DHCP-Option 12 missing after DHCP-Server restart

Question

We are using DHCP-Reservation to provide an IP-adress to our clients. Additional we use the DHCP-Option 12 to handle the Hostname of the client.

The DHCP-reservation (including the option12) were set within a powershell script to decrease the manual tasks.
We noticed, that the DHCP-Option 12 of IP-Reservation (which was set with the command "Set-DhcpServerv4OptionValue") will be resetted after a restart of the DHCP-Server.
Note: when you do this step manually within the GUI, the problem does not occure.

Summarized: setting the option 12 to a DHCP-Reservation with command "Set-DhcpServerv4OptionValue", will be resetted after restarting the DHCP-Services.
Can anyone provide me a workaround or does anyone have a idea how I can solve the issue?

Attached you can find a short Powershell-Snippet which you can use to reproduce the problem:

Blockquote

Ensure that you have a IP-Scope with 192.168.10.0

$ipscope = "192.168.10.0"
$ipscope_start = "192.168.10.1"
$ipscope_end = "192.168.10.254"
$ipscope_subnetmask = "255.255.255.0"
[ipaddress]$ip = "192.168.10.18" #Mention your IP-Adress you want to test
$DHCPServer = "TEMPLATE_W2K16" #Mention the Servername of your testserver

Add-DhcpServerv4Scope -ComputerName $DHCPServer -StartRange $ipscope_start -EndRange $ipscope_end -Name $ipscope -SubnetMask $ipscope_subnetmask
Add-DhcpServerv4Reservation -ComputerName $DHCPServer -ScopeId $ipscope -IPAddress $ip -ClientId "11-22-33-44-55-66" -Name "Initialname"

For($i=0; $i -le 5;$i++)
{
$reservationname = "Name$i"
Set-DhcpServerv4Reservation -IpAddress $ip -ClientId 11-22-33-44-55-66 -Name $reservationname -Description $reservationname -Type Dhcp -ComputerName $DHCPServer
Set-DhcpServerv4OptionValue -ReservedIP $ip -OptionId 12 -Value $reservationname -ComputerName $DHCPServer
$OptionValue1 = Get-DhcpServerv4OptionValue -ReservedIP $Ip -ComputerName $DHCPServer
Write-host "Current Option: $($OptionValue1.Value)"
Read-host "Restart DHCP-Service?"
Restart-Service DHCPServer
sleep -Seconds 5
$OptionValue2 = Get-DhcpServerv4OptionValue -ReservedIP $Ip -ComputerName $DHCPServer
Write-Host "Option12 we want to set: $reservationname"
Write-host "Option12 after restart: $($OptionValue2.Value)"
Read-host "Next try?"
}

Answer 1

Well, that is just bonkers! The value changes in the MMC but it's lost after restarting the service. Looks like a bug to me!

You can try this as a work-around. The Remove-DhcpServerv4OptionValue will fail in the 1st iteration because I didn't bother to set it outside the loop, but it's just a demo so don't let it bother you:

#Ensure that you have a IP-Scope with 192.168.10.0
$ipscope = "192.168.10.0"
$ipscope_start = "192.168.10.1"
$ipscope_end = "192.168.10.254"
$ipscope_subnetmask = "255.255.255.0"
[ipaddress]$ip = "192.168.10.18" #Mention your IP-Adress you want to test
$DHCPServer = "SRV02" #Mention the Servername of your testserver

Add-DhcpServerv4Scope -ComputerName $DHCPServer -StartRange $ipscope_start -EndRange $ipscope_end -Name $ipscope -SubnetMask $ipscope_subnetmask
Add-DhcpServerv4Reservation -ComputerName $DHCPServer -ScopeId $ipscope -IPAddress $ip -ClientId "11-22-33-44-55-66" -Name "Initialname"

For ($i = 0; $i -le 5; $i++) {
    Remove-DhcpServerv4OptionValue -ComputerName $DHCPServer -OptionID 12 -ReservedIP $ip
    Remove-DhcpServerv4Reservation -ComputerName $DHCPServer -ReservedIP $IP

    $reservationname = "Name$i"

    Add-DhcpServerv4Reservation -ComputerName $DHCPServer -ScopeId $ipscope -IPAddress $ip -ClientId "11-22-33-44-55-66" -Name $reservationname -Description $reservationname -Type Dhcp
    Set-DhcpServerv4OptionValue -ReservedIP $ip -OptionId 12 -Value $reservationname -ComputerName $DHCPServer

    $OptionValue1 = Get-DhcpServerv4OptionValue -ReservedIP $Ip -ComputerName $DHCPServer  # may return options 12 and 81
    Write-Host "Current Option: $($OptionValue1.Value)"
    Read-Host "Restart DHCP-Service?"
    Restart-Service DHCPServer
    sleep -Seconds 5
    $OptionValue2 = Get-DhcpServerv4OptionValue -ReservedIP $Ip -ComputerName $DHCPServer
    Write-Host "Option12 we want to set: $reservationname"
    Write-Host "Option12 after restart: $($OptionValue2.Value)"
    Read-Host "Next try?"
}

Answer 2

Add some error handling around that option value setting:

Try{
    Set-DhcpServerv4OptionValue -ReservedIP $ip -OptionId 12 -Value $reservationname -ComputerName $DHCPServer -ErrorAction STOP
}
Catch{
    Throw $_
}

The setting of the option value requires that the option has already been defined, but I don't see that in your code (Set-DhcpServerv4OptionDefinition).
From the help for the Set-DhcpServerv4OptionValue cmdlet: "The definition for the option must already exist."

Answer 3

Hi,

Thanks for posting in Q&A platform.

I will reproduce this issue in my environment and keep you posted if any update.

Please try to configure this Option 12 from GUI and restart to see if the issue still existed.

Best Regards,
Sunny

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