Add-Member -MemberType NoteProperty -Name IPAddress -Value ($IPAddress -join ",")
#$OutputObj | Add-Member -MemberType NoteProperty -Name IPAddress -Value $IPAddress
$OutputObj | Add-Member -MemberType NoteProperty -Name SubnetMask -Value $SubnetMask
#$OutputObj | Add-Member -MemberType NoteProperty -Name Gateway -Value $DefaultGateway
$OutputObj | Add-Member -MemberType NoteProperty -Name Gateway -Value ($DefaultGateway -join “,”)
#$OutputObj | Add-Member -MemberType NoteProperty -Name IsDHCPEnabled -Value $IsDHCPEnabled
$OutputObj | Add-Member -MemberType NoteProperty -Name DNSServers -Value ($DNSServers -join ",")
$OutputObj | Add-Member -MemberType NoteProperty -Name MACAddress -Value $MACAddress
$dataColl += $OutputObj
$dataColl | Export-Csv -noTypeInformation -path $outputresults

Answer 1

Are you running PowerShell 2.0, by chance?  Your code looks like it should work fine on PowerShell 3.0 or later, but there's one little "gotcha" with foreach loops in PowerShell 2.0:
$collection = $null
foreach ($item in $collection)
Write-Host "Loop Body Executed"
In PowerShell 2.0, the loop body will execute once, which people tend not to expect.  This was treated as a bug, and in PowerShell 3.0, if the collection is null, the loop doesn't do anything.  Even with that bug taken into account, I'm not sure
how you're getting duplicate results, but you can try adding a check to make sure $Networks is not null before you enumerate over it, just to see if it helps:
$outputresults = "C:\Apps\Powershell_Scripts\Diskspace\subnetscan.csv"
get-content C:\Apps\Powershell_Scripts\Diskspace\serverstst.txt |
ForEach-Object {
$computer = $_
if (Test-Connection -ComputerName $Computer -Count 1 -ea 0) {
$Networks = Get-WmiObject Win32_NetworkAdapterConfiguration -ComputerName $Computer | ? {$_.IPEnabled}
if ($Networks)
foreach ($Network in $Networks) {
$IPAddress = $Network.IpAddress[0]
$SubnetMask = $Network.IPSubnet[0]
$DefaultGateway = $Network.DefaultIPGateway
$DNSServers = $Network.DNSServerSearchOrder
$IsDHCPEnabled = $false
If ($network.DHCPEnabled) {
$IsDHCPEnabled = $true
$MACAddress = $Network.MACAddress
$OutputObj = New-Object -Type PSObject
$OutputObj | Add-Member -MemberType NoteProperty -Name ComputerName -Value $Computer.ToUpper()
$OutputObj | Add-Member -MemberType NoteProperty -Name IPAddress -Value ($IPAddress -join ",")
#$OutputObj | Add-Member -MemberType NoteProperty -Name IPAddress -Value $IPAddress
$OutputObj | Add-Member -MemberType NoteProperty -Name SubnetMask -Value $SubnetMask
#$OutputObj | Add-Member -MemberType NoteProperty -Name Gateway -Value $DefaultGateway
$OutputObj | Add-Member -MemberType NoteProperty -Name Gateway -Value ($DefaultGateway -join “,”)
#$OutputObj | Add-Member -MemberType NoteProperty -Name IsDHCPEnabled -Value $IsDHCPEnabled
$OutputObj | Add-Member -MemberType NoteProperty -Name DNSServers -Value ($DNSServers -join ",")
$OutputObj | Add-Member -MemberType NoteProperty -Name MACAddress -Value $MACAddress
$OutputObj
} |
Export-Csv -noTypeInformation -path $outputresults