XP clients sometimes ignore DHCPOFFERs

John Wobus jw354 at cornell.edu
Mon Mar 20 14:58:27 UTC 2006

On Mar 16, 2006, at 11:46 AM, Brent L. Bates wrote:

>      This may not help, but while trying to figure out why dhcpd wasn't
> working on one of our systems, I noticed similar behavior.  The dhcpd 
> server
> would see the DISCOVER's and send out OFFER's, but the PC would never 
> see
> them.
>      For us, the problem was that the PC was expecting the offer to be
> broadcast via and the server was doing 
> server_subnet.255.  I
> was using tcpdump to check what the network traffic was doing.  I gave 
> up
> trying to get it to work on that system (SGI IRIX 6.5.22, `raw send' 
> doesn't
> compile clean) and moved to another platform (SL 3.0.5).
>      I hope that helps some.

This is a problem I've seen.  It happened when the PC had
an address and mask configured at the time that the OFFER
was sent, and was masking it out.  Some PCs at some
Windows levels would manage to configure the 169 address
before the DHCP sequence had completed and would often end
up in this state. Most PCs did not have the problem.  When I got
my hands on an example PC, I found the quickest way to recover
was to unplug and plug in the PC from/to the net.  Renew did

To prevent the problem, we switched our router broadcast
addresses from SPECIFIC.SUBNET'S.ADDRESS.255 to  I assume Microsoft's server uses the

John Wobus
Cornell CIT

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