From: HERBER@fnalf.fnal.gov (Randolph J. Herber, CD/DCD/USS, x2966)
Newsgroups: comp.sys.sgi
Subject: RE: Mail ingenuity
Date: 14 Sep 92 21:48:04 GMT

Hi Jim!

If you submitted these commands to `nslookup':
	set query=any
	set verbose
	tuns.ca.
	lserver newton.ccs.tuns.ca.
	tuns.ca.
	exit
	
You would have received a report similiar to this: (note the ==> flagged line!)
	Default Server:  LOCALHOST
	Address:  127.0.0.1
	
	> set query=any
	> set verbose
	> tuns.ca.
	Server:  LOCALHOST
	Address:  127.0.0.1
	
	Non-authoritative answer:
	tuns.ca	nameserver = newton.ccs.tuns.ca
	tuns.ca	nameserver = taurus.cs.tuns.ca
	tuns.ca	nameserver = mars.csd.unb.ca
	
	Authoritative answers can be found from:
	tuns.ca	nameserver = newton.ccs.tuns.ca
	tuns.ca	nameserver = taurus.cs.tuns.ca
	tuns.ca	nameserver = mars.csd.unb.ca
	newton.ccs.tuns.ca	internet address = 134.190.1.4
	taurus.cs.tuns.ca	internet address = 134.190.11.4
	mars.csd.unb.ca	internet address = 131.202.1.3
	> lserver newton.ccs.tuns.ca.
	Default Server:  newton.ccs.tuns.ca
	Address:  134.190.1.4
	
	> tuns.ca.
	Server:  newton.ccs.tuns.ca
	Address:  134.190.1.4
	
	tuns.ca
		origin = newton.ccs.tuns.ca
		mail addr = ejones.newton.ccs.tuns.ca
		serial = 92073101
		refresh = 7200 (2 hours)
		retry   = 1200 (20 mins)
		expire  = 1728000 (20 days)
		minimum ttl = 86400 (1 day)
	tuns.ca	nameserver = newton.ccs.tuns.ca
	tuns.ca	nameserver = taurus.cs.tuns.ca
	tuns.ca	nameserver = mars.csd.unb.ca
==>	tuns.ca	preference = 10, mail exchanger = edison.adm.tuns.ca
	newton.ccs.tuns.ca	internet address = 134.190.1.4
	taurus.cs.tuns.ca	internet address = 134.190.11.4
	mars.csd.unb.ca	internet address = 131.202.1.3
	edison.adm.tuns.ca	internet address = 134.190.1.7
	> exit

The flagged line indicates that the machine edison.adm.tuns.ca accepts mail
for the destination named tuns.ca.  `tuns.ca' does not have to be a Internet
connected machine as long as the acceptor knows how to deliver the mail.
This is the "black magic"; but, it only works for SMTP connections.

The line "zsd@tuns.ca... Connecting to edison.adm.tuns.ca (tcp)..." in the
verbose output from sendmail is attempting to tell you the same data!

A mail acceptor is not required or expected to accept other kinds of
connections on behalf of the named destination.  That is why ftp, telnet, etc.
do not work.

The `RTFM's are RFC 1034 and RFC 1035.  You can obtain them from nic.ddn.mil
via anonymous ftp in the rfcs directory as rfc1034.txt and rfc1035.txt.

Randolph J. Herber, herber@fnalf.fnal.gov, +1 708 840 2966
(Speaking for myself and not for US, US DOE, FNAL nor URA.)
(Product, trade, or service marks herein belong to their respective owners.)

+Date: Mon, 14 Sep 92 11:09:12 -0300
+From: Jim Diamond <zsd@axe.drea.dnd.ca>
+Organization: DREA, Dartmouth, Nova Scotia
+To: info-iris@BRL.MIL
+Subject: Mail ingenuity

+Perhaps one (or more) of the sendmail wizards out there may be able to
+solve the following puzzle for me:

+When I use Mail to send mail to a site "tuns.ca" everything works out
+OK:

+% Mail -v zsd@tuns.ca
+Subject: test
+testing
.
+EOT
+zsd@tuns.ca... Connecting to edison.adm.tuns.ca (tcp)...
+220 edison.adm.tuns.ca -- Server SMTP (PMDF#10424 V3.2)
+>>> HELO axe.drea.dnd.ca
+250 edison.adm.tuns.ca
+>>> MAIL From:<zsd@axe.drea.dnd.ca>
+250 Address OK.
+>>> RCPT To:<zsd@tuns.ca>
+250 zsd@tuns.ca OK.
+>>> DATA
+354 Enter mail, end with a single ".".
+>>> .
+250 Ok.
+>>> QUIT
+221 Bye received. Goodbye.


+Thus someone (sendmail?) was able to find an address for "tuns.ca".
+But if I try telnet, ftp, or nslookup I get

+% nslookup tuns.ca
+Server:  arrow.drea.dnd.ca
+Address:  192.12.62.8

+*** No address (A) records available for tuns.ca
+% telnet tuns.ca
+tuns.ca: No address associated with name
+% ftp tuns.ca
+ftp: tuns.ca: No address associated with name
+ftp> quit

+And I don't have it in my hosts, aliases or sendmail* files:

+% grep -i tuns /etc/hosts /usr/lib/aliases* /usr/lib/sendmail*
%

+I'm not running YP.  My resolv.conf looks like:
+hostresorder local bind
+nameserver 192.12.62.8
+nameserver 192.12.62.11
+nameserver 192.12.98.2
+domain drea.dnd.ca

+So: what black magic does Mail or sendmail (or whomever) use to
+associate "edison.adm.tuns.ca" with "tuns.ca"?  Why can't these other
+network programs do the same?

+I'd prefer the answer, but if anyone can point me to the correct FM to
+read, that would be as good.

+Thanks.

+			Jim Diamond
+			zsd@axe.drea.dnd.ca