domain login across subnet - how?

[mark at hoist.nlcomm.com]

Hello there!

I have three subnets, each connected to a "backbone" via routers.  I
have a Linux system, running Samba as an NT domain controller, on the
backbone.

However, the workstations on the subnets cannot login to the domain;
the domain logins work only on the same subnet as the Samba machine.

Could a kind soul please give me a few quick email replies on how to
set this up?  I have been administrating Samba for about two years so
I know how it works quite well; it is just the crossing of subnets
that has me puzzled.

I definitely want to avoid LMHOSTS if at all possible.

Thanks!
Mark