I've searched around on Google and on AO, but the only proper thread relating to "setting up a domain" is a tut I found (here), but that is for Windows. As I have been employed to set up an ethernet network in an office, and I'm looking to convert all the computers there to Ubuntu Linux (over time), and I would like the network to be a domain rather than a workgroup (administering the domain from a Linux box).

Now, as far as I know, domains are more secure than workgroups, because you can do things like locking-down computers and stop users changing system settings (this only comes from my knowledge of a Windows domain). Now, what I would like to know is, how do I set up a domain from a Linux box (would Ubuntu be alright to set it up?), how I can set the permissions for config files on computers connected to the domain (all would be Ubuntu), how to set up a DNS server (I think you need to do this for your own domain), and all the other stuff like this. How would I be able to implement the server if all the computers were connected to a router? Would I need to connect the "domain" box to the router, and then have all the other computers connected to that one (via a hub or something)?

You can also attempt to convince me on why NOT to go for a domain and just use a simple workgroup! Remember, in an office, I would like the network to be reliable, secure, etc...Although I think that stuff's pretty obvious! Thanks in advance, and I hope I haven't confused you!