From: jik@athena.mit.edu (Jonathan I. Kamens)
Newsgroups: news.admin
Subject: Re: Getting address from server name [Q]
Date: 7 Apr 92 13:57:34 GMT
Article-I.D.: pit-mana.JIK.92Apr7095731
Distribution: na
Organization: Massachusetts Institute of Technology

In article <1992Apr7.080404.4808@cs.uri.edu> reynhout@cs.uri.edu writes:

      Is there a standard way to discern a machine's address, given its entry
   in the path header of an article?

What do you mean by "address?"  Do you mean a mail address that will
successfully get mail delivered to it, or the IP address associated
with the host?

There are several types of addresses listed in UUCP Path lines:

1) Fully qualified domain names (FQDNs) (e.g. "server.cs.uri.edu" of
   machines that are either directly on the Internet or have an MX
   record pointing to a host that is directly on the Internet.  The
   two requirements of FQDNs in Path lines is that they are registered
   in the DNS hierarchy and there's some way to get mail to them
   (well, *actually*, I guess you could have an FQDN in a Path line
   without any way to get mail to it, but it BETTER be registered in
   the DNS).

2) FQDNs that aren't registered in the DNS.  The admins of these sites
   should be taken out back and shot, because they might conflict at
   some later date with a host with the same name that *does* register
   itself with the DNS.

3) UUCP host names (these are names with one component, rather than
   domain names with periods in them) of hosts that are registered in
   the UUCP maps in comp.mail.maps, and that can be reached only
   through their UUCP feeds listed in comp.mail.maps.

4) UUCP host names that are registered in the UUCP maps, but that have
   DNS FQDNs corresponding to them; these FQDNs can usually be used to
   deliver mail without using UUCP paths.

5) UUCP host names that are not registered in the UUCP maps.  Again,
   the admins of these sites should be taken out back and shot.

The only way to be able to guarantee mail delivery to as many of the
types of hosts listed above as possible, you need to either (a) use
pathalias to build a list of UUCP paths from your site, and hack your
mailer to know how to use the pathalias maps for routing, or (b) find
a site that knows how to do pathalias routing, and forward all
UUCP-path mail to them for routing and delivery.

If you're talking about finding IP addresses, then if the host is
already an FQDN, you can simply use a program such as nslookup to find
its IP address.  If it isn't, you have to check in the UUCP maps to
see if there is a FQDN associated with it.

      My server is called "server.cs.uri.edu", making it very easy.  Others 
   are not so simple, and some are incomprehensible.  I don't recall registering
   my server name when I decided what to call it, so perhaps this is merely 
   wishful thinking.

You don't need to register DNS FQDNs anywhere.  The DNS is the
"registry."  That's why it's considered a crime to use a FQDN that
isn't in the DNS.

      I can, of course, work backwards -- contact my feed (or the furthest-back
   which I can figure out the address for) and ask them to identify a given 
   server name, then repeat this procedure until I get the address I'm looking
   for.  Is this the ONLY way?

No, look in comp.mail.maps.  See "UUCP map for README" in that
newsgroup.

-- 
Jonathan Kamens						jik@MIT.Edu
MIT Information Systems/Athena		    Moderator, news.answers
    (Send correspondence related to the news.answers newsgroup
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