looking for terminology recommendations concerning non-rooted FQDNs

Sat Feb 23 04:26:58 UTC 2013

On 2/22/13, Jay Ashworth <jra at baylink.com> wrote:

RFC103 5.1 is correct in the context of a DNS zonefile.
In other contexts, however, a domain is absolute without a trailing dot.
One example,  would be in the case of the SMTP protocol,  where
hostnames are required to  _always_  be absolute.

In various common contexts,  a domain is  always either fully
qualified,  or not valid.

Sometimes a trailing dot is allowed,  and in some protocols, a
trailing dot is not allowed;  however the domain used is still called
a FQDN;  it's just different syntax, for a fqdn,  with minor
variations..

A trailing dot is not included in the domain portion of an e-mail
address, however   within the context of  nobody at example.com;
example.com  is  understood to be a fully qualified domain.

Nothing else really makes sense;  "example.com"  is absolute and not
relative in this context..

It is also true in the context of a http URL scheme    http://www.example.com/

In that context, the www.example.com  is a fully qualified domain;
although some browsers
might try appending  other suffixes,  as an aid to the user,  if  the
domain cannot be found.

No trailing dot allowed; "each domain label starting and ending with
an alphanumerical character";

The URL  is the most common context  where a fully qualified domain
would be encountered,   e-mail addresses and URLs  are  the most
common case where the average network user will encounter a domain
name.

For the sake of consistency,  if  something is  considered a FQDN in a
URL and in a SMTP hostname or e-mail address,  then  it ought to be
made to be considered a fully qualified domain, everywhere.

"
Berners-Lee, Masinter & McCahill                                [Page 5]

RFC 1738            Uniform Resource Locators (URL)        December 1994

 host
        The fully qualified domain name of a network host, or its IP
        address as a set of four decimal digit groups separated by
        ".". Fully qualified domain names take the form as described
        in Section 3.5 of RFC 1034 [13] and Section 2.1 of RFC 1123
        [5]: a sequence of domain labels separated by ".", each domain
        label starting and ending with an alphanumerical character and
        possibly also containing "-" characters. The rightmost domain
        label will never start with a digit, though, which
        syntactically distinguishes all domain names from the IP
        addresses.
"

> The authoritative document here is, as Joe Abley noted earlier, RFC 1035,
> which says, in section 5.1:
>
> """
> Domain names that end in a dot are called absolute, and are taken as
> complete.  Domain names which do not end in a dot are called relative;
> the actual domain name is the concatenation of the relative part with
> an origin specified in a $ORIGIN, $INCLUDE, or as an argument to the
> master file loading routine.  A relative name is an error when no
> origin is available.
> """

> Jay R. Ashworth                  Baylink
-- 
-JH