DDNS handling of "dumb" DHCP clients
dhcp_email at congenio.de
Thu Aug 9 16:28:23 UTC 2012
> Right, but you can have the DHCP server assign a static address - so from the
> device's POV it's just a regular DHCP lease (while not really a lease for
> dhcpd). When using the DNS name in the corresponding host declaration all you
> need is change the DNS record, restart dhcpd and on next request the deivce
> will get the new IP. Nothing the client needs to know.
You noticed the word "static" there? The whole point of DHCP is to
assign dynamic addresses. With your approach, I do not even need DDNS at
all, as the devices DNS entries were static as well.
As I already wrote, we can and do use "fixed-address" now - but these
addresses are derived from a database and have to be maintained for
printers that are in a shared network in which pools have to be altered
because of NOC contraints. I am not talking about three or four of these
types here. Such modifications are done almost daily here.
For clarity, what I want, is:
Clients which are given dynamic addresses from a pool and for which the
DHCP server does the DDNS updates WITHOUT the need for the clients to
send the FQDN option (because they are "dumb").
The DHCP server can be provided a "host" configuration entry which
specifies the client's DNS name (no matter if "ddns-hostname",
"hostname" or by using "use-host-decl-names" is being used), however
using "fixed-address" is not an option, for the named reasons.
And exactly that is what the documentation says ISC DHCP can do - alas,
specifically only for deprecated "ad-hoc" DDNS style.
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