List users in local admin group on all workstations

Question

Hi, I created a script that is supposed to query workstations and list all users in the local admin group. I originally used "test-connection" for logging purposes but it caused an issues when the computer responded but dns was incorrect for
that pc so i would get a false list of local admin members on that workstation. I changed to a wmi query instead and queried the system name using that so If the system name matched the workstation name being queried then write it is supposed to write to a
csv. For some reason, when i use $wmi.name as the variable, it does not work. What am i missing?
    $CurrentDate = Get-Date
    $CurrentDate = $CurrentDate.ToString('MM-dd-yyyy_hh-mm-ss')
    import-module activedirectory
     $servers= get-content "C:\Scripts\AD Audits\Local Admin\workstations.txt"
     $output = "c:\temp\local admin audit $CurrentDate.csv"
     $results = @()
     $servers | ForEach-Object{
    $wmi = gwmi win32_ComputerSystem -ComputerName $_ -ErrorAction SilentlyContinue
    $connected = Test-Connection $_ -Count 1 -Quiet -ErrorAction SilentlyContinue
    $state = if($wmi.name -eq '$_') {"$_ Verified"} else {"$_ did not respond"}
    $state | Out-File -Append "c:\temp\LocalAdmin log $CurrentDate.txt"
    $group =[ADSI]"WinNT://$_/Administrators,group"
    $members = $group.Members() | ForEach-Object {$_.GetType().InvokeMember("Name", 'GetProperty', $null, $_,   $null) }
    if($wmi)
       New-Object PSObject -Property @{
           DistinguishedName = (Get-ADComputer $_).DistinguishedName
           Server = $_
           Members = $members -join ";"
    } | Export-Csv $Output -NoTypeInformation

Answer 1

I agree use GP it is more reliable and easier to manage.
For the sake of demonstration of how this can be don here is how most of us would be likely todo this or a very close variation.
There is no issue with using Test-Connection and DNS.  AD/DNS cannot have the wrong names or your domain would crash.  Using Get-AdCOmputer instead of a file eliminates stale information.
$csvfile="c:\temp\local admin audit $([DateTime]::Now.ToString('MM-dd-yyyy_hh-mm-ss')).csv"
import-module activedirectory
#adjust Filter as needed
$adfilter='OperatingSystem -like "Windows 7*" -or OperatingSystem -like "Windows XP*"'
Get-AdComputer -Filter $adfilter |
ForEach-Object{
$props=@{
Server=$_.Name
IsAlive=$false
DistinguishedName=$_.DistinguishedName
Members=$null
if(Test-Connection $_.Name -Count 1 -Quiet){
$props.IsAlive=$true
$group =[ADSI]"WinNT://$($_.Name)/Administrators,group"
$members=$group.Members() |
ForEach-Object{
$_.GetType().InvokeMember("Name", 'GetProperty', $null, $_, $null)
$props.Members=$members -join ";"
New-Object PSObject -Property $props
} |
Export-Csv $csvfile -NoTypeInformation
Use GP and you won't have to be bothered with all of these techy details that usually require a Network Admin to sort out.
¯\_(ツ)_/¯