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Versions: (RFC 6304) 00 draft-ietf-dnsop-rfc6304bis

Network Working Group                                           J. Abley
Internet-Draft                                                 Dyn, Inc.
Obsoletes: RFC6304 (if approved)                                W. Maton
Intended status: Informational                                  DNS-OARC
Expires: August 17, 2014                               February 13, 2014


                      AS112 Nameserver Operations
                    draft-jabley-dnsop-rfc6304bis-00

Abstract

   Many sites connected to the Internet make use of IPv4 addresses that
   are not globally-unique.  Examples are the addresses designated in
   RFC 1918 for private use within individual sites.

   Devices in such environments may occasionally originate Domain Name
   System (DNS) queries (so-called "reverse lookups") corresponding to
   those private-use addresses.  Since the addresses concerned have only
   local significance, it is good practice for site administrators to
   ensure that such queries are answered locally.  However, it is not
   uncommon for such queries to follow the normal delegation path in the
   public DNS instead of being answered within the site.

   It is not possible for public DNS servers to give useful answers to
   such queries.  In addition, due to the wide deployment of private-use
   addresses and the continuing growth of the Internet, the volume of
   such queries is large and growing.  The AS112 project aims to provide
   a distributed sink for such queries in order to reduce the load on
   the corresponding authoritative servers.  The AS112 project is named
   after the Autonomous System Number (ASN) that was assigned to it.

   RFC6304 described the steps required to install a new AS112 node, and
   offered advice relating to such a node's operation.  This document
   updates that advice to facilitate the addition and removal of zones
   for which query traffic will be sunk at AS112 nodes, using DNAME,
   whilst still supporting direct delegations to AS112 name servers.

   This document obsoletes RFC6304.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-



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   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on August 17, 2014.

Copyright Notice

   Copyright (c) 2014 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.




























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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  AS112 DNS Service  . . . . . . . . . . . . . . . . . . . . . .  5
     2.1.  Approach . . . . . . . . . . . . . . . . . . . . . . . . .  5
       2.1.1.  Direct Delegation  . . . . . . . . . . . . . . . . . .  5
       2.1.2.  DNAME Redirection  . . . . . . . . . . . . . . . . . .  5
     2.2.  Zones  . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     2.3.  Nameservers  . . . . . . . . . . . . . . . . . . . . . . .  6
   3.  Installation of a New Node . . . . . . . . . . . . . . . . . .  7
     3.1.  Useful Background Knowledge  . . . . . . . . . . . . . . .  7
     3.2.  Topological Location . . . . . . . . . . . . . . . . . . .  7
     3.3.  Operating System and Host Considerations . . . . . . . . .  7
     3.4.  Routing Software . . . . . . . . . . . . . . . . . . . . .  8
     3.5.  DNS Software . . . . . . . . . . . . . . . . . . . . . . . 10
     3.6.  Testing a Newly-Installed Node . . . . . . . . . . . . . . 14
   4.  Operations . . . . . . . . . . . . . . . . . . . . . . . . . . 16
     4.1.  Monitoring . . . . . . . . . . . . . . . . . . . . . . . . 16
     4.2.  Downtime . . . . . . . . . . . . . . . . . . . . . . . . . 16
     4.3.  Statistics and Measurement . . . . . . . . . . . . . . . . 16
   5.  Communications . . . . . . . . . . . . . . . . . . . . . . . . 17
   6.  On the Future of AS112 Nodes . . . . . . . . . . . . . . . . . 18
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 19
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 20
   9.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 21
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 22
     10.2. Informative References . . . . . . . . . . . . . . . . . . 22
   Appendix A.  History . . . . . . . . . . . . . . . . . . . . . . . 25
   Appendix B.  Revision History and Venue  . . . . . . . . . . . . . 26
     B.1.  draft-jabley-dnsop-rfc6304bis-00 . . . . . . . . . . . . . 26
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 27



















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1.  Introduction

   Many sites connected to the Internet make use of IPv4 addresses that
   are not globally unique.  Examples are the addresses designated in
   [RFC1918] for private use within individual sites.

   Devices in such environments may occasionally originate Domain Name
   System (DNS) [RFC1034] queries (so-called "reverse lookups")
   corresponding to those private-use addresses.  Since the addresses
   concerned have only local significance, it is good practice for site
   administrators to ensure that such queries are answered locally
   [RFC6303].  However, it is not uncommon for such queries to follow
   the normal delegation path in the public DNS instead of being
   answered within the site.

   It is not possible for public DNS servers to give useful answers to
   such queries.  In addition, due to the wide deployment of private-use
   addresses and the continuing growth of the Internet, the volume of
   such queries is large and growing.  The AS112 project aims to provide
   a distributed sink for such queries in order to reduce the load on
   the IN-ADDR.ARPA authoritative servers [RFC5855].

   The AS112 project encompasses a loosely coordinated collection of
   independently operated name servers.  Each name server functions as a
   single node in an AS112 anycast cloud [RFC4786], and is configured to
   answer authoritatively for a particular set of nominated zones.

   The AS112 project is named after the Autonomous System Number (ASN)
   that was assigned to it (see Appendix A).






















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2.  AS112 DNS Service

2.1.  Approach

2.1.1.  Direct Delegation

   [RFC6304] describes an approach whereby zones whose traffic should be
   directed towards an AS112 sink should be directly delegated to AS112
   name servers.  Correspondingly, each AS112 node is manually
   configured to answer appropriately for those zones.

   The guidance in this document preserves this capability for the zones
   that were originally delegated in this fashion.  AS112 nodes that
   were implemented in accordance with the guidance in [RFC6304] will
   continue to provide service for those zones.

2.1.2.  DNAME Redirection

   [I-D.ietf-dnsop-as112-dname] describes a different approach whereby
   queries towards specific zones are redirected to an empty zone also
   hosted on AS112 servers, using DNAME [RFC6672].

   The guidance in this document introduces this capability, allowing
   any zone administrator to sink query traffic in AS112 infrastructure
   without requiring changes to any AS112 node.

2.2.  Zones

   To support Direct Delegation AS112 service, AS112 name servers answer
   authoritatively for the following zones, corresponding to [RFC1918]
   private-use netblocks:

   o  10.IN-ADDR.ARPA

   o  16.172.IN-ADDR.ARPA, 17.172.IN-ADDR.ARPA, ..., 31.172.IN-ADDR.ARPA

   o  168.192.IN-ADDR.ARPA

   and the following zone, corresponding to the "link local" netblock
   169.254.0.0/16 listed in [RFC5735]:

   o  254.169.IN-ADDR.ARPA

   To support DNAME Redirection AS112 service, AS112 name servers answer
   authoritatively for the following zone, as specified in
   [I-D.ietf-dnsop-as112-dname]:





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   o  EMPTY.AS112.ARPA

   To aid identification of AS112 anycast nodes, each node also answers
   authoritatively for the following zones:

   o  HOSTNAME.AS112.NET

   o  HOSTNAME.AS112.ARPA

   See Section 3.5 for the recommended contents of all these zones.

2.3.  Nameservers

   To support Direct Delegation AS112 service, the relevant zones listed
   in Section 2.2 are delegated to the two name servers BLACKHOLE-
   1.IANA.ORG (192.175.48.6) and BLACKHOLE-2.IANA.ORG (192.175.48.42).

   Additionally, the server PRISONER.IANA.ORG (192.175.48.1) is listed
   in the MNAME field of the SOA records of the IN-ADDR.ARPA zones
   served by AS112 name servers.  PRISONER.IANA.ORG receives mainly
   dynamic update queries.

   The addresses of all these name servers are covered by the single
   IPv4 prefix 192.175.48.0/24.

   To support DNAME Redirection AS112 service, the single zone
   EMPTY.AS112.ARPA is delegated to the single name server
   BLACKHOLE.AS112.ARPA (addresses TBA).  The addresses of that name
   server are covered by the single IPv4 prefix TBA, and the single IPv6
   prefix TBA.





















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3.  Installation of a New Node

3.1.  Useful Background Knowledge

   Installation of an AS112 node is relatively straightforward.
   However, experience in the following general areas may prove useful:

   o  inter-domain routing with BGP [RFC4271];

   o  DNS authoritative server operations;

   o  anycast [RFC4786] distribution of DNS services.

3.2.  Topological Location

   AS112 nodes may be located anywhere on the Internet.  For nodes that
   are intended to provide a public service to the Internet community
   (as opposed to private use), it may well be advantageous to choose a
   location that is easily (and cheaply) reachable by multiple
   providers, such as an Internet exchange point.

   AS112 nodes may advertise their service prefix to BGP peers for local
   use (analogous to a conventional peering relationship between two
   providers) or for global use (analogous to a customer relationship
   with one or more providers).

   It is good operational practice to notify the community of users that
   may fall within the reach of a new AS112 node before it is installed.
   At an Internet Exchange, local mailing lists usually exist to
   facilitate such announcements.  For nodes that are intended to be
   globally reachable, coordination with other AS112 operators is highly
   recommended.  See also Section 5.

3.3.  Operating System and Host Considerations

   Examples in this document are based on UNIX and UNIX-like operating
   systems, but other operating systems exist which are suitable for use
   in construction of an AS112 node.

   The chosen platform should include support for either cloned loopback
   interfaces, or the capability to bind multiple addresses to a single
   loopback interface.  The addresses of the name servers listed in
   Section 2.3 will be configured on these interfaces in order that the
   DNS software can respond to queries properly.

   A host that is configured to act as an AS112 anycast node should be
   dedicated to that purpose, and should not be used to simultaneously
   provide other services.  This guidance is provided due to the



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   unpredictable (and occasionally high) traffic levels that AS112 nodes
   have been seen to attract.

   System startup scripts should be arranged such that the various
   AS112-related components start automatically following a system
   reboot.  The order in which interfaces are configured and software
   components started should be arranged such that routing software
   startup follows DNS software startup, and DNS software startup
   follows loopback interface configuration.

   Wrapper scripts or other arrangements should be employed to ensure
   that the anycast service prefix for AS112 is not advertised while
   either the anycast addresses are not configured, or while the DNS
   software is not running.

3.4.  Routing Software

   AS112 nodes signal the availability of AS112 name servers to the
   Internet using BGP [RFC4271]: each AS112 node is a BGP speaker, and
   announces the prefix 192.175.48.0/24 to the Internet with origin AS
   112 (see also Section 2.3).

   The examples in this document are based on the Quagga Routing
   Suite [1] running on Linux, but other software packages exist which
   also provide suitable BGP support for AS112 nodes.

   The "bgpd.conf" file is used by Quagga's bgpd daemon, which provides
   BGP protocol support.  The router id in this example is 203.0.113.1;
   the AS112 node peers with external peers 192.0.2.1 and 192.0.2.2.
   Note the local AS number 112, and the origination of the prefix
   192.175.48.0/24 to support Direct Delegation AS112 service; the IPv4
   prefix TBA and the IPv6 prefix TBA support DNAME Redirection.



















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   ! bgpd.conf
   !
   hostname as112-bgpd
   password <something>
   enable password <supersomething>
   !
   ! Note that all AS112 nodes use the local Autonomous System
   ! Number 112, and originate the IPv4 prefixes 192.175.48.0/24
   ! and TBA and the IPv6 prefix TBA.
   !
   ! All other addresses shown below are illustrative, and
   ! actual numbers will depend on local circumstances.
   !
   ! IPv4-only or IPv6-only AS112 nodes should omit advertisements
   ! for address families they do not support.
   !
   router bgp 112
    bgp router-id 203.0.113.1
    neighbor 192.0.2.1 remote-as 64496
    neighbor 192.0.2.1 next-hop-self
    neighbor 192.0.2.2 remote-as 64497
    neighbor 192.0.2.2 next-hop-self
   !
    address-family ipv4 unicast
     network 192.175.48.0/24
     network TBA
   !
    address-family ipv6 unicast
     network TBA

   The "zebra.conf" file is required to provide integration between
   protocol daemons (bgpd, in this case) and the kernel.

   ! zebra.conf
   !
   hostname as112
   password <something>
   enable password <supersomething>
   !
   interface lo
   !
   interface eth0
   !








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3.5.  DNS Software

   Although the queries received by AS112 nodes are definitively
   misdirected, it is important that they be answered in a manner that
   is accurate and consistent.  For this reason AS112 nodes operate as
   fully-functional and standards-compliant DNS authoritative servers
   [RFC1034], and hence require appropriate DNS software.

   Examples in this document are based on ISC BIND9 [2], but other DNS
   software exists which is suitable for use in construction of an AS112
   node.

   The following is a sample BIND9 "named.conf" file for a dedicated
   AS112 server.  Note that the name server is configured to act as an
   authoritative-only server (i.e. recursion is disabled).  The name
   server is also configured to listen on the various AS112 anycast name
   server addresses, as well as its local addresses.

   // named.conf

   // global options

   options {
     listen-on {
       127.0.0.1;         // localhost

     // the following address is node-dependent, and should be set to
     // something appropriate for the new AS112 node

       203.0.113.1;       // local address (globally-unique, unicast)

     // the following addresses are used to support Direct Delegation
     // AS112 service, and are the same for all AS112 nodes

       192.175.48.1;      // prisoner.iana.org (anycast)
       192.175.48.6;      // blackhole-1.iana.org (anycast)
       192.175.48.42;     // blackhole-2.iana.org (anycast)

     // the following address is used to support DNAME Redirection
     // AS112 service, and is the same for all AS112 nodes

       TBA;               // blackhole.as112.arpa (anycast)
     };

     listen-on-v6 {
       ::1;               // localhost

     // the following address is used to support DNAME Redirection



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     // AS112 service, and is the same for all AS112 nodes

       TBA;               // blackhole.as112.arpa (anycast)
     };

     directory "/var/named";
     recursion no;        // authoritative-only server
     query-source address *;
   };

   // log queries,  so that when people call us about unexpected
   // answers to queries they didn't realise they had sent, we
   // have something to talk about.  Note that activating this
   // has the potential to create high CPU load and consume
   // enormous amounts of disk space.

   logging {
     channel "querylog" {
       file "/var/log/query.log" versions 2 size 500m;
       print-time yes;
     };
     category queries { querylog; };
   };

   // Direct Delegation AS112 Service

   // RFC 1918

   zone "10.in-addr.arpa" { type master; file "db.dd-empty"; };
   zone "16.172.in-addr.arpa" { type master; file "db.dd-empty"; };
   zone "17.172.in-addr.arpa" { type master; file "db.dd-empty"; };
   zone "18.172.in-addr.arpa" { type master; file "db.dd-empty"; };
   zone "19.172.in-addr.arpa" { type master; file "db.dd-empty"; };
   zone "20.172.in-addr.arpa" { type master; file "db.dd-empty"; };
   zone "21.172.in-addr.arpa" { type master; file "db.dd-empty"; };
   zone "22.172.in-addr.arpa" { type master; file "db.dd-empty"; };
   zone "23.172.in-addr.arpa" { type master; file "db.dd-empty"; };
   zone "24.172.in-addr.arpa" { type master; file "db.dd-empty"; };
   zone "25.172.in-addr.arpa" { type master; file "db.dd-empty"; };
   zone "26.172.in-addr.arpa" { type master; file "db.dd-empty"; };
   zone "27.172.in-addr.arpa" { type master; file "db.dd-empty"; };
   zone "28.172.in-addr.arpa" { type master; file "db.dd-empty"; };
   zone "29.172.in-addr.arpa" { type master; file "db.dd-empty"; };
   zone "30.172.in-addr.arpa" { type master; file "db.dd-empty"; };
   zone "31.172.in-addr.arpa" { type master; file "db.dd-empty"; };
   zone "168.192.in-addr.arpa" { type master; file "db.dd-empty"; };

   // RFC 5735



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   zone "254.169.in-addr.arpa" { type master; file "db.dd-empty"; };

   // DNAME Redirection AS112 Service

   zone "empty.as112.arpa" { type master; file "db.dr-empty"; };

   // also answer authoritatively for the HOSTNAME.AS112.NET and
   // HOSTNAME.AS112.ARPA zones, which contain data of operational
   // relevance

   zone "hostname.as112.net" {
     type master;
     file "db.hostname.as112.net";
   };

   zone "hostname.as112.arpa" {
     type master;
     file "db.hostname.as112.arpa";
   };

   The "db.dd-empty" file follows, below.  This is the source data used
   to populate all the IN-ADDR.ARPA zones listed in Section 2.2 that
   support Direct Delegation AS112 service.  Note that the RNAME
   specified in the SOA record corresponds to
   hostmaster@root-servers.org, a suitable e-mail address for technical
   queries about these zones.

   ; db.dd-empty
   ;
   ; Empty zone for Direct Delegation AS112 service.
   ;
   $TTL    1W
   @  IN  SOA  prisoner.iana.org. hostmaster.root-servers.org. (
                                  1       ; serial number
                                  1W      ; refresh
                                  1M      ; retry
                                  1W      ; expire
                                  1W )    ; negative caching TTL
   ;
          NS     blackhole-1.iana.org.
          NS     blackhole-2.iana.org.
   ;
   ; There should be no other resource records included in this zone.
   ;
   ; Records that relate to RFC 1918-numbered resources within the
   ; site hosting this AS112 node should not be hosted on this
   ; name server.




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   The "db.dr-empty" file follows, below.  This is the source data used
   to populate the EMPTY.AS112.ARPA zone that supports DNAME Redirection
   AS112 service.  Note that the RNAME specified in the SOA record
   corresponds to noc@dns.icann.org, a suitable e-mail address for
   technical queries about this zone.

   ; db.dr-empty
   ;
   ; Empty zone for Direct Delegation AS112 service.
   ;
   $TTL    1W
   @  IN  SOA  blackhole.as112.arpa. noc.dns.icann.org. (
                                  1       ; serial number
                                  1W      ; refresh
                                  1M      ; retry
                                  1W      ; expire
                                  1W )    ; negative caching TTL
   ;
          NS     blackhole.as112.arpa.
   ;
   ; There should be no other resource records included in this zone.
   ;
   ; Records that relate to RFC 1918-numbered resources within the
   ; site hosting this AS112 node should not be hosted on this
   ; name server.

   The "db.hostname.as112.net" and "db.hostname.as112.arpa" files
   follow, below.  These zones contain various resource records that
   provide operational data to users for troubleshooting or measurement
   purposes, and should be edited to suit local circumstances.  Note
   that the responses to the queries "HOSTNAME.AS112.NET IN TXT" and
   "HOSTNAME.AS112.ARPA IN TXT" should fit within a 512 octet DNS/UDP
   datagram: i.e. it should be available over UDP transport without
   requiring EDNS0 support.

   The optional LOC record [RFC1876] included in each zone apex provides
   information about the geospatial location of the node.














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   ; db.hostname.as112.net
   ;
   $TTL    1W
   @       SOA     server.example.net. admin.example.net. (
                           1               ; serial number
                           1W              ; refresh
                           1M              ; retry
                           1W              ; expire
                           1W )            ; negative caching TTL
   ;
           NS      blackhole-2.iana.org.
           NS      blackhole-1.iana.org.
   ;
           TXT     "Name of Facility or similar" "City, Country"
           TXT     "See http://www.as112.net/ for more information."
   ;
           LOC     45 25 0.000 N 75 42 0.000 W 80.00m 1m 10000m 10m


   ; db.hostname.as112.arpa
   ;
   $TTL    1W
   @       SOA     server.example.net. admin.example.net. (
                           1               ; serial number
                           1W              ; refresh
                           1M              ; retry
                           1W              ; expire
                           1W )            ; negative caching TTL
   ;
           NS      blackhole.as112.arpa.
   ;
           TXT     "Name of Facility or similar" "City, Country"
           TXT     "See http://www.as112.net/ for more information."
   ;
           LOC     45 25 0.000 N 75 42 0.000 W 80.00m 1m 10000m 10m

3.6.  Testing a Newly-Installed Node

   The BIND9 tool "dig" can be used to retrieve the TXT resource records
   associated with the names "HOSTNAME.AS112.NET" and
   "HOSTNAME.AS112.ARPA", directed at one of the AS112 anycast name
   server addresses.  Continuing the example from above, the response
   received should indicate the identity of the AS112 node that
   responded to the query.  See Section 3.5 for more details about the
   resource records associated with "HOSTNAME.AS112.NET".






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       % dig @prisoner.iana.org hostname.as112.net txt +short +norec
       "Name of Facility or similar" "City, Country"
       "See http://www.as112.net/ for more information."
       %

   If the response received indicates a different node is being used,
   then there is probably a routing problem to solve.  If there is no
   response received at all, there might be host or name server problem.
   Judicious use of tools such as traceroute, and consultation of BGP
   looking glasses might be useful in troubleshooting.

   Note that an appropriate set of tests for a new server will include
   queries sent from many different places within the expected service
   area of the node, using both UDP and TCP transport, and exercising
   all three AS112 anycast name server addresses.




































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4.  Operations

4.1.  Monitoring

   AS112 nodes should be monitored to ensure they are functioning
   correctly, just as with any other production service.  An AS112 node
   that stops answering queries correctly can cause failures and
   timeouts in unexpected places and can lead to failures in dependent
   systems that can be difficult to troubleshoot.

4.2.  Downtime

   An AS112 node that needs to go off-line (e.g. for planned maintenance
   or as part of the diagnosis of some problem) should stop advertising
   the AS112 service prefix to its BGP peers.  This can be done by
   shutting down the routing software on the node altogether or by
   causing the routing system to withdraw the route.

   Withdrawing the service prefix is important in order to avoid
   blackholing query traffic in the event that the DNS software on the
   node is not functioning normally.

4.3.  Statistics and Measurement

   Use of the AS112 node should be measured in order to track long-term
   trends, identify anomalous conditions, and to ensure that the
   configuration of the AS112 node is sufficient to handle the query
   load.

   Examples of free monitoring tools that might be useful to operators
   of AS112 nodes include:

   o  bindgraph [3]

   o  dnstop [4]

   o  DSC [5]














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5.  Communications

   It is good operational practice to notify the community of users that
   may fall within the reach of a new AS112 node before it is installed.
   At Internet Exchanges, local mailing lists usually exist to
   facilitate such announcements.

   For nodes that are intended to be globally reachable, coordination
   with other AS112 operators is especially recommended.  The mailing
   list <mailto:as112-ops@lists.dns-oarc.net> is operated for this
   purpose.

   Information pertinent to AS112 operations is maintained at
   <http://www.as112.net/>.

   Information about an AS112 node should also be published within the
   DNS, within the "HOSTNAME.AS112.NET" and "HOSTNAME.AS112.ARPA" zones.
   See Section 3.5 for more details.

































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6.  On the Future of AS112 Nodes

   It is recommended practice for the operators of recursive name
   servers to answer queries for zones served by AS112 nodes locally,
   such that queries never have an opportunity to reach AS112 servers
   [RFC6303].  Operational experience with AS112 nodes does not
   currently indicate an observable trend towards compliance with those
   recommendations, however.

   It is expected that some DNS software vendors will include default
   configuration that will implement measures such as those described in
   [RFC6303].  If such software is widely deployed, it is reasonable to
   assume that the query load received by AS112 nodes will decrease;
   however, it is safe to assume that the query load will not decrease
   to zero, and consequently that AS112 nodes will continue to provide a
   useful service for the foreseeable future.

   The use of DNAME Redirection to provide AS112 service is new, and
   hence is informed by minimal operational experience.  The use of
   DNAME means that queries for many source zones could be redirected to
   AS112 infrastructure with no real opportunity for coordination.

   If successful, and in the absence of operational concerns, the
   community might well recommend the retirement of the original Direct
   Delegation AS112 service, with equivalent service for the zones
   concerned instead provided using DNAME Redirection.  This document
   makes no such recommendation, however.
























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7.  IANA Considerations

   The name servers associated with Direct Delegation AS112 service are
   all named under the domain IANA.ORG (see Section 2.3).  However, the
   anycast infrastructure itself is operated by a loosely-coordinated,
   diverse mix of organisations across the Internet, and is not an IANA
   function.

   The autonomous system number 112 and the IPv4 prefix 192.175.48.0/24
   were assigned by ARIN.

   The IPv4 prefix TBA and the IPv6 prefix TBA, used for DNAME
   Redirection AS112 service, were assigned by the IANA
   [I-D.ietf-dnsop-as112-dname].

   This document has no IANA actions.



































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8.  Security Considerations

   Hosts should never normally send queries to AS112 servers; queries
   relating to private-use addresses should be answered locally within a
   site.  Hosts that send queries to AS112 servers may well leak
   information relating to private infrastructure to the public network,
   and this could present a security risk.  This risk is orthogonal to
   the presence or absence of authoritative servers for these zones in
   the public DNS infrastructure, however.

   Queries that are answered by AS112 servers are usually unintentional;
   it follows that the responses from AS112 servers are usually
   unexpected.  Unexpected inbound traffic can trigger intrusion
   detection systems or alerts by firewalls.  Operators of AS112 servers
   should be prepared to be contacted by operators of remote
   infrastructure who believe their security has been violated.  Advice
   to those who mistakenly believe that responses from AS112 nodes
   constitutes an attack on their infrastructure can be found in
   [RFC6305].

   The deployment of AS112 nodes is very loosely coordinated compared to
   other services distributed using anycast.  The malicious compromise
   of an AS112 node and subversion of the data served by the node is
   hence more difficult to detect due to the lack of central management.
   Since it is conceivable that changing the responses to queries
   received by AS112 nodes might influence the behaviour of the hosts
   sending the queries, such a compromise might be used as an attack
   vector against private infrastructure.

   Operators of AS112 should take appropriate measures to ensure that
   AS112 nodes are appropriately protected from compromise, such as
   would normally be employed for production name server or network
   infrastructure.  The guidance provided for root name servers in
   [RFC2870] may be instructive.

   The zones hosted by AS112 servers are not signed with DNSSEC
   [RFC4033].  Given the distributed and loosely-coordinated structure
   of the AS112 service, the zones concerned could only be signed if the
   private key material used was effectively public, obviating any
   security benefit resulting from the use of those keys.











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9.  Acknowledgements

   The authors wish to acknowledge the assistance of Bill Manning, John
   Brown, Marco D'Itri, Daniele Arena, Stephane Bortzmeyer, Frank
   Habicht, Chris Thompson, Peter Losher, Peter Koch, Alfred Hoenes and
   S. Moonesamy in the preparation of [RFC6304], which this document
   supercedes.

   The authors further acknowledge the assistance of YOUR NAME HERE in
   the preparation of this document.









































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10.  References

10.1.  Normative References

   [I-D.ietf-dnsop-as112-dname]
              Abley, J., Dickson, B., Kumari, W., and G. Michaelson,
              "AS112 Redirection using DNAME",
              draft-ietf-dnsop-as112-dname-00 (work in progress),
              November 2013.

   [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
              STD 13, RFC 1034, November 1987.

   [RFC1918]  Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
              E. Lear, "Address Allocation for Private Internets",
              BCP 5, RFC 1918, February 1996.

   [RFC2870]  Bush, R., Karrenberg, D., Kosters, M., and R. Plzak, "Root
              Name Server Operational Requirements", BCP 40, RFC 2870,
              June 2000.

   [RFC4033]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "DNS Security Introduction and Requirements",
              RFC 4033, March 2005.

   [RFC4271]  Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
              Protocol 4 (BGP-4)", RFC 4271, January 2006.

   [RFC4786]  Abley, J. and K. Lindqvist, "Operation of Anycast
              Services", BCP 126, RFC 4786, December 2006.

10.2.  Informative References

   [RFC1876]  Davis, C., Vixie, P., Goodwin, T., and I. Dickinson, "A
              Means for Expressing Location Information in the Domain
              Name System", RFC 1876, January 1996.

   [RFC5735]  Cotton, M. and L. Vegoda, "Special Use IPv4 Addresses",
              RFC 5735, January 2010.

   [RFC5855]  Abley, J. and T. Manderson, "Nameservers for IPv4 and IPv6
              Reverse Zones", BCP 155, RFC 5855, May 2010.

   [RFC6303]  Andrews, M., "Locally Served DNS Zones", BCP 163,
              RFC 6303, July 2011.

   [RFC6304]  Abley, J. and W. Maton, "AS112 Nameserver Operations",
              RFC 6304, July 2011.



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   [RFC6305]  Abley, J. and W. Maton, "I'm Being Attacked by
              PRISONER.IANA.ORG!", RFC 6305, July 2011.

   [RFC6672]  Rose, S. and W. Wijngaards, "DNAME Redirection in the
              DNS", RFC 6672, June 2012.














































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URIs

   [1]  <http://www.quagga.net/>

   [2]  <http://www.isc.org/software/BIND/>

   [3]  <http://www.linux.it/~md/software/>

   [4]  <http://dns.measurement-factory.com/tools/dnstop/>

   [5]  <http://dns.measurement-factory.com/tools/dsc/>








































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Appendix A.  History

   Widespread use of the private address blocks listed in [RFC1918]
   followed that document's publication in 1996.  At that time the IN-
   ADDR.ARPA zone was served by root servers.

   The idea of off-loading IN-ADDR.ARPA queries relating to [RFC1918]
   addresses from the root name servers was first proposed by Bill
   Manning and John Brown.

   The use of anycast for distributing authoritative DNS service for
   [RFC1918] IN-ADDR.ARPA zones was subsequently proposed at a private
   meeting of root server operators.

   ARIN provided an IPv4 prefix for the anycast service and also the
   autonomous system number 112 for use in originating that prefix.
   This assignment gave the project its name.

   In 2002, the first AS112 anycast nodes were deployed.

   In 2011, the IN-ADDR.ARPA zone was redelegated from the root servers
   to a new set of servers operated independently by AfriNIC, APNIC,
   ARIN, ICANN, LACNIC, and the RIPE NCC and named according to
   [RFC5855].

   [RFC6304], the precursor to this document, was published in July
   2011.

   The use of anycast name servers in the AS112 project contributed to
   the operational experience of anycast DNS services, and it can be
   seen as a precursor to the anycast distribution of other
   authoritative DNS servers in subsequent years (e.g., various root
   servers).


















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Appendix B.  Revision History and Venue

   A suitable venue for discussion of this document is the dnsop working
   group.  Private comments may also be directed at the authors.

   This section (and sub-sections) should be removed prior to
   publication.

B.1.  draft-jabley-dnsop-rfc6304bis-00

   Initial revision of [RFC6304] intended to provide guidance consistent
   with [I-D.ietf-dnsop-as112-dname].







































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Authors' Addresses

   Joe Abley
   Dyn, Inc.
   470 Moore Street
   London, ON  N6C 2C2
   Canada

   Phone: +1 519 670 9327
   Email: jabley@dyn.com


   William F. Maton Sotomayor
   DNS Operations, Analysis and Research Centre

   Email: wfms@dns-oarc.net



































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