DHCP clients losing address / backdated lease date

Nicolas C. dhcp at nryc.fr
Thu Nov 29 11:22:01 UTC 2012

Le 29/11/2012 09:29, Alpar Torok a écrit :
> Nicolas,
> I observed similar behavior. For reasons I don't want to go intohere, we
> were doing an instant time synchronization.
> This caused the dhcp client to send a  DISCOVER rather than  a REQUEST,
> but included the obtained IP address.
> The server pinged the address before OFFERing it, but got a reply from
> the client, that haven't released it yet, and
> so it was handing out a new IP address.  To my knowledge, both the
> behavior of the client and the serve are correct.
> Do to the time sync, the state of the dhcp client jumped trough the
> renewal phase.I didn't find anything specific
> in the standard around this, so I guess it's implementation specific.

Hello Alpar,

I'm very interested by your response because I also have clients doing 
DISCOVER instead of REQUEST. This happens every 90min regardless of the 
lease time and cause the exact same problem you describe.

Can you elaborate a little more the "instant time synchronization"? Does 
this means the clients have problem with their clock?

We use Kerberos for our servers and workstations so everything is 
supposed to be sync by NTP otherwise authentication doesn't work.


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