DHCP Failover DDNS leases file issue or bug?

[Colin Simpson]

Hi

I have been playing with using failover DHCP. We also use dynamic DNS
updating. I'm using RHEL 6 with dhcp-4.1.1-12.P1.el6 which I'd guess is 
just 4.1.1

The scenario I have been testing is Primary server down and secondary
up. 

In this situation the secondary adds the machine to it's leases file and
all is fine:

lease 10.10.20.80 {
  starts 6 2011/02/12 23:19:43;
  ends 6 2011/02/12 23:49:43;
  tstp 4 2011/02/17 23:34:43;
  tsfp 6 2011/02/12 22:27:56;
  cltt 6 2011/02/12 23:19:43;
  binding state active;
  next binding state expired;
  hardware ethernet 00:18:8b:ce:1f:35;
  set ddns-rev-name = "80.20.10.10.in-addr.arpa";
  set ddns-txt = "005a7b5d8da950c0632c21e7b21d995b4c";
  set ddns-fwd-name = "testC.iongeo.com";
  client-hostname "testC";
}


However on bringing the primary back up it add only a small subset of
these items to its leases file:

lease 10.10.20.80 {
  starts 6 2011/02/12 23:19:43;
  ends 6 2011/02/12 23:49:43;
  tstp 6 2011/02/12 22:27:56;
  tsfp 4 2011/02/17 23:34:43;
  atsfp 4 2011/02/17 23:34:43;
  binding state active;
  next binding state expired;
  hardware ethernet 00:18:8b:ce:1f:35;
}

What will now happen to DNS when the lease expires?

Does the Secondary handle this and remove this entry from DNS properly?
Or will the primary be responsible and do nothing with DNS?

And what if the secondary is now goes down, we'll presumably just end up
with lots of stale DNS entries that won't get removed ever? Or will they
remove when/if the secondary comes back and sees it has DNS entries it
needs to now expire (or isn't it that clever).

Is this a bug? Shouldn't it send all the fields across when they resync?

It looks like the leases file does get updated on both for dns items if
both are up when a renew comes from the client. Strange.

Any thoughts?

Thanks

Colin




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