Working with arrays in Powershell

Question

Hello everyone,
It has been an hour since I started to work on a new script in Active Directory. It is desired to query user LastLogin among all domain controllers in a domain. In a nutshell it will be used for:
 Query LastLogin of ALL user accounts from ALL domain controllers and compare them to determine the best result.
I know it might takes quite long time for this query to process but since I am not a third-party person, so far I have written this script block:
$DC = Get-ADGroupMember "domain controllers"
$Allusers = get-aduser -Filter * -searchbase "ou=AllUsers,dc=Contoso,dc=Net" -Properties Samaccountname
$i = 0
$j = 0
#Main Part Of The Script#
foreach ($User in $AllUsers)
$LastLogin = $null
$UserArray[$i] = $User.Samaccountname
foreach ($DC in $AllDC)
$UN = Get-ADUser $User -Properties lastlogin -Server $DC
if ([DateTime]::FromFileTime($UN.LastLogin) -ge $LastLogin)
$LastLogin = $UN.LastLogin
$LoginArray[$j] = $LastLogin
$i += 1
$j += 1
Well the questions are:
Is it Optimized?
Since I used two different arrays for this purpose, please kindly suggest me ideas on how to output this two arrays next to each other? ( I am not so professional in Powershell and Arrays especially) :)
Regards.
Mahdi Tehrani Loves Powershell
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Answer 1

Thank you jrv. I highly admire you and David skills in scripting and helping me out. All of the solutions provided works well for me but it seems it does not check the value in first DC. Check below example:
User A
DC 1 = 2/2/2014
DC 2 = 6/3/2013
DC 3 = Null
Result = 6/3/2013
It is really strange. I do not really understand why it should happen. I traced the code manually and IMO it must return 2/2/2014 as the result.
Mahdi Tehrani Loves Powershell
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Yes.  Both code examples can miss a DC.  Add this to the first line: "-Server $DC[0]"  which will force the first query to use the first DC and not the GC.  This would not happen with DAvids code and I will post an updated and faster
version next.
¯\_(ツ)_/¯
 Thanks again for all the helpful replies. Since they were really helpful I voted them all as helpful posts. I thing I have found why it does not return values on first DC. I did apply some slight changes to track query progress:
$domainControllers = @(Get-ADGroupMember "domain controllers")
Write-host "Running The First Query On " $domainControllers[2].Name
$users=Get-ADUser -Filter * -searchbase "ou=AllUsers,dc=Contoso,dc=Net" -Properties Samaccountname,LastLogon -Server $domainControllers[2].name |
Select-Object -Property 'SamAccountName', 'LastLogon'
Write-host -foreground green "Values on" $domainControllers[2].Name
foreach ($US in $Users)
$US.LastLogon = [DateTime]::FromFileTime($US.lastLogon)
$users
Write-host
Write-host -foreground green "Final Values"
#Main Part Of The Script#
foreach ($user in $users){
foreach ($DC in $domainControllers){
if($UN=Get-ADUser -Identity $user.SamAccountName -Properties lastlogon -Server $DC.Name -ea 0){
if($UN.lastLogon -ne 0){
$lastLogon = [DateTime]::FromFileTime($UN.lastLogon)
if($lastLogon -gt $user.LastLogon){
$user.LastLogon=$lastLogon
$users
Using this code I found out that the LastLogon's in first DC is returned as null. It is strange that when you navigate to the user properties in first DC, the LastLogon is set to 2/9/2014. It is clear that due to wrong values returned as 1/1/1601 the
condition in the main part of the script will never meet true for first DC.
I tested this code in a multi-domain environment but unfortunately I faced the same results.
Mahdi Tehrani Loves Powershell
Please kindly click on Propose As Answer or to mark this post as
and helpfull to other poeple.