[Samba] logon requests on the BDC

[Thierry Lacoste]

From the Samba Howto:

 The BDC is biased to answer logon requests in preference to the PDC. On a
 network segment that has a BDC and a PDC, the BDC will most likely service
 network logon requests.

While this appear to be the case on my test network all my tests show that
this is not true on my production network.
AFAICS both networks have the same software configurations and on each
network the BDC runs on the same hardware as the PDC.

Are there special things to do to make the BDC bias work?
How can I troubleshoot the reason why it does not work?

Regards,
Thierry.