RFC 2915 (rfc2915) - Page 2 of 18
The Naming Authority Pointer (NAPTR) DNS Resource Record
Alternative Format: Original Text Document
RFC 2915 NAPTR DNS RR September 2000
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. NAPTR RR Format . . . . . . . . . . . . . . . . . . . . . . 3
3. Substitution Expression Grammar . . . . . . . . . . . . . . 7
4. The Basic NAPTR Algorithm . . . . . . . . . . . . . . . . . 8
5. Concerning How NAPTR Uses SRV Records . . . . . . . . . . . 9
6. Application Specifications . . . . . . . . . . . . . . . . . 10
7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.1 Example 1 . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.2 Example 2 . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.3 Example 3 . . . . . . . . . . . . . . . . . . . . . . . . . 13
8. DNS Packet Format . . . . . . . . . . . . . . . . . . . . . 13
9. Master File Format . . . . . . . . . . . . . . . . . . . . . 14
10. Advice for DNS Administrators . . . . . . . . . . . . . . . 14
11. Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . 15
13. Security Considerations . . . . . . . . . . . . . . . . . . 15
14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 16
References . . . . . . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 17
Full Copyright Statement . . . . . . . . . . . . . . . . . . 18
1. Introduction
This RR was originally produced by the URN Working Group [3] as a way
to encode rule-sets in DNS so that the delegated sections of a URI
could be decomposed in such a way that they could be changed and re-
delegated over time. The result was a Resource Record that included
a regular expression that would be used by a client program to
rewrite a string into a domain name. Regular expressions were chosen
for their compactness to expressivity ratio allowing for a great deal
of information to be encoded in a rather small DNS packet.
The function of rewriting a string according to the rules in a record
has usefulness in several different applications. This document
defines the basic assumptions to which all of those applications must
adhere to. It does not define the reasons the rewrite is used, what
the expected outcomes are, or what they are used for. Those are
specified by applications that define how they use the NAPTR record
and algorithms within their contexts.
Flags and other fields are also specified in the RR to control the
rewrite procedure in various ways or to provide information on how to
communicate with the host at the domain name that was the result of
the rewrite.
Mealling & Daniel Standards Track