DHCP 4.2.3-P2 doesn't remove TXT and PTR records but only A

Eddie Lania e.lania at elton.nl
Thu Feb 16 07:24:00 UTC 2012


Thanks for the advice.

The clients in our network however are not allowed to do updates to the DNS themselves.
So, this is not a useful solution for me.



-----Oorspronkelijk bericht-----
Van: dhcp-users-bounces+e.lania=elton.nl at lists.isc.org [mailto:dhcp-users-bounces+e.lania=elton.nl at lists.isc.org] Namens Andris Kalnozols
Verzonden: donderdag 16 februari 2012 04:13
Aan: dhcp-users at lists.isc.org
Onderwerp: Re: DHCP 4.2.3-P2 doesn't remove TXT and PTR records but only A

> When dhcpd receives DHCPRELEASE for a client, it expires the lease for
> the client and removes only A record of the client but ignores PTR and
> TXT records.
> When a lease expires naturally without a DHCPRELEASE message, every
> resource record regarding the client is discarded.
> I think it is a bug.
> On Tue, Feb 14, 2012 at 4:29 PM, Eddie Lania <e.lania at elton.nl> wrote:
> > I was wrong, the records are only not removed on dhcprelease.
> > So, when a client sends a release then a PTR and TXT record are left behind.
> >
> > But if a lease expires then all records (PTR, TXT and A) are deleted.
> >
> >
> > crocket <crockabiscuit at gmail.com> wrote:
> > Subject: DHCP 4.2.3-P2 doesn't remove TXT and PTR records but
> >          only A records when leases are released or expired.
> >
> > Thus, I can't use dynamic DNS updates.
> > I don't want any resource record left behind after clients cut off leases.
> >
> > Will it be fixed in future releases? or can it be fixed by changing
> > the configuration?

In an effort to limit the perceived level of brokenness, I wish to
demonstrate that the 4.2.3-P2 DHCP server does work as intended when
using the following dynamic DNS related statements:

  ddns-update-style interim;
  allow client-updates;           # clients will update their own A records
  ddns-ttl 1200;                  # match that of the Microsoft DNS server
  option fqdn.rcode2      255;    # tell clients that the server understands
                                  # the fqdn option and will do the PTR update

  subnet netmask {
    zone 95.4.15.in-addr.arpa. {
      key      secret;

Doing an "ipconfig/release" on a Windows system signals the DHCP
server to do the expected action:

  Feb 15 16:05:22 lpans2 dhcpd: DHCPRELEASE of from
    00:30:6e:d7:31:09 (sp500-old) via eth0 (found)

  Feb 15 16:05:22 masterns named[1229]: update: info: client updating zone '95.4.15.in-addr.arpa/IN':
    deleting rrset at '' PTR

The client also deletes its A record.


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