"update-optimization false" and ddns-fwd-name / client-hostname
Nicolas C.
dhcp at nryc.fr
Sat Jan 26 10:27:30 UTC 2013
Hello,
I'm using two dhcp servers in failover mode (v.4.2.2, Debian Wheezy),
the primary failover hosts a bind server.
We have DDNS in place and, to make sure the dynamic zones are
up-to-date, we have the "update-optimization false" option on both servers.
For some workstations, the DHCP keeps renewing the leases but does not
perform the DNS update. We know this happens on some workstations always
powered on (easy to detect) but it may also happens for regular clients
connected during office hours.
There are two workaround to this problem :
- on the client : force a DHCPRELEASE + DHCPDISCOVER
- on the server : put a temporary "deny booting" to force the client
to renew its lease on the other server (it forces the DNS update).
I made a tcpdump capture and did not find anything unusual, restarting
the DHCP server has no effect.
After reviewing the lease file, I found that the "client-hostname"
doesn't match the "ddns-fwd-name".
Is this the cause of the DDNS failure? If yes, is there a reason why
ddns-fwd-name/client-hostname are not the same?
lease 172.20.11.145 {
[...]
uid "\001\000\014)\371_\335";
set ddns-rev-name = "145.11.20.172.in-addr.arpa.";
set ddns-txt = "31bf1c64c8bdb1545e31ab674317707873";
set ddns-fwd-name = "windows-dedevh1.domain.ltd";
client-hostname "WIN-SQ6ADOG23I8";
}
Regards,
Nicolas
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