Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!mailrus!tut.cis.ohio-state.edu!osu-cis!att!cbnews!mark
From: mark@cbnews.ATT.COM (Mark Horton)
Newsgroups: comp.mail.uucp
Subject: parks and MX records
Message-ID: <1052@cbnews.ATT.COM>
Date: 1 Sep 88 20:34:22 GMT
Organization: AT&T Bell Laboratories, Columbus
Lines: 33

>>I would maintain that there is a lot of interest in parks.  They are
>>what was intended by the MX system in the first place.  No one wanted
>>every measley PC running UUPC to get an MX record!  That is an abuse
>>of the nameservers, and a disservice to the community.
>
>Er, how's that? The only site that could possibly be inconvenienced by
>a lot of MX records is the site where the nameserver database is stored.
>Each site in a domain may have a unique entry, or maybe there's a
>wildcard record. In either case, a query will use exactly the same amount
>of network bandwidth.

While the size of the nameserver database is a concern, a far more
important concern is the load on the forwarders.  A typical forwarder
implements forwarding for each domain by adding a line to sendmail.cf.
If there are more than a few dozen such lines, the sendmail.cf file
gets large, and more of a problem, mail gets slow, since sendmail.cf
is processed sequentially for each piece of mail.  Thus, forwarders
are a critical resource.  Several forwarders are running software that
is smarter, but this require an enhanced sendmail or the equivalent.

Another potentially high cost for a second level domain is inter-network
coordination.  If you consider the four major American academic networks:
DDN, CSNET, BITNET, and UUCP, using the domain system independently,
these networks are sharing the 2nd level name space under COM, EDU, GOV,
MIL, ORG, and NET.  In theory, each of them should have a full list of
each others 2nd level domains, so they know which net to forward a piece
of mail to.  In practice, most of these get bumped upstairs to DDN as
the ultimate authority, until we get something better working.

By using parks, we can get several small organizations under one 2nd
level domain.  The costs above go with 2nd level domains, so there is
an economy of scale.

	Mark