What is a full qualified hostname?

[Gary W. Swearingen]

"John DeCarlo" <johndecarlo at gmail.com> writes:

> I suspect that they want a domain that can actually have mail sent to it.
>
> That requires something like flashhost.com or flashhost.de
>
> If you are not connected to the Internet, you can make one up and put the
> FQDN in your /etc/hosts file.

Often, the conventional "localhost" is a good enough FQDN (it is a
top-level domain name), but some software (e.g., sendmail) seems to
require something with a dot; then "localhost.localhost" works (and
seemed to be suggested by one RFC I was reading), but
"localhost.localdomain" is more popular, probably.  They recommend you
don't try to make one domain names except those per RFC-2606
(http://rfc.net/rfc2606.html), namely those that are or end with
"test", "example", "invalid", "localhost" or one of "example.com",
"example.net", "example.org".