Multiple IP Addresses for a single MAC address

Simon Hobson dhcp1 at
Wed Sep 5 19:43:02 UTC 2007

daniel.bender at wrote:
>Can anyone shed some light on the following problem we are encountering?

Sigh, check the archives, look for PXE - it comes up and is explained 
every few months.

In short, your OS (Windows I assume) supplies a client-id whilst PXE 
Boot doesn't - therefore they are (as far as the DHCP Server is 
concerned different clients and are given different addresses. This 
is in accordance with the RFC.

The primary database key is the client-id if supplied, if (and only 
if) client-id is not supplied then the MAC address is used.

In a future version it is planned to allow the administrator to 
change the key selection used, so he can if desired configure the 
server to ignore the client-id. Until then, this is the best I can 
offer :

>Date: Tue, 12 Dec 2006 07:43:57 +0200
>From: Yedidyah Bar-David <didi at>
>To: dhcp-users at
>Subject: Re: status update
>On Mon, Dec 11, 2006 at 04:35:15PM -0500, SCOTT BURGIN wrote:
>  > Hello.  Running V3.0.4 server on RHEL.
>  >
>  > We have a remote site using PXE to image workstations.
>  > What we're seeing is the initial PXE boot (with a certain uid) is
>  > causing a lease to be written to the leases file as active.
>  > After the image is laid down and the machine boots the second time, the
>  > machine sends another Discover using a different uid, getting a
>  > different lease.
>  >
>  > I understand this is correct behavior per RFC, but have read that this
>  > is widely acknowledged to be an implementation PIA.
>  > What's fuzzy to me after searching the archives is what everyone agrees
>  > to be options currently to this dilemna for me.
>  > I've heard of patches, but can't seem to find them...other options ?

More information about the dhcp-users mailing list