DDNS client: Multiple zone entries

nsvora nirav.s.vora at gmail.com
Fri Oct 27 16:35:16 UTC 2006

Merton Campbell Crockett wrote:
> On 25 Oct 2006, at 14:46 , nsvora wrote:
> > Hi All,
> >
> > While testing the DDNS server configuration with proprietory client, I
> > noticed a strange thing. I need your help to understand this.
> One way of minimizing the occurrence of multiple host name records is
> to configure DHCP to use "ddns-update-style interim;".  With this
> change, DHCP collects a little more information about the system
> requesting an IP address.  In addition, it adds some additional TXT
> records to the zone file for tracking purposes.  When the lease
> expires it removes DNS entries from both the forward and reverse zone
> files.
> The interim style also ensures that the DNS entries are removed on a
> DHCP release.  If you remember to release the DHCP address before
> changing the system's host name.  You will eliminate the problem.
> However, if you forget to release the IP address, you will only have
> "multiple" entries for the unexpired time of the lease.
> The interim style does make an attempt to remove the old DNS data but
> it isn't totally reliable.
> Among the additional pieces of information maintained in dhcpd.leases
> is the MAC address.  If you change the NIC in the system, you will
> need to know how to use nsupdate to clean up the zone files. :)
> Merton Campbell Crockett

Hi Merton,
Thanks for detailed explaination. I have the proprietory implementation
of both DHCP and DDNS clients which i am testing with LINUX servers. I
already have interim style update
set in the dhcp configuration. But since I have my own implementation
of clients, this wont help. I would probably need to put the fix in the

About releasing the lease, is it good idea to release lease even if
lease time has not expired.

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