mail confusion

[Derek Martin]

On Wed, Nov 02, 2005 at 12:29:14AM +1030, Tim wrote:
> >> I can see why they've done something *like* that, as there's some
> >> networking things that will insist on there being at least one dot in
> >> the name, but I would have done it differently.
> 
> Derek Martin:
> > Hmm... can you provide an example?
> 
> I can't remember off the top of my head, but one mail client, at least,
> flatly refused to allow me to specify localhost as the mail server.  You
> had to have at least one dot in the name before it'd let you continue on
> configuring the client.

Well, I think that's broken.  Reason: it's very possible to have an
internal mail system which does not connect to the Internet and
therefore does not need FQDNs.  Granted, that probably doesn't happen
much these days, but the option should exist.

> > And IMO you shouldn't... localhost is localhost -- it
> > isn't in a domain; that's the whole point.  The entire 127.0.0.0/8
> > network refers to your local machine.
> 
> See RFC 2606:  <http://www.faqs.org/rfcs/rfc2606.html>  But note
> "traditional" and the warning off (which doesn't explicitly preclude
> it's use, that way).

I'm not sure what you're trying to say here.  My reading of the RFC
agrees with what I wrote above.  If your point was something
different, then I guess I'll have to ask you to clarify...

> What is needed is a reserved domain name for local hosting of servers,

Why?  If the hosts are on a network which is connected to the
Internet, they'll have their own domain already.  If they're not, then
no domain is needed.  Or, if for the convenience of managing your
network, having domains makes sense, then you should register a domain
name anyway, even if you're not going to use it on the Internet.  That
way, if a time comes when you WANT to connect those systems to the
'Net, you don't need to reconfigure them all.

> "localhost" fits the description rather well, for picking a name for
> intuitive reasons.  It doesn't necessarily have to me the same machine,
> just something that's local.

I still don't see the need...
> 
> > I'm inclined to think that software which requires a domain is broken. 
> 
> There's any number of things that want a FQDN, mail servers being the
> first thing that springs to mind.

I can't speak for all mail server software, but I'm pretty sure
sendmail doesn't require an FQDN.  Which would make sense, since it
was written at a time when there were like 12 machines connected to
the Internet, and there were no FQDN's.  :)  And again, for those who
don't need to be connected to the Internet, this should not be a
requirement.  For those that do require it, I say they're broken. :)

The only server which SHOULD require a FQDN is the DNS server, for
(hopefully) obvious reasons.  :)  But even then, "myhost" can be a
top-level domain and have its own A record.  That's just not a very
useful way to manage DNS.  Still, possible.

-- 
Derek D. Martin
http://www.pizzashack.org/
GPG Key ID: 0x81CFE75D

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