Fixed address inside dynamic range

perl-list perl-list at
Tue Mar 6 14:32:54 UTC 2012

Not that this is exactly on-topic for this thread, but I would like to make sure I am correctly understanding... 

It seems that in DHCPv6 that fixed-address6 DOES remove the IP from the pool. man dhcpd.conf: 

" Any IPv6 addresses given to hosts with fixed-address6 are excluded from the range6, as are IPv6 addresses on the server itself. " 

That seems pretty clear, but given that this is NOT the case in DHCPv4, I just wanted to clarify. 

----- Original Message -----

> From: "Simon Hobson" <dhcp1 at>
> To: "Users of ISC DHCP" <dhcp-users at>
> Sent: Tuesday, March 6, 2012 9:25:22 AM
> Subject: Re: Fixed address inside dynamic range

> Nuno Marques wrote:

> >Isn't there any option so the dhcp server doesn't give a dynamic
> >client one already used fixed address?

> No

> >It would be a real pain to reconfigure all my networks (which have
> >lots of hosts inside dynamic range)

> You reap the reward for an unplanned (not well managed ?) network.

> >Any thoughts?

> You may want to consider reserved leases. These act like normal
> leases, but cannot be re-allocated to another client.
> So you get the benefit of having a "fixed" address for a client, but
> also the advantages of following the normal lease lifecycle (so DNS
> updates work for example).

> --
> Simon Hobson

> Visit for books by acclaimed
> author Gladys Hobson. Novels - poetry - short stories - ideal as
> Christmas stocking fillers. Some available as e-books.
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