Removing incorrect ddns info from lease

Frank Price fprice at
Tue Nov 17 16:47:21 UTC 2015

Hi dhcp-users,

Internet Systems Consortium DHCP Server 4.2.5
IND 9.9.4-RedHat-9.9.4-18.el7_1.1 (Extended Support Version)
dhcpd failover

I'm struggling with some of my clients occasionally losing their ddns
entries, or not having them updated.  In an effort to fix things up, I want
to remove DHCID info from the lease.  The dhcpd.conf man page tells me
"data can be removed from the lease through operator intervention," but is
light on details:

In addition to these differences, the server also does not update very
> aggressively.  Because each DNS update involves a round trip  to the DNS
> server, there is a cost associated with doing updates even if they do not
> actually modify the DNS database.  So the DHCP server tracks whether or not
> it has updated the record in the past (this information is stored on the
> lease) and does not  attempt  to update records that it thinks it has
> already updated.

> This can lead to cases where the DHCP server adds a record, and then the
> record is deleted through some other mechanism, but the server never again
> updates the DNS because it thinks the data is already there.  In this case
> the data can be removed from the  lease  through operator intervention, and
> once this has been done, the DNS will be updated the next time the client
> renews.

Here's one of the leases in question:

lease {
  starts 1 2015/11/16 21:31:22;
  ends 2 2015/11/17 21:31:22;
  tstp 3 2015/11/18 09:31:22;
  tsfp 3 2015/11/18 09:31:22;
  atsfp 3 2015/11/18 09:31:22;
  cltt 1 2015/11/16 21:31:22;
  binding state active;
  next binding state expired;
  hardware ethernet f8:bc:12:3f:69:90;
  uid "\001\370\274\022?i\220";
  set ddns-rev-name = "";
  set ddns-txt = "31cce6d6ea09aa5603b3d319af3022007a";
  set ddns-fwd-name = "";
  client-hostname "yocto023";

Intuition says it's one of the ddns-* options, but my intuition often

1.  What information should I remove from the lease?
2.  Is there a recommended way to do this that doesn't involve manually
editing the leases file?

Thanks as always for any help you can provide,

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