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Re: changing local domain name




On Sat, 31 Mar 2018 10:15:48 -0500
David Wright <deblis@xxxxxxxxxxxxxxxxx> wrote:

> On Sat 31 Mar 2018 at 12:35:08 (+0100), Joe wrote:

> 
> > If you lease a public domain name, there is no real
> > difficulty about using it also in a private network, just a matter
> > of making sure that external resources using the name can also be
> > found in local DNS or hosts files.  
> 
> If you could elaborate. Say I have leased example.org, currently at
> 93.184.216.34, and apart from what's out there on the Internet I have
> hosts foo.example.org at 192.168.1.2 and bar.example.org at
> 192.168.1.3 with a router at 192.168.1.1. What do I need to do? For
> simplicity, I use dhcp from the router which also has no DNS server.
> So /etc/hosts.

Practically nothing, I'd have thought. *If* you run a local DNS server
based on example.org, then you need to make the local machines aware
that Internet resources are not going to be found in the local network.
In this case, either that the DNS server has a manual entry or that all
your machines have entries in their /etc/hosts files for
www.example.org, on the sensible assumption that your web server is
externally hosted. If you don't have a DNS server keeping track of your
local machines, and in general, your workstations don't need to know
where each other are, then a few /etc/hosts entries should be all you
ever need. You only need the workstations to know where your servers
are, and you may not have any servers other than your router.

Nothing should need to know your public IP address: if you're hosting
any Internet-facing servers, the hosting company you're leasing
example.org from will deal with the public DNS. 

You will get a local DNS server when you acquire so many machines that
keeping all the hosts files in sync becomes a pain. I run BIND and
ISC-DHCP servers for the exercise, there are simpler DNS-DHCP systems.
I do need DNS, as I run a mail server, and I've found out the hard way
that the DNS forwarders in domestic routers aren't always up to the job.
But in the early days of doing that, the mail server looked after its
domains, I had only a caching nameserver in my router and the name of
the server computer, and its 'domain' were irrelevant. My Windows
workstations had a workgroup name, which Samba inherited when I began
using it, but it has no connection with any of my Internet domain names.

Again, a Linux workstation has no real use for a 'domain' name, but if
you make even trivial use of some application which is involved with
Internet domains, such as SMTP or DNS servers, then they may need to be
given a domain name. The Debian installer simply assumes that no harm
will come from the existence of a domain name if it's not needed, but
that many Debian installations do need it.

And no, I've never tried changing one, as I've always used one of my
email domains, which has not changed in twenty years. As a comparison,
if you need to change the domain name of a Windows server, you literally
need to reinstall it, as the name is used so widely in its registry and
its Active Directory. There is no method of changing it which is
supported by Microsoft.

-- 
Joe