Delete and Add Entries to DNS Suffixes

Question

Via a command line argument or PowerShell I want to manipulate the following list:

If you're wondering why, it's because a very specific VPN sets this to the client's domain when you connect, but never removes it. It breaks all my local access and it always replaces ALL entries within the list, it doesn't just add to it.

I've tried registry settings that I've discovered, like adding to the searchlist in HKLM\System\currentcontrolset\services\tcpip\parameters

I've tried flushing my dns, resetting the network adapter.

I've tried looking for other registry keys, editing adapter specific dns suffixes.

None of that appears to have an actual impact on this list, and yet, somehow that VPN client is ruining my network connections each time I use it.

The existing questions here on SU don't address this. Everything addresses the previously mentioned points, but not the values within this actual box. I've tried every variation with ZERO impact so far.

Answer 1

Important: Run these methods from an administrator elevated environment/shell/command prompt.

1. Simply run Set-DnsClientGlobalSetting -SuffixSearchList @("") to remove all DNS suffixes entirely.

2. With some PowerShell logic you can...

   • set the DNS name(s) to be excluded from the configuration list
   • run conditional logic in a loop and use a -notin comparison operator to set and append an [array] variable using the += assignment operator to build a list omiting the excluded DNS name
   • finally use the new list variable as the argument value to pass in with the Set-DnsClientGlobalSetting -SuffixSearchList @($nList); command

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PowerShell Script

$ExcldDomain = "myDomain.com";                      ## Set excluded domain(s)
$s = (Get-DnsClientGlobalSetting).SuffixSearchList; ## Get current suffixes

$nList = @();
$s | % {If($_ -notin $ExcldDomain){[array]$nList += [array]$_}};

Stop-Service -Name "SONICWALL_NetExtender" -Force;
Set-DnsClientGlobalSetting -SuffixSearchList @($nList);

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Supporting Resources

• Get-DnsClientGlobalSetting

• Set-DnsClientGlobalSetting

  -SuffixSearchList

  Specifies a list of global suffixes that can be used in the specified order by the DNS client for resolving the IP address of the computer name. These suffixes are appended in the specified order to resolve the computer name that is specified. This parameter value cannot be set if the suffix search list setting is already deployed through Group Policy.

• About Comparison Operators

• About Assignment Operators

  += Increases the value of a variable by the specified value, or appends the specified value to the existing value.

Answer 2

At least on Windows 10 21H2, the following does not work to remove all DNS suffixes

Set-DnsClientGlobalSetting -SuffixSearchList @("")

but this does

Set-DnsClientGlobalSetting -SuffixSearchList @('.')

and so does this

Set-DnsClientGlobalSetting -SuffixSearchList '.'

I have tried variations of empty strings and the period/dot, with single and double quotes, and found that the ones that works consistently are the ones in the code snippets above.

You can verify the effects yourself by using the following command

Get-DnsClientGlobalSetting