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Path: utzoo!watmath!clyde!burl!ulysses!ucbvax!nike!styx!fair
From: fair@styx.UUCP (Erik E. Fair)
Newsgroups: net.mail
Subject: Re: colons, atsigns, & domains in uucp path keys
Message-ID: <20592@styx.UUCP>
Date: Thu, 24-Apr-86 21:19:07 EST
Article-I.D.: styx.20592
Posted: Thu Apr 24 21:19:07 1986
Date-Received: Sat, 26-Apr-86 05:38:25 EST
References: <404@geowhiz.UUCP> <13328@ucbvax.BERKELEY.EDU> <899@decuac.UUCP>
Organization: Lawrence Livermore Laboratory, Livermore, CA
Lines: 79

In article <899@decuac.UUCP> avolio@decuac.UUCP writes:
>
>gadzooks.Berkeley.EDU works from UUCP but *not* from the ARPA
>Internet???  Shouldn't the ARPA address be similar to the UUCP as in
>
>	joeblow@gadzooks.Berkeley.EDU  ?
>
>What's with the %?  (I know why it is there and what it means. But why
>aren't things changing for the better?)

OK, time for a quick course in ``Reality, Internet Style.''

In bang land, when you use ucbvax!foo.berkeley.edu!luser, who's doing
the interpretation of that funny host name with the dots? Why, ucbvax
of course.

Now, in internet land, when you use luser@foo.berkeley.edu, who does
the interpretation of that dotted name? The host you're on. Ooops...

There are two ways to deal with a host name on the internet:

	1. look it up in your copy of hosts.txt (maintained centrally
		by the Network Information Center (NIC), which you FTP
		from SRI-NIC.ARPA when it changes)
	
	2. ask your friendly, local domain server about it.

Why are there two methods, when one would do? Well, we're in process of
converting from method one to method two. Or rather, some of us are.
You see, there are two major communities in the ARPA Internet:  The
ARPANET and the MILNET. The ARPANET is a research network where
researchers play with networking ideas and are allowed (within reason)
to play hob with network configuration, protocols, traffic, etc. The
MILNET is a production computer network (i.e. high reliability,
availability, stable, etc.).

Those of us on ARPANET are required to convert to domains. Those of us
on MILNET are expected to watch, and follow the ARPAnauts later on when
the Defense Data Network Program Management Office (DDN-PMO) specifies
a schedule for conversion.

What's this domain stuff anyway? Well, there are several thousand hosts
on the ARPA Internet, and it's getting to be a pain for the NIC to
maintain a master host table. The idea behind domains is that every
organization maintains its own section of the host table, and tells the
rest of the world about it (upon request) through a `domain server.'

Neat huh? A giant distributed database. Thank DARPA that we have
56Kbaud trunk lines...

But those MILNET people aren't doing that yet... and what about all
those hosts that Berkeley, and MIT, and CMU, and Stanford, and ... that
haven't been registered with the NIC in the master host table?

We have the technology, we can reply: `%' (which is to say, we hide
unregistered hosts in the `local-part,'  giving:

	luser%unreg-host@berkeley.edu

that way those sites that don't use the domain server yet (and
therefore can't ask berkeley about them) have never heard of this funny
host (but have heard of Berkeley.edu) can look up the host name to the
left of the @ in the hosts.txt file and get mail there). That percent
hack has to stay until either:

	1. ALL hosts on the internet are registered in the NIC host table.
	2. we *all* convert to domainism.

Number 1 is unlikely to happen, since the NIC is already overloaded.
Number 2 will happen, eventually, if domainism isn't a total flop.
So far, it works OK.

It should be noted that domainism is a very fundamental change from the
old ways of doing things, and that they're still working out the bugs.

	hope this was clear,

	Erik E. Fair	styx!fair	fair@lll-tis-b.arpa
			ucbvax!fair	fair@ucbarpa.berkeley.edu