dhcpd.conf for dynamic dns

Glenn Satchell Glenn.Satchell at uniq.com.au
Tue Mar 20 13:09:59 UTC 2007

Well you could hack the source code...

I assume you want to do this because you have many records to clean up.
Perhaps you could write a script that parsed the log file looking for
the error message, collect the hostnames and use nsupdate to delete the
records it found.


>Subject: RE: dhcpd.conf for dynamic dns
>Date: Tue, 20 Mar 2007 16:49:04 +0800
>From: "Chow Chi Ho \(FP&HO\)" <chchow at cabletv.com.hk>
>To: <dhcp-users at isc.org>
>any way to force the updating even the records are exist  on dns ?
>-----Original Message-----
>From: dhcp-users-bounce at isc.org [mailto:dhcp-users-bounce at isc.org]On Behalf Of 
Simon Hobson
>Sent: Tuesday, March 20, 2007 4:03 PM
>To: dhcp-users at isc.org
>Subject: RE: dhcpd.conf for dynamic dns
>S Kalyanasundaram wrote:
>>Oh cool now the dhcp talks to dns!.  I think while updating the dns 
>>there will be some TXT data written in lease file as well. Better 
>>delete the lease file and touch it again and try it. ( I hope you 
>>are not in the productive environment).
>NO, don't do that.
>>"Chow Chi Ho
>>(FP&HO)" <chchow at cabletv.com.hk> wrote:
>>>  There is a response from dhcp server to dns server after I 
>>>removing  "option
>>>  fqdn.server-update on;"
>>>  and add "ddns-hostname = concat ( suffix .........)); "  to the pool.
>>  > But I got another problem  "  if 00e06f584da4.example.com IN A 
>>rrset doesn't
>>>  exist add 00e06f584da4.example.com 43200 IN A RRset already
>>>  exists. "  , log from dhcp server.
>>>  and the dns server " 'rrset does not exist' prerequisite not satisfied
>>  > (YXRRSET)  "
>That should be pretty self explanatory - it means that the record 
>"00e06f584da4.example.com A" already exists.
>This server will NOT overwrite an existing record that it did not put 
>there itself - this is to stop someone naming their machine the same 
>as one of your servers and hijacking connections to it !
>Delete the record and try again, the dhcp server will attempt to 
>update again next time the client renews. If that is successful then 
>you will see the A record and an additional TXT record which is a key 
>put there so that the DHCP server knows that it created the record 
>and so it can safely delete or replace it.

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