What is the best way to get computer's domain into a variable?

Please see here: http://blog.riccardocelesti.it/find-computer-name-and-domain-using-powershell/


(Get-WmiObject Win32_ComputerSystem).Domain

$domainDNS = (Get-WmiObject -Query "SELECT Domain FROM Win32_ComputerSystem").Domain
$domainNB = (Get-WmiObject -Query "Select DomainName FROM Win32_NTDomain  WHERE DnsForestName='$($domainDNS)'").DomainName

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Just for something completely different, here's how we used to do it in vbScript (but in PowerShell):

$obj = New-Object -ComObject ADSystemInfo
$type = $obj.GetType()
$domainDNS = $type.InvokeMember( 'DomainDNSName', 'GetProperty', $null, $obj, $null )
$domainNB = $type.InvokeMember( 'DomainShortName', 'GetProperty', $null, $obj, $null )
$obj = $type = $null

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get-addomain commands worked best.

This didn't give me any output

PS Env:\> $domainNB = (Get-WmiObject -Query "Select DomainName FROM Win32_NTDomain  WHERE DnsForestName='$($domainDNS)'").DomainName

PS Env:\> $domainNB


this worked but only for FQDN and not NETBIOS. what would be the NB command? I didn't see NB name when I did the following:
Get-WmiObject Win32_ComputerSystem | select *


This looks like too much code if you can just use one line ;) Why would you use all those?

$obj = New-Object -ComObject ADSystemInfo
$type = $obj.GetType()
$domainDNS = $type.InvokeMember( 'DomainDNSName', 'GetProperty', $null, $obj, $null )
$domainNB = $type.InvokeMember( 'DomainShortName', 'GetProperty', $null, $obj, $null )
$obj = $type = $null

Nothing wrong with Get-AdDomain - however, it requires the Active Directory RSAT tools to be installed. Perhaps someone should've asked that question, but it's not an assumption that should be made for everyone's workstation. Few people will have it installed. It'll even be installed on few servers. :-)

Here is the proper other query:

$domainNB = ( Get-WMIObject Win32_NTDomain |? { $_.Status -eq 'OK' -and $_.DomainName } ).DomainName

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Ah, I see now what @oBdA was doing, for multi-domain forests what he wrote should work.

That
$domainNB = (Get-WmiObject -Query "Select DomainName FROM Win32_NTDomain  WHERE DnsForestName='$($domainDNS)'").DomainName
obviously only works if you run the other command first, since it uses the domain's DNS name::
$domainDNS = (Get-WmiObject -Query "SELECT Domain FROM Win32_ComputerSystem").Domain
And then it works just fine.
Why more than one line? Because your question sounded like you needed a generally available solution, not one that requires that the ActiveDirectory module is installed (which, as Michael already pointed out), in most cases isn't.

Michael,
that's not really the "proper" query - Win32_NTDomain returns trusted domains as well, plus one for the local machine if run on a member server.
it will return multiple results if there's a trust with another domain.

I corrected myself. :-)

I think smth wrong with the quotes here. Maybe that is why I am not getting anything back. Sorry. I am newby.
Could you please correct.
Then it is makes sense since it doesn't require AD module.
thank you so much for expanding on this

'$($domainDNS)'").DomainName

$domainNB = (Get-WmiObject -Query "Select DomainName FROM Win32_NTDomain  WHERE DnsForestName='$($domainDNS)'").DomainName

There's nothing wring with the quotes. Copy and paste exactly as it is.

$domainDNS = (Get-WmiObject -Query "SELECT Domain FROM Win32_ComputerSystem").Domain
$domainNB = (Get-WmiObject -Query "SELECT DomainName FROM Win32_NTDomain WHERE DnsForestName='$($domainDNS)'").DomainName

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Here's what happens with those quotes:

"SELECT DomainName FROM Win32_NTDomain WHERE DnsForestName='$($domainDNS)'"
^                                                          ^             ^^
+-- Opening string (WQL Query)                             |             |+-- Closing string (WQL query)
                                                           |             +--- Closing search string inside WQL query
                                                           +----------------- Opening search string inside WQL query

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