Re: domain names, was: hostname
Jeremy Nicoll wrote:
> Thanks to everyone who replied, not just Dan...
>
> So...
>
> On Mon, 19 Feb 2018, at 13:30, Dan Purgert wrote:
>> Jeremy Nicoll wrote:
>
>> > What, on a home LAN, is that used for?
>>
>> In general terms, supplying domain information at setup time adds a
>> "helper" record to /etc/resolv.conf (or whatever RH, Windows, etc.
>> uses). Note that if you use DHCP, this step is usually skipped, as the
>> DHCP server provides the information.
>
> On a Win8.1 system, ipconfig /all does show me a hostname (the same
> value as %COMPUTERNAME%) which happens to be a combination of the
> machine's manufacturer name, and model
>
> There's no domain value at all, though DHCP is in use... but I suppose I
> configured the DHCP server (in the router/switch) and maybe left fields
> blank there...
Yep, it's because your DHCP server does not have anything set. I
should've said something more like "if you're setting a host to use
DHCP, the setup assumption is that the DHCP server will provide it".
Of course, it is not a requirement that the DHCP server provide this
information.
>
>
>> In short, the "helper" record appends the domain name to a hostname, so
>> you don't have to type out a FQDN when you're trying to get to a remote
>> host.
>
> Do you mean when someone outside the LAN is trying to connect to my
> machine? I'd assume that makes sense only on a corporate / company
> LAN with a static IP gateway address and that address would be defined
> in DNS matching the company's domain name... and - if that's right - I
> can see that telling each pc on the LAN that it's part of the company's
> domain makes sense...
No, I mean for your own local network. It's so that when you're on the
LAN, you can just connect to a host by its name. It doesn't help at all
off the local network.
Say your "domain name" is cybertron.net and you have three hosts -
OptimusPrime, Bumblebee, and Ironhide.
Normally, if you wanted to ping one of them, you'd have a command along
the lines of "ping Ironhide.cybertron.net" ... kind of a lot of typing,
so you can add the "helpers" which lets you simply use a hostname in
your commands -- "ping Ironhide".
>
>
> Other than that, opinion seems divided on whether for a home LAN it
> makes more sense to leave domain name unset, or to provide a value
> (picked carefully, perhaps ending ".test" or ".invalid"). In some ways
> I like the idea of providing a planned/known name, if only because I'd
> recognise it for what it is if I saw it in error messages, logs etc in
> future.
If you're going to set up a local domain, double-check the RFCs for
reserved / allowed to use without registration TLDs -- and make sure
you're checking CURRENT docs (stff like "*local" used to be allowed, but
now it's set for mDNS / bonjour / avahi).
Or pay $15 for a year (ish) and get yourself your own registered domain,
and don't worry about it getting changed somewhere down the line.
>
> I almost wonder if, to avoid any potential name conflict, one would be
> sensible to register a domain, and then NOT have it point at one's own
> home LAN - because unless a dynamic DNS service is used, how could
> one keep that uptodate (my cable internet ISP does change my WAN
> ip address occasionally) - and use its name on the home system. But
> then again that might have unintended consequences.
>
That's what I do (except I do also pay for ddns, because I use my domain
name for simple things with friends / family). The real killer is paying
for TLS certs, though perhaps this year I'll move everything to Let's
Encrypt.
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