samba - Aug 2014 - Response from an incorrect interface on Samba PDC 3.6.6-6+deb7u4 Debian Lenny

Hi!

First at all here is a infraestructure brief description:

Samba version 3.6.6-6+deb7u4 on debian lenny

+-------------+
 |   SAMBA    |eth_a----------LAN_A
 |    PDC     |
+-------------+eth_b----------LAN_B
      eth_c
       |
       |
       |
+--------------+
 |             |
 | GATEWAY     |--------------LAN_C
 |             |
+--------------+

Now the issue:

    When we run a ping test from "LAN_C", samba server response from
the
correct interface throw the gateway (in this example case eth_c), and
the same occurs when we try to access to the shared resources, and
that's ok. But when we try join to domain, the samba server response the
broadcast DNS query from any other interface like eth_a with the ip
source address corresponding to LAN_A, and if shutdown the interface
eth_a from eth_b and so on.
    Everything works ok if we try to join to domain from LAN_A and LAN_B
where the samba server are directly connected.

Regards and thanks!
Ignacio