DDNS Updates

[smallpond]

Kleinfeld, Ralf wrote:
> Hi,
> I am trying to find out more about how exactly ddns workds from the dhcp
> server
> point of view.
>
> If a clients receives an ip adress and the servers is configured to do the
> updates,
> what exactly happens there.
>
> I went through "The DHCP Handbook", but found no deep technical description
> of what happens.
>
> As far as I see in the log, it's looking for an existing A Record for the
> clients name.
> Furthermore it looks for a TXT records.
>
> What is exactly the meaning of the string value of the TXT records, which is
> created
> along with an A record?
>
>
> Furthermore, I have noticed that the dhcp server is NOT updating an A
> record, if the
> appropriate TXT record is missing. Is there a way to "force" the dhcp server
> to touch
> the record?
>
> What event forces the dhcp server to update DNS? Is it only happening on
> behalf of
> a DISCOVER-OFFER-REQUEST-ACK or also on a renew within the leasetime?
>
> Regards,
> Ralf


When using interim update style, the DHCP server will only update a DNS
record if it doesn't exist, or has a TXT record which matches the one
in dhcpd.leases.  This allows multiple DHCP servers to coexist without
stepping on each other's records, and allows an admin to use nsupdate
to set a record which won't be touched by DHCP.

If you have modified the record with nsupdate, and want DHCP to manage
it, you will need to delete the record first, and then get the client
to make a new request. (rebooting a PC works).

-- s