Decreasing Access Time to Root Servers by Running One on Loopback
RFC 7706

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Internet Engineering Task Force (IETF)                         W. Kumari
Request for Comments: 7706                                        Google
Category: Informational                                       P. Hoffman
ISSN: 2070-1721                                                    ICANN
                                                           November 2015

   Decreasing Access Time to Root Servers by Running One on Loopback

Abstract

   Some DNS recursive resolvers have longer-than-desired round-trip
   times to the closest DNS root server.  Some DNS recursive resolver
   operators want to prevent snooping of requests sent to DNS root
   servers by third parties.  Such resolvers can greatly decrease the
   round-trip time and prevent observation of requests by running a copy
   of the full root zone on a loopback address (such as 127.0.0.1).
   This document shows how to start and maintain such a copy of the root
   zone that does not pose a threat to other users of the DNS, at the
   cost of adding some operational fragility for the operator.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7706.

Kumari & Hoffman              Informational                     [Page 1]
RFC 7706                Running Root on Loopback           November 2015

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Notation . . . . . . . . . . . . . . . . . .   4
   2.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Operation of the Root Zone on the Loopback Address  . . . . .   5
   4.  Using the Root Zone Server on the Loopback Address  . . . . .   6
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Appendix A.  Current Sources of the Root Zone . . . . . . . . . .   8
   Appendix B.  Example Configurations of Common Implementations . .   8
     B.1.  Example Configuration: BIND 9.9 . . . . . . . . . . . . .   9
     B.2.  Example Configuration: Unbound 1.4 and NSD 4  . . . . . .  10
     B.3.  Example Configuration: Microsoft Windows Server 2012  . .  11
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

Kumari & Hoffman              Informational                     [Page 2]
RFC 7706                Running Root on Loopback           November 2015

1.  Introduction

   DNS recursive resolvers have to provide answers to all queries from
   their customers, even those for domain names that do not exist.  For
   each queried name that has a top-level domain (TLD) that is not in
   the recursive resolver's cache, the resolver must send a query to a
   root server to get the information for that TLD, or to find out that
   the TLD does not exist.  Typically, the vast majority of queries
   going to the root are for names that do not exist in the root zone,
   and the negative answers are cached for a much shorter period of
   time.  A slow path between the recursive resolver and the closest
   root server has a negative effect on the resolver's customers.

   Recursive resolvers currently send queries for all TLDs that are not
   in their caches to root servers, even though most of those queries
   get answers that are referrals to other servers.  Malicious third
   parties might be able to observe that traffic on the network between
   the recursive resolver and one or more of the DNS roots.