Dynamic Update ISC DHCP Stale Records

briandesu brwilson at adelphia.net
Wed Feb 18 23:35:43 UTC 2004


Chris Cox <chris_cox at stercomm.com> wrote in message news:<c10bl0$2987$1 at sf1.isc.org>...
> briandesu wrote:
> > Ladies & Gents,
> > 
> > I have set up a BIND 9.2.1 server and ISC DHCP 3.0 server to perform
> > dynamic updates for Active Directory.  However, I am having a problem
> > with stale records.
> > 
> > Is it possible to configure the ISC DHCP server to remove the stale
> > records in the same fashion that a M$ dhcp server removes stale A and
> > PTR records from a Winbloze dns server?  If yes, what are the required
> > parameters in the dhcpd.conf file?
> 
> What's the problem with an A record??  If something else needs
> to consume the address/name, ISC dhcp will do the right thing and
> clean out the old A/PTR records (unlike M$).  What's the harm
> in keeping the entry??  Even if the lease expires, the client
> will likely request the last address it had.. so unless you
> have a fully loaded dhcp pool... your client hosts will just get
> back the same address anyway.


> I've never had a problem with the extra entries.  If it really
> bugs you (and I would hope that it wouldn't), you could write
> a quick script to determine expired dhcp entries and fire off
> dynamic update requests using nsupdate from the dhcp server
> to remove the "stale" entries.... but I personally think it's
> not necessary to do this (this method could be very accident
> prone).

I thought about writing a script as you have suggested.  However, like
you said, this might yield undesirable results.  Given that Active
Directory clutters the zone considerably, my main motivation is
maintaining a cleaner zone file.

I would like to determine if such a cleansing mechanism is built into
the ISC DHCP server, and if so, how to activate it.  I did not find
anything in the man pages indicating so.

Thank Again,

Brian


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