looking for terminology recommendations concerning non-rooted FQDNs

Sat Feb 23 03:27:18 UTC 2013

On 2/21/13, Mark Andrews <marka at isc.org> wrote:
> RFC 952 as modified by RFC 1123 describe the legal syntax of a hostname.
> There is no trailing period.

A hostname is not a domain name,  the hostname is just a label, and
has stricter syntax than is allowed in a DNS label; however:  When
hostnames are represented in DNS, they have corresponding domain
names. eg for A.example.com

The domain name is unqualified if it contains just the hostname  "A".
It is partially qualified,  if a subset of the labels are provided   "A.example"

The names are called fully qualified, when the domain name shown is
the complete DNS name, with all labels;   "A.example.com"

In the DNS,  the implicit trailing dot is understood to be part of the
domain name.

Technically  "A.example.com"   without a trailing dot is unqualified,
for purposes of DNS resolution;  if  a DNS resolver receives NXDOMAIN
for  A.example.com;    some resolvers   will   normally search for
A.example.com.suffix   next

However, it is nevertheless commonly referred to as fully-qualified,
with or without the trailing dot,  even though syntactically it could
be unqualified;  because  ".COM"  is such a well-known TLD  .

In this case, it doesn't actually matter what the RFCs  call a FQDN;
it's overridden by common usage  of the  phrase/acronym  (It is
commonly understood that no trailing dot is required, except   in  the
context of a zone file).

There is little understanding about qualification of hostnames, and
DNS resolver search,  and these concepts should probably just go away
/ be simplified,   so all valid lookup names are FQDNs or  local
hostnames with no dots.

>> --
>> Brian Reichert				<reichert at numachi.com>
>> BSD admin/developer at large	
>>
> --
> Mark Andrews, ISC
> 1 Seymour St., Dundas Valley, NSW 2117, Australia
> PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org

--
-JH