Various "domains"

1)
NIS domin is set in file /etc/defaultdomain (?) in Ubuntu and not as in RH in /etc/sysconfig/networking

The following commands are related to the NIS domain (but not the other types - confusing and important tho know). I think neither of these commands affect the setup and only affect the current session.

domainname - set or display name of current domain
nisdomainname - set or display name of current NIS(YP) domain
ypdomainname - set or display name of current NIS(YP) domain
2)
The IP domain (i.e. network DNS domain) is set in the file /etc/resolv.conf

use the commands hostname -d or dnsdomain to show/set

3)
Windows domain is set in /etc/samba/smb.conf. When using samba filebrowsers on a shared you need special access to, which "domain" to use is selected to the default WORKGROUP name. I havn't figured out how (if possible) to change this.