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DHCP Server Settings

If you do not use FOG to provide DHCP services in your network (which is a very common and completely supported configuration), then you need to configure the existing DHCP server to use fog as the tftp server to get the pxe boot files from, and you need to configure what boot file to use.


If you do not have access to your DHCP server, or are using a device that isn't capable of specifying option 066 and 067 (next server and file name) you can use ProxyDHCP instead
The most popular ProxyDHCP method with fog is dnsmasq. This article will walk you through that: Proxy DHCP with DNSMasq

These two DHCP options must be set:

Option 66

Set Option 66, also called 'Boot Server', 'Next server' or 'TFTP Server' to the IP address or hostname of the FOG server.

Option 67

Set option 67, also called 'Bootfile Name' to the ipxe boot file that works best in your environment.
For modern UEFI environments, either of these files have the best compatibility (you simply enter this file name into the dhcp setting)

  • snponly.efi
  • ipxe.efi

Most newer clients will be able to boot with one of the efi boot files above, but older hardware models that do not have UEFI support and only support legacy BIOS firmware will not boot.


If you have a mixed environment see Bios and UEFI Co-Existence

For older legacy models, these are the boot files to set

  • undionly.kpxe
  • undionly.kkpxe
  • ipxe.kpxe
  • ipxe.kkpxe

You can find other pxe boot files in you /tftpboot directory on your fogserver.

Examples of DHCP server configurations

The below are some examples with screen shots on how to configure these settings in some servers.
The screenshots are a bit old but the general idea is still the same on modern versions

Windows Server DHCP

Setting the options with powershell

This little powershell snippet will get all your dhcp server scopes and set option 66 and option 67 to the values you input into the script.


This requires the dhcp module that is installed on a server when the dhcp role is added. You can also add it to your windows workstation machine by installing rsat tools, and of course it also requires admin privileges to manage the dhcp server options.
This script will set the options at the scope/subnet levels rather than at a global server level

#define your dhcp server hostname or ip
$dhcpSvr = 'dhcp.yourDomain.tld'
#define your fog server fqdn, hostname, or ip
$fogAddr = 'fogserver.yourDomain.tld'
#define you pxe boot file
$pxeBootFile = 'snponly.efi'

#get all the scopes from the main dhcp server and expand to the nested ipAddressToString property of the scopeIDs to get a string array of scope ids`

$scopes = (Get-DhcpServerv4Scope -ComputerName $dhcpSvr).scopeID.ipaddresstostring

#loop through all dhcp scopes and add the options
$scopes | Foreach-object {
    $dhcpOptions = @{
        ComputerName = $dhcpSvr;
        ScopeId = $_
    Set-DhcpServerv4OptionValue @dhcpOptions -OptionID 66 -value $fogAddr;
    Set-DhcpServerv4OptionValue @dhcpOptions -OptionID 67 -value $pxeBootFile;

Setting the options in the dhcp console

You can get to the server or scope options of your dhcp server in dhcpmgmt.msc and set them like so

  • Option 66


This can be the ip address, hostname, of fully qualified domain name (fqdn) of your fog server.


  • Option 67

Novell (Linux) Server DHCP

Last update: 2023-07-23