Passing option-209 to PXE client w/ ISC DHCPD 2.0pl5

Glenn Satchell Glenn.Satchell at
Mon Dec 10 17:08:45 UTC 2007

In version 3 you can set dhcp-parameter-request-list to a comma
separated list of option numbers. Don't know if this works in version
2, but it is in the dhcp-options man page.

     option dhcp-parameter-request-list uint16;

       This option, when sent  by  the  client,  specifies  which
       options  the  client  wishes  the server to return.   Nor-
       mally, in the ISC DHCP client,  this  is  done  using  the
       request  statement.    If  this option is not specified by
       the client, the DHCP server  will  normally  return  every
       option  that  is  valid  in  scope  and that fits into the
       reply.   When this option is specified on the server,  the
       server  returns  the specified options.   This can be used
       to  force  a  client  to  take  options  that  it   hasn't
       requested,  and it can also be used to tailor the response
       of the DHCP server for clients that may need a  more  lim-
       ited  set  of options than those the server would normally

I hope this is useful...


>Date: Mon, 10 Dec 2007 08:44:44 -0800
>From: "Craig Johnston" <agspoon at>
>To: dhcp-users at
>Subject: Passing option-209 to PXE client w/ ISC DHCPD 2.0pl5
>Does anyone remember if there is a way to coerce the ISC DHCPD version
>2 (2.0pl5) to send options to a PXE client that does not explicitly
>request them.  I can do this in version 3 of DHCPD via the
>vendor-option-space mechanism, but this is not available in version 2
>of the server (the version my network switch uses).
>I want to be able to specify the PXE filename via option 209 (plus
>option 208 to enable it).  I know how to set the option (option
>option-209 "myfile";), but the server will not return these parameters
>to the PXE client as they are not specifically requested.

More information about the dhcp-users mailing list