Change of FQDN

[Gary W. Swearingen]

Aaron Peterson <dopplecoder at gmail.com> writes:

> hostname="www.mydomain.com"

Say I have two Ethernet ports and I'd like to be gary.mydomain.com on
one and gary2.mydomain.com or gary.mydomain2.com on the other; then
what?

A computer's domain name is set in several places -- not always the
same values.  Most commonly they're in DNS servers and /etc/hosts and,
of course, the computer's kernel as set by the "hostname" command (eg,
using /etc/rc.conf's "hostname" variable).  But since there's only one
"hostname" setting, which can't always match all the others, it's
never made sense to me to set "hostname" to any public Internet domain
name.  (And I never have, IIRC.)

And according to BCP-32, at http://www.rfc-editor.org/rfc/rfc2606.txt,
"localhost" is the traditional top-level domain name "pointing to the
loop back IP address" (which I think of as the 127/24 network), and it
should be used to help keep broken DNS software from using any bogus
domain on the Internet except well-known ones like "localhost".

Though the "hostname" command allows use of a top-level domain, other
software doesn't (eg, "sendmail"), so it seems that a good domain is
"something.localhost", where "something" may be "localhost", which
might avoid some problems with broken software, or something more
creative and maybe assigned uniquely to each of a group of computers.
It is not used in the public (or maybe even a private) DNS system,
except as an identifier for log files.

Am I missing something?  It's quite likely.  What other software
than sendmail needs my single "hostname" and when?