dhcpack instead dhcpnak

[Steven Carr]

If the client already has the lease and it is requesting a renew then
they DHCP server will acknowledge the renew request and the client
will continue to use the address indefinitely, as far as the DHCP
server is concerned the leases file says the client has a lease for
that IP address and will skip looking at the config part. Only if the
lease has expired and the client performs a DHCPDISCOVER will the DHCP
server look at the configuration and give the client the different
address.

You can't really prevent this other than don't change the IP address
to another address in the same subnet. The workaround is that you will
need to force the client to release it's current IP address then
request a new address.



On 28 May 2013 16:11, benek <zbyszek.r at retsat1.com.pl> wrote:
> Hi,
> I noticed a strange behavior of the dhcp server (the dhcp3-server 3.1.1-6 +
> lenny4 on debian). All users have so defined addresses:
> "... the ethernet hardware aa:bb:cc:dd:ee:ff; fixed-address 10.20.30.40;..."
> When I changing the ip address for a given mac in dhcpd.conf sometimes the
> server responds with DHCPACK to the DHCPREQUEST with a non-existent ip
> address and the user receives a non-existent settings in dhcpd.conf.
> Normally should respond DHCPNAK and force of a new lease process.
> What could be causing this behavior and how I can prevent it.
>
> Regards
>
> benek
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