Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!ucsd!helios.ee.lbl.gov!ncis.tis.llnl.gov!mcb
From: mcb@ncis.tis.llnl.gov (Michael C. Berch)
Newsgroups: news.sysadmin
Subject: Re: Re: Stuck with .UUCP forever?
Summary: Internet forwarding
Message-ID: <198@ncis.tis.llnl.gov>
Date: 21 May 89 05:38:25 GMT
References: <1728@fig.bbn.com> <3790007@eecs.nwu.edu> <320@xdos.UUCP>
Organization: Lawrence Livermore National Laboratory, Livermore CA
Lines: 46

In article <320@xdos.UUCP> doug@xdos.UUCP (Doug Merritt) writes:
> [...]
> Ok. But I'm still missing one central point: why can't I simply register
> my machine as "xdos.com", and automatically have Internet forwarders
> know who I am? Why is it necessary to make a personal arrangement with
> some such machine? I don't see why it can't be as easy as it is with
> registering uucp map connections. Is it just due to historical problems
> that grew out of the old arpanet, that no one has gotten around to
> changing? Or is there some inherent reason for it?

The latter.  There's no such thing as "Internet forwarders" in
general; what matters is *your* site's Internet forwarder(s), which
means the machine or machines that are named in MX records in the
name server for your domain.  

Here's how it works: the servers for the top level domain COM are the
root servers of the Domain Name System (DNS).  They contain a name
server (NS) record that will show the name of the name server for your
domain.  Let's say that machine is NS.FOO.GOV.  A resolver will then
contact NS.FOO.GOV looking for an MX (mail exchanger) record for the
particular machine in your domain (or a wild card that matches the
whole domain).  The MX record or records (there may be several) 
will point at hosts that are forwarders for your machine.  

This latter relationship is something *you* must arrange with the
forwarding site, because all that site's machine is going to get when it's
forwarding for you are messages addressed to "doug@xdos.com" suddenly
showing up in its incoming SMTP connections.  It's gotta know what to do
with those pieces of mail, like (for example) sending them direct by
UUCP or over a private line, or whatever.  So the forwarding site has
to specially configure its mailer to handle the messages that it is
forwarding from the Internet.  There's no way to trivially automate this; 
it requires that the forwarder has some existing method of sending mail
to you (or sets one up at your request), and configures its mailer to
special-case your site.

The example you give comparing this to UUCP map registration is a
reasonable analogy, but remember that before you registered the map entry 
you had to personally set up all the UUCP connections that are mentioned
in it.  The same is true for domain registration; you have to set up
the forwarding relationship yourself, but once you do so, registering the 
domain and getting it into the Domain Name System is simple & cheap.

--
Michael C. Berch  
mcb@tis.llnl.gov / uunet!tis.llnl.gov!mcb