Win XP discover/offer/req/ack loop (Help!)

Sebastian Hagedorn Hagedorn at
Mon Aug 28 09:35:46 UTC 2006


--On 24. August 2006 16:31:28 -0400 "Jeff A. Earickson" 
<jaearick at> wrote:

> This smells like a bug to me, maybe in DHCP, maybe in a router setting,
> maybe a rogue DHCP server on the affected subnet, maybe in Windoze.
> I just upgraded to 3.0.5rc1 on both my primary and failover.  Then I
> watched the traffic from my problem subnet.  Observe the behavior for
> one MAC, probably a Windoze box:
> 1) DHCPREQUEST for ( from 00:14:38:9d:ce:0d
> via wrong network.
> The machine thinks it is on a 192.168 address and makes a DHCP request
> in that space.  I think our routers are configured to drop unroutable
> addresses like 192.168 on the floor.  But the dhcp helper on the router
> at at least passed along the bogus request to the ISC DHCP
> server.
> 2) DHCPNAK on to 00:14:38:9d:ce:0d via
> The ISC DHCP server says "no way", rightly so.
> 3) DHCPDISCOVER from 00:14:38:9d:ce:0d via
>     DHCPOFFER on to 00:14:38:9d:ce:0d via
> The Windoze box comes back to discover what subnet it is on and
> the ISC DHCP server offers it an address in the right subnet.

I wonder if this helps:


The result was that we had to remove the broadcast address entries on the 
router interfaces.
     .:.Sebastian Hagedorn - RZKR-R1 (Gebäude 52), Zimmer 18.:.
Zentrum für angewandte Informatik - Universitätsweiter Service RRZK
.:.Universität zu Köln / Cologne University - ✆ +49-221-478-5587.:.
                   .:.:.:.Skype: shagedorn.:.:.:.

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