IAB Technical Comment on the Unique DNS Root
RFC 2826
Network Working Group Internet Architecture Board
Request for Comments: 2826 May 2000
Category: Informational
IAB Technical Comment on the Unique DNS Root
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2000). All Rights Reserved.
Summary
To remain a global network, the Internet requires the existence of a
globally unique public name space. The DNS name space is a
hierarchical name space derived from a single, globally unique root.
This is a technical constraint inherent in the design of the DNS.
Therefore it is not technically feasible for there to be more than
one root in the public DNS. That one root must be supported by a set
of coordinated root servers administered by a unique naming
authority.
Put simply, deploying multiple public DNS roots would raise a very
strong possibility that users of different ISPs who click on the same
link on a web page could end up at different destinations, against
the will of the web page designers.
This does not preclude private networks from operating their own
private name spaces, but if they wish to make use of names uniquely
defined for the global Internet, they have to fetch that information
from the global DNS naming hierarchy, and in particular from the
coordinated root servers of the global DNS naming hierarchy.
1. Detailed Explanation
There are several distinct reasons why the DNS requires a single root
in order to operate properly.
1.1. Maintenance of a Common Symbol Set
Effective communications between two parties requires two essential
preconditions:
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RFC 2826 IAB Technical Comment on the Unique DNS Root May 2000
- The existence of a common symbol set, and
- The existence of a common semantic interpretation of these
symbols.
Failure to meet the first condition implies a failure to communicate
at all, while failure to meet the second implies that the meaning of
the communication is lost.
In the case of a public communications system this condition of a
common symbol set with a common semantic interpretation must be
further strengthened to that of a unique symbol set with a unique
semantic interpretation. This condition of uniqueness allows any
party to initiate a communication that can be received and understood
by any other party. Such a condition rules out the ability to define
a symbol within some bounded context. In such a case, once the
communication moves out of the context of interpretation in which it
was defined, the meaning of the symbol becomes lost.
Within public digital communications networks such as the Internet
this requirement for a uniquely defined symbol set with a uniquely
defined meaning exists at many levels, commencing with the binary
encoding scheme, extending to packet headers and payload formats and
the protocol that an application uses to interact. In each case a
variation of the symbol set or a difference of interpretation of the
symbols being used within the interaction causes a protocol failure,
and the communication fails. The property of uniqueness allows a
symbol to be used unambiguously in any context, allowing the symbol
to be passed on, referred to, and reused, while still preserving the
meaning of the original use.
The DNS fulfills an essential role within the Internet protocol
environment, allowing network locations to be referred to using a
label other than a protocol address. As with any other such symbol
set, DNS names are designed to be globally unique, that is, for any
one DNS name at any one time there must be a single set of DNS
records uniquely describing protocol addresses, network resources and
services associated with that DNS name. All of the applications
deployed on the Internet which use the DNS assume this, and Internet
users expect such behavior from DNS names. Names are then constant
symbols, whose interpretation does not specifically require knowledge
of the context of any individual party. A DNS name can be passed
from one party to another without altering the semantic intent of the
name.
Since the DNS is hierarchically structured into domains, the
uniqueness requirement for DNS names in their entirety implies that
each of the names (sub-domains) defined within a domain has a unique
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RFC 2826 IAB Technical Comment on the Unique DNS Root May 2000
meaning (i.e., set of DNS records) within that domain. This is as
true for the root domain as for any other DNS domain. The
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