In the DHCP Network settings, there are separate options for 'DNS Domain' and then simply 'Domain'.

After some basic testing, I see that these fields are essentially the same and you can't set them as different values.

So my question really is why the two options? Why not just one? Is this some legacy issue?

Bottom line is that this setting(s) sets the DNS suffix as you can manually set in Windows.

yesss, just a bug in WinBox. appeared after 3.27 (not sure about 3.28-29). and it's absent in terminal =)

Thanks Chupaka!