Hosting multiple TLDs

Jonathan de Boyne Pollard J.deBoynePollard at Tesco.NET
Mon Sep 15 14:23:17 UTC 2003


JdeBP> That is _good_ practice.  _Best_ practice is for all of the
JdeBP> intermediate domain names to be subdomains of the domain 
JdeBP> being delegated itself.  (For example, all of the 
JdeBP> intermediate domain names used in the delegation of "gwu.edu."
JdeBP> would be subdomains of "gwu.edu." itself.)

BM> While that may be nice, it's highly impractical in many cases.

False.  You are conflating ownership of the intermediate domain name itself
with ownership of the IP address that it maps to.

BM> Don't forget another best practice: having nameservers with 
BM> few common points of failure.  Many organizations implement 
BM> this getting slave DNS service from their ISP or some other 
BM> third party.  The slave DNS provider's servers are virtually 
BM> never in the customer's domain, and often not even in the 
BM> same TLD (if they're an ISP they're likely to have a .NET 
BM> domain).

And this is where you are doing it.  Furthermore, the good practice that you
cite is irrelevant to this discussion and a red herring, because it doesn't
actually conflict with the best practice that I gave at all.

The servers run by the hosting company do not have _IP addresses_ that are
owned by the customer.  (And it is the IP addresses to which the "common
points of failure" concerns that you allude to apply.)  The ownership of the
domain names that they have is an entirely different matter.  You are
conflating ownership of the intermediate domain names with ownership of the IP
addresses.

Indeed, there's not really a proper notion of those servers being "in" a
single specific domain, the customer's or another, at all; so your argument
that they are "in" one domain to the exclusion of being "in" any other has no
concrete foundation.  The intermediate domain names used in the delegation of
the customer's domain are usage-specific domain names.  Their existence
doesn't make the servers (whose IP addresses they map to) "in" the domain that
they are subdomains of.  Neither (now that Verisign has lifted its erstwhile
restriction) are the servers precluded from having many such intermediate
domain names.  (Moreover, the existence of those other intermediate domain
names doesn't make the servers "in" those other domains, either.)

BM> Do you really expect ISP's and other DNS providers to have
BM> servers in every potential TLD?

That question is a leading question that implies the false premise that one
needs a separate server for each domain, and is thus unanswerable.  You are
erroneously thinking that there's a one-to-one mapping between an intermediate
domain name, used in a delegation, and a server.  There isn't.  (The mapping
is many-to-one, sometimes even many-to-many.)

You are erroneously thinking that the intermediate domain names used in
delegations must be general purpose names for the machines in question.  They
aren't.  (Intermediate domain names can, and for best results should, be
considered usage-specific aliases.)

You are erroneously thinking that the same, single, intermediate domain name
must be used for any given server in _every_ delegation that points to that
server.  It need not.


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