Tag Archives: network management

Automating DHCP Scope Option Removal with PowerShell

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If you’re managing a large network with multiple DHCP servers, you know how tedious it can be to manually remove DHCP scope options. Fortunately, PowerShell can help automate the process and make network management much more efficient. In this post, we’ll walk you through a PowerShell function that can remove DHCP scope options with just a few lines of code.

The “Remove-DhcpScopeOptions” Function

The “Remove-DhcpScopeOptions” function takes two parameters: the name of the DHCP server and a switch for the “-WhatIf” parameter. The “-WhatIf” parameter allows you to see what the function would do without actually making any changes.

function Remove-DhcpScopeOptions {
  [CmdletBinding(SupportsShouldProcess=$true)]
  param (
    [Parameter(Mandatory=$true)]
    [string]$ComputerName,
    [switch]$WhatIf
  )

  # Get all DHCP scopes on the server
  $scopes = Get-DhcpServerv4Scope -ComputerName $ComputerName

  # Get all options for the DHCP server
  $serverOptions = Get-DhcpServerv4OptionValue -ComputerName $ComputerName

  # For each scope, get the options and compare them to the server-level options
  foreach ($scope in $scopes) {
    $scopeOptions = Get-DhcpServerv4OptionValue -ScopeId $scope.ScopeId -ComputerName $ComputerName

    # For each option in the scope, check if it exists at the server level with the same value
    foreach ($option in $scopeOptions) {
      $serverOption = $serverOptions | Where-Object { $_.OptionId -eq $option.OptionId }
      if ($serverOption -ne $null -and $serverOption.Value -eq $option.Value) {
        # If the option exists at the server level with the same value, remove it from the scope
        if ($WhatIf) {
          Write-Host "What if: Removing option $($option.OptionId) from scope $($scope.ScopeId) on DHCP server $ComputerName."
        } else {
          Remove-DhcpServerv4OptionValue -ScopeId $scope.ScopeId -OptionId $option.OptionId -ComputerName $ComputerName -Confirm:$false
        }
      }
    }
  }

  # Replicate the scopes to all DHCP servers in the enterprise
  if (!$WhatIf) {
    Invoke-DhcpServerv4ReplicateScopes -ComputerName $ComputerName
  }
}

How it Works

The “Remove-DhcpScopeOptions” function works by first getting all DHCP scopes on the server using the “Get-DhcpServerv4Scope” cmdlet. It stores the results in the $scopes variable. It then gets all options for the DHCP server using the “Get-DhcpServerv4OptionValue” cmdlet and stores the results in the $serverOptions variable.

For each DHCP scope, the function gets the options using the “Get-DhcpServerv4OptionValue” cmdlet and stores the results in the $scopeOptions variable. It then compares the options in each scope to the server-level options and removes any options that exist at the server level with the same value. Finally, the function replicates the scopes to all DHCP servers in the enterprise.

Example

Remove-DhcpScopeOptions -ComputerName "dhcpserver01" -WhatIf
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