DHCP DISCOVERs but no OFFERs - update

Frank Bulk frnkblk at iname.com
Fri Mar 16 20:19:47 UTC 2007

I did a bit more digging around my logs and saw that there was a ping ahead
failure in correlation to each DISCOVER.  I had accidentally wiped out my
leases for that subnet (3rd-party vendor GUI) and the ping ahead was finding

Why doesn't the DHCP server mark that IP address as abandoned and then go on
to the next free one and run another ping ahead, rather than wait for the
next DHCP DISCOVER?  Depending on the DHCP client's behavior and the number
missing leases (a lot, in my case), it could take minutes to hours before
the DHCP client receives a DHCP offer.


-----Original Message-----
From: dhcp-users-bounce at isc.org [mailto:dhcp-users-bounce at isc.org] On Behalf
Of Frank Bulk
Sent: Wednesday, March 14, 2007 9:12 PM
To: dhcp-users at isc.org
Subject: DHCP DISCOVERs but no OFFERs

We had a strange problem pop up yesterday that's pretty intermittent.  We
have approximately 1400 cable modems in production and we're getting a few
per day that don't immediately boot up.  

What we discovered looking at the syslog and packet traces is that the cable
modem is issuing DHCP DISCOVERs but the dhcp server is not sending out an
offer.  Then after 15 to 45 minutes, the DHCP server responds with an OFFER
and so on and life is good.

Does anyone have an idea why the DHCP server would act like that, and are
there any ways I can better debug this problem to understand *what* the
dhcpd process is doing that it might be ignoring the DISCOVERs?

We're running V3.0.4 on a Linux 2.4.34-pre4 kernel.

Kind regards,


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