Resolution of Uniform Resource Identifiers using the Domain Name System (RFC2168)
Original Publication Date: 1997-Jun-01
Included in the Prior Art Database: 2000-Sep-13
Internet Society Requests For Comment (RFCs)
R. Danie1: AUTHOR [+2]
Status of this Memo ===================
Network Working Group R. Daniel
Request for Comments: 2168 Los Alamos National Laboratory
Category: Experimental M. Mealling
Network Solutions, Inc.
Resolution of Uniform Resource Identifiers
using the Domain Name System
Status of this Memo
This memo defines an Experimental Protocol for the Internet
community. This memo does not specify an Internet standard of any
kind. Discussion and suggestions for improvement are requested.
Distribution of this memo is unlimited.
Uniform Resource Locators (URLs) are the foundation of the World Wide
Web, and are a vital Internet technology. However, they have proven
to be brittle in practice. The basic problem is that URLs typically
identify a particular path to a file on a particular host. There is
no graceful way of changing the path or host once the URL has been
assigned. Neither is there a graceful way of replicating the resource
located by the URL to achieve better network utilization and/or fault
tolerance. Uniform Resource Names (URNs) have been hypothesized as a
adjunct to URLs that would overcome such problems. URNs and URLs are
both instances of a broader class of identifiers known as Uniform
Resource Identifiers (URIs).
The requirements document for URN resolution systems defines the
concept of a "resolver discovery service". This document describes
the first, experimental, RDS. It is implemented by a new DNS Resource
Record, NAPTR (Naming Authority PoinTeR), that provides rules for
mapping parts of URIs to domain names. By changing the mapping
rules, we can change the host that is contacted to resolve a URI.
This will allow a more graceful handling of URLs over long time
periods, and forms the foundation for a new proposal for Uniform
In addition to locating resolvers, the NAPTR provides for other
naming systems to be grandfathered into the URN world, provides
independence between the name assignment system and the resolution
protocol system, and allows multiple services (Name to Location, Name
to Description, Name to Resource, ...) to be offered. In conjunction
with the SRV RR, the NAPTR record allows those services to be
replicated for the purposes of fault tolerance and load balancing.
Uniform Resource Locators have been a significant advance in
retrieving Internet-accessible resources. However, their brittle
nature over time has been recognized for several years. The Uniform
Resource Identifier working group proposed the development of Uniform
Resource Names to serve as persistent, location-independent
identifiers for Internet resources in order to overcome most of the
problems with URLs. RFC-1737  sets f...