🚀 go-pugleaf

In article <ku70m3INNi37@early-bird.think.com> barmar@think.com (Barry Margolin) writes:
>In article <1992Apr8.164249.10851@husc3.harvard.edu> utterbac@husc10.harvard.edu (Margot Utterback) writes:
>I believe one of the original reasons for CNAMEs was to ease the migration
>from the pre-DNS host names to the DNS host names.  When a machine was
>switched to using a DNS name, its old name would be left as a nickname.
>The expectation was that many of these nicknames would be temporary.  They
>wanted to prevent these transient names from being captured in many
>peoples' mail files.  The assumption is that the primary name is likely to
>stick around longer.


Well, CNAME has uses beyond just that one.

For instance ... it supports `resource discovery' (of a limited sense)
with the advantage that the administrator can move the *location* of
the resource without the users having to reconfigure anything.

Concrete example:

You have a system with an e-mail -> FAX gateway installed.  You point people
to the FAX machine by telling them to send to 

	phone-number@fax-gateway.local.dom.ain

In your DNS you install CNAME records which map fax-gateway to the
system providing the real service.  If that machine breaks or is
upgraded or otherwise has to change its name, noooo problem.

You can repeat this solution `n' times.  The most common use might
be a distributed BSD/lpr environment.  Printers, after all, are a
touch more likely to move around than fax-gateway's...

It is also useful to have abbreviations for systems so you don't
have to remember to type

	rlogin herkimer
when	rlogin he

will do....



To answer the original question: having the e-mail system ignore CNAME's
and other forms of host-aliasing is bogus, IMO.  Regardless of what
it says in RFC-822 (remember, 822 is rather old) from a usability standpoint
it is silly and anal-retentive to require addresses to not be an alias.
The HR RFC likely has (nicer) words to this effect.

	David


-- 
<- David Herron, an MMDF & WIN/MHS guy, <david@twg.com>
<-
<- As for the prevalence of gratuitous stupidity in modern life, well,
<- need I say more than "MS-DOS"? -- Bill Janssen