DHCP Server¶

# Read DHCP Server parameters
Get-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\DHCPServer\Parameters" |
    Select-Object DatabasePath, DatabaseName, BackupDatabasePath, BackupInterval

# Check if DHCP Server role is installed
Get-WindowsFeature -Name DHCP | Select-Object Name, InstallState

# List all DHCP scopes
Get-DhcpServerv4Scope | Select-Object ScopeId, Name, SubnetMask, StartRange, EndRange, State |
    Format-Table -AutoSize

# Create a new DHCP scope
Add-DhcpServerv4Scope -Name "LAN-Marseille" `
    -StartRange 192.168.3.100 -EndRange 192.168.3.250 `
    -SubnetMask 255.255.255.0 -LeaseDuration 8.00:00:00 `
    -State Active

# Add an exclusion range
Add-DhcpServerv4ExclusionRange -ScopeId 192.168.3.0 `
    -StartRange 192.168.3.240 -EndRange 192.168.3.250

# Create a DHCP reservation
Add-DhcpServerv4Reservation -ScopeId 192.168.1.0 `
    -IPAddress 192.168.1.50 -ClientId "AA-BB-CC-DD-EE-FF" `
    -Name "PRINTER-RDC" -Description "Imprimante rez-de-chaussee"

# List all reservations in a scope
Get-DhcpServerv4Reservation -ScopeId 192.168.1.0 |
    Select-Object IPAddress, ClientId, Name | Format-Table -AutoSize

# Check scope utilization
Get-DhcpServerv4ScopeStatistics -ScopeId 192.168.1.0

# Create a failover relationship (load balance mode)
Add-DhcpServerv4Failover -Name "Paris-Failover" `
    -PartnerServer "DHCP02.corp.local" `
    -ScopeId 192.168.1.0 `
    -SharedSecret "S3cur3P@ssw0rd!" `
    -LoadBalancePercent 50 `
    -MaxClientLeadTime 01:00:00 `
    -AutoStateTransition $true `
    -StateSwitchInterval 00:30:00

# Check failover status
Get-DhcpServerv4Failover | Select-Object Name, Mode, State, PartnerServer,
    LoadBalancePercent | Format-Table -AutoSize

# Force replication of failover scopes to partner
Invoke-DhcpServerv4FailoverReplication -Name "Paris-Failover" -Force

# Set server-level DNS options
Set-DhcpServerv4OptionValue -OptionId 6 -Value "192.168.1.10","192.168.1.11"
Set-DhcpServerv4OptionValue -OptionId 15 -Value "corp.local"

# Set scope-level options (override server-level)
Set-DhcpServerv4OptionValue -ScopeId 192.168.1.0 -OptionId 3 -Value "192.168.1.1"
Set-DhcpServerv4OptionValue -ScopeId 192.168.1.0 -OptionId 6 -Value "192.168.1.10","192.168.1.11"
Set-DhcpServerv4OptionValue -ScopeId 192.168.1.0 -OptionId 51 -Value 691200

# Set lease duration to 8 hours for a scope
Set-DhcpServerv4Scope -ScopeId 192.168.1.0 -LeaseDuration 08:00:00

# Check audit logging status
Get-DhcpServerAuditLog

# Read today's DHCP audit log
$day = (Get-Date).ToString("ddd", [System.Globalization.CultureInfo]::InvariantCulture)
$logFile = "C:\Windows\System32\dhcp\DhcpSrvLog-$day.log"
Get-Content $logFile -Tail 20

# Verify backup exists
Get-ChildItem -Path "C:\Windows\System32\dhcp\backup" -Recurse |
    Select-Object Name, LastWriteTime, Length | Format-Table -AutoSize

# Create a manual backup
Backup-DhcpServer -Path "D:\DHCP-Backup\$(Get-Date -Format 'yyyy-MM-dd')"

# Export full DHCP configuration (scopes, reservations, options)
Export-DhcpServer -File "D:\DHCP-Backup\dhcp-export.xml" -Leases

# Check DHCP service status
Get-Service DHCPServer | Select-Object Name, Status, StartType

# Check database file integrity
$dbPath = (Get-ItemPropertyValue -Path "HKLM:\SYSTEM\CurrentControlSet\Services\DHCPServer\Parameters" `
    -Name "DatabasePath")
$dbFile = Join-Path $dbPath "dhcp.mdb"

[PSCustomObject]@{
    Path   = $dbFile
    Exists = Test-Path $dbFile
    Size   = if (Test-Path $dbFile) { (Get-Item $dbFile).Length } else { "N/A" }
}

# Step 1: Stop the DHCP service (if not already stopped)
Stop-Service DHCPServer -Force -ErrorAction SilentlyContinue

# Step 2: Verify that the backup exists
$backupPath = Get-ItemPropertyValue `
    -Path "HKLM:\SYSTEM\CurrentControlSet\Services\DHCPServer\Parameters" `
    -Name "BackupDatabasePath"
Get-ChildItem -Path $backupPath -Recurse | Select-Object Name, LastWriteTime, Length

# Step 3: Set the restore flag in registry
Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\DHCPServer\Parameters" `
    -Name "RestoreFlag" -Value 1 -Type DWord

# Verify the flag is set
Get-ItemPropertyValue -Path "HKLM:\SYSTEM\CurrentControlSet\Services\DHCPServer\Parameters" `
    -Name "RestoreFlag"

# Step 4: Start the DHCP service (it will restore from backup automatically)
Start-Service DHCPServer

# Verify service is running
Get-Service DHCPServer | Select-Object Name, Status

# Verify RestoreFlag is back to 0
Get-ItemPropertyValue -Path "HKLM:\SYSTEM\CurrentControlSet\Services\DHCPServer\Parameters" `
    -Name "RestoreFlag"

# Verify scopes are back
Get-DhcpServerv4Scope | Select-Object ScopeId, Name, State | Format-Table -AutoSize

# Restore from XML export
Import-DhcpServer -File "D:\DHCP-Backup\dhcp-export.xml" -BackupPath "D:\DHCP-Backup\pre-import" `
    -Leases -ScopeOverwrite -Force

# Authorize the DHCP server in AD (if needed after rebuild)
Add-DhcpServerInDC -DnsName "DHCP01.corp.local" -IPAddress "192.168.1.5"

# Verify authorization
Get-DhcpServerInDC

# Force a scope reconcile to fix inconsistencies
Repair-DhcpServerv4IPRecord -ScopeId 192.168.1.0 -Force