On Thu July 14 2005 09:00, Robert A. Rosenberg wrote:
At 02:33 -0400 on 07/14/2005, Valdis(_dot_)Kletnieks(_at_)vt(_dot_)edu wrote
draft-klensin-rfc2821bis-00.txt structural and textual :
On Thu, 14 Jul 2005 00:58:32 EDT, "Robert A. Rosenberg" said:
being everything to the right of the @-sign). The Domain part has a
host if there are more levels than the number defined for the WhoIs
Are you sure that basing it off the whois is the proper referent for this?
Yes. I am defining "Domain" based on ownership and control of that
level (and those to the left of it) in a FQDN. For TLDs ORG/NET/COM
and other non-National TLDs this is at the 2nd level. IOW, Panix.Com
is a Domain Name and all *.Panix.Com FQDNs are owned/controlled by
the owner of Panix.Com (who can be determined from a WhoIs lookup).
What I was
pointing out (or trying to say) is that a .COM domain name is 2
levels. If there was a 3-level .COM FQDN then the first (Left Most)
level is a Hostname in the 2-level domain. Any 4 or longer .COM FQDN
still has the first level as Hostname while all other levels to the
left of the 2nd level are subdomains in that 2-level domain.
No. Some commercial entities organize their domain name space along
host.department.division.company.COM or other schemes. From the outside,
it simply is not possible to definitively state whether or not
foo.bar.baz.qxx.COM is or is not a host name (as opposed to a domain
name that does not identify a particular host) unless the name resolves
(following CNAME records) to an A record, in which case it is a host.
Bit the converse is not conclusive; some hosts might not be identifiable
via externally-visible DNS queries.
All of which is rather academic regarding the specification text. What
needs to be said is that the local-part is not to be interpreted outside
of the administrative domain of the "address" (really mailbox) domain
name. Whether such interpretation occurs at an MX host or at some other
host on the recipient side of the MX host(s), or even via some mechanism
distributed over multiple hosts within the administrative domain is
an irrelevant detail.