Xref: utzoo comp.protocols.tcp-ip.domains:381 comp.mail.uucp:5151
Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!ucsd!nosc!logicon.com!Makey
From: Makey@Logicon.COM (Jeff Makey)
Newsgroups: comp.protocols.tcp-ip.domains,comp.mail.uucp
Subject: Domain names in the UUCP Map
Message-ID: <767@logicon.com>
Date: 11 Sep 90 01:05:49 GMT
Organization: Logicon, Inc., San Diego, California
Lines: 110
For sites where the policy is to send mail via the internet whenever
possible, I have been working on modifications to the the "pathalias"
program to allow it to produce a UUCP Zone file for the DNS (Domain
Name System). Following is a summary of the results of my first test
against the entire UUCP Map.
Resolving thousands of domain names takes time, and the program ran
for almost 4 hours late at night on a lightly loaded VAX-11/780 with a
56 kilobaud MILNET connection. Having a name server that caches
negative replies would have helped a bit.
There were 341 host names or aliases in the UUCP Map that have the
appearance of being domain names (i.e., containing at least one dot)
but in fact are not registered domain names. Most notable were the 35
entries in the bogus top-level domain .cdn, which apparently refers to
the CDNnet network in Canada.
There were 38 DNS lookup failures. I expected to have trouble with
some of the European domains, but the IP gateways must have been in a
good mood that night.
There were 2567 CNAME records generated for hosts with DNS MX and/or A
records, such as:
uunet IN CNAME uunet.uu.net.
There were 3540 MX records generated for sites 1 hop off the internet,
such as:
utzoo IN MX 95 gpu.utcs.toronto.edu.
The precedence for the MX record is the cost as computed by pathalias
from the forwarding internet host to the UUCP host. MX records are
generated only when the cost is 64535 (the maximum value allowed in
the MX precedence field by bind 4.8) or less. The top 5 MX hosts are:
internet host name number of MX neighbors
----------------------------------------------
uunet.uu.net 1027
unido.informatik.uni-dortmund.de 218
hp4nl.nluug.nl 124
inria.inria.fr 79
sun.com 73
There were 7294 host names or aliases in the UUCP Map for which
neither CNAME nor MX records were generated. An internet-rooted
pathalias output for them was produced, with each route beginning with
a host with a DNS A or MX record, such as:
kremvax oliveb.atc.olivetti.com!tolsoft!namei!walldrug!kremvax!%s
An unmodified version of pathalias produced 19102 UUCP routes from the
same map data. Subtracting the 2567 CNAME records (13% of the total),
3540 MX records (19%), and 7294 remaining routes (38%) leaves 5701
host names or domains (30%) in the UUCP Map that can be resolved via
the DNS.
The standard pathalias output had an average hop count of 4.7 with a
standard deviation of 0.9, and a maximum hop count of 10. Virtually
all of my first hops were to ucsd, a well-connected site in San Diego.
Your mileage will vary. The list of internet-rooted paths had an
average hop count of 2.7 with a standard deviation of 0.7, and a
maximum hop count of 7 (this does not take into account the fact that
MX-only hosts are really 2 hops away).
I am pleased by the results so far. To speed things up I want to make
changes to the resolver code to allow multiple DNS queries in
parallel, but other than that the program is nearly done. Look for
the required patches to pathalias in a sources newsgroup near you in a
couple of weeks.
Certain social issues should be resolved before the use of this
program and its output becomes too widespread. Number one on the list
is what the origin of the zone file should be. The obvious choice --
UUCP -- would get the Protocol Police extremely upset, but anything
else would make all of those wonderful MX records cause more trouble
than they solve. Somewhat less ideal, but still satisfactory, would
be for the benevolent administrator of some established domain to
provide a subdomain (e.g., UUCP.FOO.COM) just for this data. A
long-term commitment to such service would be required to prevent
scattered outbreaks of the next alternative: In the absence of a
DNS-wide standard, individual sites are sure to DWTDWP (Do Whatever
They Damn Well Please), which would result in a lot of unnecessary DNS
traffic net-wide as they each periodically resolve some 6000 domain
names. No doubt there would also be an increase in the number of
local unofficial UUCP top-level domains in the DWTDWP case.
If a few sites that run smail volunteered, wildcard MX records
pointing to them could be added to the zone file to take care of all
of those sites that are more than 1 hop off the internet. The rest of
the internet sites would no longer have to worry about the UUCP Map at
all.
If there is sufficient interest, and if we can't get our collective
act together and put this data into a publicly-available zone, a
single site could periodically generate the zone file and
internet-rooted paths and post them to an appropriate newsgroup with
"inet" distribution. (Together they currently consume about half a
megabyte of disk space.) This approach would probably make better use
of internet resources than having lots of sites banging away at the
DNS.
This is submitted for your information. I am just a postmaster who
wants to make the most of the DNS.
:: Jeff Makey
Department of Tautological Pleonasms and Superfluous Redundancies Department
Disclaimer: All opinions are strictly those of the author.
Internet: Makey@Logicon.COM UUCP: {nosc,ucsd}!logicon.com!Makey