Скрипт Replace-DNSAddressOnDHCPScopes позволяющий поменять на одном или нескольких серверах DHCP параметр "006 DNS Servers".

Допустим у нас есть два сервера динамического распределения узлов DHCP. На каждом из этих серверов порядка сотни областей Scope. Каждая область Scope содержит параметры DNS серверов в своем определенном порядке, которые будут выдаваться клиентам.
Понадобилось нам перенести один или все наши сервера DNS с изменением их IP-адресов. И чтобы затем не пришлось вручную изменять на каждом DHCP сервере, в каждой области Scope, несколько параметров DNS, я предлагаю воспользоваться моим скриптом.

Как им пользоваться:

PS C:\> Get-Help Replace-DNSAddressOnDHCPScopes -Examples

Function Global:Replace-DNSAddressOnDHCPScopes ([parameter(Position=0, Mandatory=$true, ValueFromPipeline=$false)][array]$DHCPservers,
                                                [parameter(Mandatory=$true)][string]$DNSserverWhichReplace,
                                                [parameter(Mandatory=$true)][string]$DNSserverReplaceOn)

{

<#
    .SYNOPSIS
    Replace DNS server parameter in each Scope of selected DHCP servers.

    .DESCRIPTION
    This function replaces on the selected DHCP servers a specified DNS server parameter to the new one.

    .PARAMETER DHCPservers
    Specify your DHCP servers.

    .PARAMETER DNSserverWhichReplace
    Specify old DNS server, which will be replaced.

    .PARAMETER DNSserverReplaceOn
    Specify new DNS server.

    .EXAMPLE
    PS C:\> Replace-DNSAddressOnDHCPScopes -DHCPservers dc1.domain.local,dc2.domain.local -DNSserverWhichReplace 192.168.1.2 -DNSserverReplaceOn 10.0.1.2

    .EXAMPLE
    PS C:\> Replace-DNSAddressOnDHCPScopes -DHCPservers dc1.domain.local,dc2.domain.local -DNSserverWhichReplace 192.168.1.2 -DNSserverReplaceOn 10.0.1.2 -Verbose
#>

    Import-Module -Name DhcpServer -ErrorAction Stop

    $IPregex='(?<Address>((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?))'

    if ($DNSserverWhichReplace -notmatch $IPregex)
    {
        Write-Error -Message "Old DNS server address, which would be replaced, has been specified incorrectly" -RecommendedAction "Type the valid IP address of DNS server"
        Break
    }

    if ($DNSserverReplaceOn -notmatch $IPregex)
    {
        Write-Error -Message "New DNS server address, which would replace the old one, has been specified incorrectly" -RecommendedAction "Type the valid IP address of DNS server"
        Break
    }


    $Error.Clear | Out-Null
    Write-Host
    Write-Host
    Write-Host 'Original and comments: http://vam.in.ua/index.php/it/25-ms-powershell/240-powershell-replace-dns-on-dhcpscopes.html' -ForegroundColor DarkCyan
    Write-Host 'Feedback: http://vam.in.ua/index.php/contacts/2-admins/1-aleksey.html' -ForegroundColor DarkCyan
    Write-Host

    $CurrentDHCPserver = 0

    foreach ($DHCPserver in $DHCPservers)
    {
        $CurrentDHCPserver += 1
        $TotalDHCPservers = $DHCPservers.Count

        $CountChangedScopes = 0
        $CountChangedDNSservers = 0

        [array]$DHCPScopes = ''
        $DHCPScopes = (Get-DHCPserverv4Scope -ComputerName $DHCPserver).ScopeId.IPAddressToString
        if (($DHCPScopes -eq '') -or ($DHCPserver -eq $null))
        {
            Continue
        }

        [string]$ProgressActivity = "Processing on DHCP server $DHCPserver ($CurrentDHCPserver of $TotalDHCPservers specified)"
        [int32]$CurrentScope = 0

        foreach ($Scope in $DHCPScopes)
        {
            $CurrentScope += 1
            [int32]$ProgressPercent = $CurrentScope * 100 / ($DHCPScopes.Count)
            Write-Progress -Activity $ProgressActivity -Status "Please wait..." -PercentComplete $ProgressPercent

            $OptionDnsServersOfScope = (Get-DHCPserverv4OptionValue -ComputerName $DHCPserver -OptionId 6 -ScopeId $Scope).Value # Получаем текущие записи DNS серверов 

            $SetOptionDnsServersOfScope = @() # Объявляем массив для нового набора DNS серверов

            $NeedReplace = $false

            foreach ($DNSServerOption in $OptionDnsServersOfScope)
            {
                if ($DNSServerOption -eq $DNSserverWhichReplace) 
                {
                    $SetOptionDnsServersOfScope += $DNSserverReplaceOn
                    $NeedReplace = $true
                    $CountChangedDNSservers += 1
                    Write-Verbose "Change was applied in Scope $Scope at server $DHCPserver"
                }
                else
                {
                    $SetOptionDnsServersOfScope += $DNSServerOption
                }
            }

            if ($NeedReplace -eq $true) 
            {
                Set-DHCPserverv4OptionValue -ComputerName $DHCPserver -DnsServer $SetOptionDnsServersOfScope -ScopeId $Scope
                $CountChangedScopes += 1
            }
        }
    
    Write-Host "There were $CountChangedDNSservers changes in $CountChangedScopes Scopes on Server $DHCPserver" -ForegroundColor DarkGray
    }

    Write-Host 
    Write-Host "Everything was done!" -ForegroundColor DarkGray
}