[Blind-sysadmins] setting Primary Dns Suffix via samba

There is something wrong with my samba domain. The main symptom is that after a DHCP lease expires, I get an invalid DNS suffix search list. It should be "math.wisc.edu" but it gets set to another department like "junk.wisc.edu". If I renew the lease, 'ipconfig /renew', it's right. However, the Primary Dns Suffix is always empty. I'm not finding anything on samba.org on how to set that. I know it can be hard coded in via the Windows control panel. But I don't want to have to fix that on all 200 computers that we have in our department. Most of them are booted into linux most of the time anyway. So how to I configure samba to set the Primary Dns Suffix for Windows and how do I stop it from changing the DNS suffix search list?