Noob questions about domainname, hostname

[dhave]

I've been managing to use Slackware and Gentoo for about three years now, but I still have some big gaps in my knowledge. For example, I've never been really clear about some basic concepts like "hostname" and "domainname" when it comes to a standalone computer or a small home network.

Somehow when I did my current Gentoo installation (my third), I neglected to define a domainname. My questions:

(1) Can I now go back and define a domainname? If so, what's the best way to do that?

(2) Is defining a domainname at this point going to cause problems? My system's humming along fine with just a hostname, and I'm not sure I should rock the boat. Should I just let well enough alone?

(3) My machine is one of three machines on a small home network. The other two machines are WinXP systems. Do I need to have a single domainname for all three? The Windows network, via which I print and sometimes grab a file from another machine on the LAN, is called MSHOME. Should I use that as my Linux domainname? Or can I choose any old thing?

Thanks a lot for your help with these noob questions.
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[laidback_01]

(1) Can I now go back and define a domainname? If so, what's the best way to do that?

Yes, your domain name is specified in /etc/hosts as
123.123.123.132 host host.domain.name
You could also run a name server to allow others to realize this. If you want windows machines to know you, you'll need to have a lmhosts file available for samba to use, or edit their hosts files.

(2) Is defining a domainname at this point going to cause problems? My system's humming along fine with just a hostname, and I'm not sure I should rock the boat. Should I just let well enough alone?

No, you can change it at will... nothing bad comes of it.

(3) My machine is one of three machines on a small home network. The other two machines are WinXP systems. Do I need to have a single domainname for all three? The Windows network, via which I print and sometimes grab a file from another machine on the LAN, is called MSHOME. Should I use that as my Linux domainname? Or can I choose any old thing?

You can use any domain name you like. it's not the same as the SMB workgroup names, though they can be used...
I'm not perfect on this myslef. Anyway, you'll set the name MSHOME in /etc/samba/smb.conf for the item "workgroup"
you can include this workgroup in your /etc/hosts, but it doesn't seem to matter. you can also have a different or similar (either way is fine) name in /etc/hosts and expect it to work fine. You'll also see some stuff in samba for lmhosts files, which you have to create - they are simlar but not the same as the hosts file. after you do that, make sure that you let samba know to handle the lmhosts file, and to tell the windows machines to get the lmhosts file from your linux box.

If you are not going to make the linux box act as a fileserver in charge of the network, then ignore the above and just put MSHOME in the /etc/samba/smb.conf file as the workgroup name so that the linux machine can see the windows machines and vice-versa.

[dhave]

Thank you for the good explanations and instructionas, laidback_01.
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