DDNS updates

Kleinfeld, Ralf Ralf.Kleinfeld at mgi.de
Tue Aug 1 11:48:20 UTC 2006

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


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