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From André Warnier>
Subject Re: Subdomains and Wars...
Date Wed, 21 Oct 2009 21:10:41 GMT
Tony Anecito wrote:
> Hi Andre,
> Here is an article that talks about subdomain usage. I hope it helps explain the concept
better for all.
that article is a terrible mixture of truths, half-truths, and downright 
bull.  The author of that article should at least read the relevant 
Internet RFCs, instead of leading unsuspecting users into confusion.

If you are interested in the proper terminology for these things, here 
is a good index :
(start with RFC 1034)

For instance :
".com" is a domain, and it happens to be a "top-level domain".
"" and "" are also domains, and they are both subdomains of 
"" and "" and "" are all domains; all three 
are also sub-domains of ".com", and the first 2 are also sub-domains of 
"" may also be a domain; or it may be an alias of 
"", and it may be a hostname to boot. Or not.

What I am trying to say, is that what you are talking about, are 
hostnames and/or hostname aliases, not "subdomains".  In an Tomcat 
configuration file, you will find tags such as "<Host>" and "<Alias>". 
and not "<Subdomain>", and rightly so.
Similarly in Apache httpd you will find "ServerName" and "ServerAlias".
These things have a precise meaning, which subdomain has not.
Using the term "subdomain" in this context is vague, confusing, and 

As per RFC 1034 § 3.1 :

A domain is identified by a domain name, and consists of that part of
the domain name space that is at or below the domain name which
specifies the domain.  A domain is a subdomain of another domain if it
is contained within that domain.  This relationship can be tested by
seeing if the subdomain's name ends with the containing domain's name.
For example, A.B.C.D is a subdomain of B.C.D, C.D, D, and " ".

That's it.  That is what "subdomain" means. No more and no less.

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