[Samba] dynamic dns for Linux clients

[steve]

Version 4.0.6-GIT-9bfcb9f
openSUSE 12.3 client with 3.6.12
Hi
I've a problem with a Linux box joined to a domain which sometimes can't 
connect. Login, kinit fail. The DC doesn't recognise it. I've traced 
this to (almost certainly) DNS. When it's 192.168.1.21 it's fine. Maybe 
it was .21 when it first joined? The other Linux boxes work fine 
whatever DHCP gives them.

I've worked around it by giving it a static ip and setting the DHCP 
range from 22 up but it would be better if I could find out why it is 
the one box which is problematic. I've tried both Winbind and sssd on 
the client with the same results. Where would I start to debug this?

Cheers,
Steve