dhcp server giving out new IPs on reboot

[Gregory Machin]

Thanks for the explanation it is much appreciated. Yes it is a tad old
lol .. it will be switched over the a new server soon :-) .

On Thu, Mar 1, 2012 at 10:52 AM, Simon Hobson <dhcp1 at thehobsons.co.uk> wrote:
> Gregory Machin wrote:
>
>> I have a legacy dhcpd 3.0.1 server.
>
>
> That's more than a tad old !
>
>
>> Users complain that when they reboot machines they get a new ip each time
>> .. Some of these machines are rebooted 5 times a day as part of testing.
>> This seems to happen once the lease range if full or almost full , is this
>> normal behavior ? I see no errors in the log files.
>
>
> it may be. If your range is getting quite full, then it's possible you are
> hitting a situation where you reboot a load of machines, there aren't any
> free leases, and so old ones are re-allocated. The machine that had the
> lease 1/2 hour ago now cannot have it's old address so it gets one that had
> been used for another machine. And so it goes on.
>
> It will be especially bad if you are multibooting with different client
> IDs*, as may be the case when machines have a net boot facility turned on.
> In this case, the netboot client will need an address and it won't match an
> existing one - because it's long enough since the machine last booted that
> it's lease is long since expired and reused. So it definitely reuses another
> old lease and so triggers the round of A gets B's old lease, B gets C's old
> lease, C gets ....
>
> You really need to have enough spare leases to satisfy all the clients at
> once - and that may mean 2 or even 3 addresses per physical machine is you
> are using PXE (or even have it turned on on the clients).
>
>
> * If client supplies a client ID then that is used as the primary key. If no
> client ID is supplied, then the fallback is to use the MAC address. If a
> client boots with different client IDs, or boots with and without one, then
> it is classed as different clients by the server.
>
> --
> Simon Hobson
>
> Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
> author Gladys Hobson. Novels - poetry - short stories - ideal as
> Christmas stocking fillers. Some available as e-books.
> _______________________________________________
> dhcp-users mailing list
> dhcp-users at lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users