Windows DHCP Server Powershell Scripts

Disable all Scopes

# Deactivate ALL IPv4 DHCP scopes
# Run as Administrator

$DhcpServer = $env:COMPUTERNAME   # Change this if targeting a remote server

try {
    Import-Module DhcpServer -ErrorAction Stop

    Write-Host "Retrieving all scopes from $DhcpServer..." -ForegroundColor Cyan
    $scopes = Get-DhcpServerv4Scope -ComputerName $DhcpServer

    if (-not $scopes) {
        Write-Host "No scopes found." -ForegroundColor Yellow
        return
    }

    Write-Host "`nThe following scopes will be DEACTIVATED:" -ForegroundColor Yellow
    $scopes | Format-Table ScopeId, Name, State, StartRange, EndRange -AutoSize

    $confirm = Read-Host "`nAre you sure you want to deactivate ALL these scopes? (yes/no)"

    if ($confirm -ne "yes") {
        Write-Host "Aborted by user." -ForegroundColor Red
        return
    }

    Write-Host "`nDeactivating scopes..." -ForegroundColor Cyan

    foreach ($scope in $scopes) {
        try {
            Set-DhcpServerv4Scope -ComputerName $DhcpServer -ScopeId $scope.ScopeId -State InActive -ErrorAction Stop
            Write-Host "  ✓ Deactivated: $($scope.ScopeId) ($($scope.Name))" -ForegroundColor Green
        }
        catch {
            Write-Host "  ✗ Failed: $($scope.ScopeId) - $($_.Exception.Message)" -ForegroundColor Red
        }
    }

    Write-Host "`nDone. Current status:" -ForegroundColor Cyan
    Get-DhcpServerv4Scope -ComputerName $DhcpServer | 
        Select-Object ScopeId, Name, State | 
        Format-Table -AutoSize
}
catch {
    Write-Host "Error: $($_.Exception.Message)" -ForegroundColor Red
}

Export all active leases

# Export all current IPv4 DHCP leases (no ScopeId prompt)
# Run as Administrator

$DhcpServer = $env:COMPUTERNAME   # Change this if running against a remote server
$ExportPath = "C:\Temp\DHCP_IPv4_Leases_$(Get-Date -Format 'yyyy-MM-dd_HHmm').csv"

try {
    Import-Module DhcpServer -ErrorAction Stop

    Write-Host "Getting all scopes from $DhcpServer..." -ForegroundColor Cyan

    $allLeases = @()

    Get-DhcpServerv4Scope -ComputerName $DhcpServer | ForEach-Object {
        Write-Host "  → Retrieving leases for scope $($_.ScopeId) ($($_.Name))" -ForegroundColor Gray

        $leases = Get-DhcpServerv4Lease -ComputerName $DhcpServer -ScopeId $_.ScopeId -ErrorAction SilentlyContinue
        if ($leases) {
            $allLeases += $leases
        }
    }

    if ($allLeases.Count -gt 0) {
        $allLeases |
            Select-Object IPAddress,
                          ScopeId,
                          ClientId,
                          HostName,
                          AddressState,
                          LeaseExpiryTime,
                          ClientType,
                          Description,
                          DnsRegistration,
                          DnsName |
            Sort-Object ScopeId, IPAddress |
            Export-Csv -Path $ExportPath -NoTypeInformation -Encoding UTF8

        Write-Host "`nSuccessfully exported $($allLeases.Count) leases to:" -ForegroundColor Green
        Write-Host $ExportPath -ForegroundColor Yellow
    }
    else {
        Write-Host "No leases found." -ForegroundColor Yellow
    }
}
catch {
    Write-Host "Error: $($_.Exception.Message)" -ForegroundColor Red
}

Change Gateways

How to change the gateways on all DHCP scopes within 10.160.0.0/16 from .1 to .254

# =============================================
# Change Default Router (.1 -> .254) in DHCP Scopes
# Target: scopes inside 10.160.0.0/16
# =============================================

# Get all IPv4 scopes
$scopes = Get-DhcpServerv4Scope

foreach ($scope in $scopes) {
    $network = $scope.ScopeId.IPAddressToString
    
    # Check if the scope is inside 10.160.0.0/16
    if ($network -like "10.160.*") {
        
        # Get current Router option (003) for this scope
        $routerOption = Get-DhcpServerv4OptionValue `
                          -ScopeId $scope.ScopeId `
                          -OptionId 3 -ErrorAction SilentlyContinue
        
        if ($routerOption -and $routerOption.Value) {
            $oldRouter = $routerOption.Value[0]   # usually only one value
            
            # Replace last octet .1 with .254
            if ($oldRouter -like "*.*.*.1") {
                $newRouter = $oldRouter -replace "\.1$", ".254"
                
                Write-Host "Scope $network : Changing router from $oldRouter to $newRouter" -ForegroundColor Green
                
                # Apply the change
                Set-DhcpServerv4OptionValue `
                    -ScopeId $scope.ScopeId `
                    -OptionId 3 `
                    -Value $newRouter `
                    -Force
            }
            else {
                Write-Host "Scope $network : Router is $oldRouter (not ending in .1) - skipped" -ForegroundColor Yellow
            }
        }
        else {
            Write-Host "Scope $network : No Router option configured" -ForegroundColor Yellow
        }
    }
}

Write-Host "Finished processing scopes in 10.160.0.0/16" -ForegroundColor Cyan