[Docs] [txt|pdf|xml] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03

Internet Engineering Task Force                             M. Sivaraman
Internet-Draft                                                 S. Morris
Intended status: Experimental                                  R. Bellis
Expires: July 10, 2017                                       W. Krecicki
                                             Internet Systems Consortium
                                                         January 6, 2017


                           DNS catalog zones
                 draft-muks-dnsop-dns-catalog-zones-02

Abstract

   This document describes a method for automatic zone catalog
   provisioning and synchronization among DNS primary and secondary
   nameservers by storing and transferring the catalogs as regular DNS
   zones.

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-
   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 July 10, 2017.

Copyright Notice

   Copyright (c) 2017 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




Sivaraman, et al.         Expires July 10, 2017                 [Page 1]


Internet-Draft              DNS catalog zones               January 2017


   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Catalog zones . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Description . . . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  Resource record fields  . . . . . . . . . . . . . . . . .   4
     2.3.  SOA and NS records at apex  . . . . . . . . . . . . . . .   4
     2.4.  Zone properties map and owner names . . . . . . . . . . .   5
     2.5.  Zone property value data types  . . . . . . . . . . . . .   6
       2.5.1.  Strings . . . . . . . . . . . . . . . . . . . . . . .   6
       2.5.2.  Booleans  . . . . . . . . . . . . . . . . . . . . . .   6
       2.5.3.  Integers  . . . . . . . . . . . . . . . . . . . . . .   6
       2.5.4.  Floating-point values . . . . . . . . . . . . . . . .   7
       2.5.5.  Single domain names . . . . . . . . . . . . . . . . .   7
       2.5.6.  Unordered list of domain names  . . . . . . . . . . .   8
       2.5.7.  List of network addresses . . . . . . . . . . . . . .   8
       2.5.8.  Single host address . . . . . . . . . . . . . . . . .   9
       2.5.9.  Comments  . . . . . . . . . . . . . . . . . . . . . .   9
     2.6.  Catalog zone schema version . . . . . . . . . . . . . . .   9
     2.7.  List of member zones  . . . . . . . . . . . . . . . . . .   9
     2.8.  Zone configuration properties . . . . . . . . . . . . . .  10
       2.8.1.  zone-soa-default-serial . . . . . . . . . . . . . . .  10
       2.8.2.  zone-soa-default-refresh  . . . . . . . . . . . . . .  10
     2.9.  Zone properties specific to a member zone . . . . . . . .  10
     2.10. Example of a catalog zone . . . . . . . . . . . . . . . .  11
   3.  Nameserver behavior and requirements  . . . . . . . . . . . .  11
     3.1.  General requirements  . . . . . . . . . . . . . . . . . .  11
     3.2.  Updating catalog zones  . . . . . . . . . . . . . . . . .  12
     3.3.  Implementation notes  . . . . . . . . . . . . . . . . . .  12
   4.  Security considerations . . . . . . . . . . . . . . . . . . .  13
   5.  IANA considerations . . . . . . . . . . . . . . . . . . . . .  13
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     7.1.  Normative references  . . . . . . . . . . . . . . . . . .  14
     7.2.  Informative references  . . . . . . . . . . . . . . . . .  15
   Appendix A.  Glossary . . . . . . . . . . . . . . . . . . . . . .  15
   Appendix B.  Open issues and discussion (to be removed before
                final publication) . . . . . . . . . . . . . . . . .  16
   Appendix C.  Change History (to be removed before final
                publication) . . . . . . . . . . . . . . . . . . . .  17
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  18







Sivaraman, et al.         Expires July 10, 2017                 [Page 2]


Internet-Draft              DNS catalog zones               January 2017


1.  Introduction

   DNS nameservers implement AXFR and IXFR for zone data synchronization
   among a zone's primary and secondary nameservers, but the list of
   zones served by the primary (called a catalog in [RFC1035]) is not
   automatically synchronized.  The administrator of a DNS nameserver
   farm has to synchronize such zone catalogs among primaries and their
   secondary nameservers manually or via an external application layer.
   This can be inconvenient, error-prone and dependent on the nameserver
   implementation.

   A method for automatic zone catalog provisioning and synchronization
   is useful, so that the zone catalog can be maintained in a reference
   location by an administrator, similar to zone data.

   This document describes one such method, in which the catalog is
   represented as a regular DNS zone called a "catalog zone", and
   transferred using DNS zone transfers.  The representation of catalogs
   within DNS zones is specified and nameserver requirements are listed
   so that DNS implementations can support catalog zones.

   The contents and representation of catalog zones are described in
   Section 2.  Nameserver behavior is described in Section 3.  A
   glossary of some terms used in this memo is provided in Appendix A.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

2.  Catalog zones

2.1.  Description

   A catalog zone is a specially crafted DNS zone that contains, as DNS
   zone data, a list of DNS zones called member zones, associated
   template zone configuration common to all its member zones, and zone-
   specific configuration that applies to a respective zone.  An
   implementation of catalog zones MAY allow catalog zones to include
   other catalog zones, but template zone configuration present in a
   catalog zone only applies to its immediate member zones.  A catalog
   zone is meant to be used to provision DNS catalogs to secondary
   nameservers via zone transfers, for the purpose of setting up member
   zones to be served from these secondary nameservers.

   A catalog zone uses some RR TYPEs such as PTR with alternate
   semantics for its purposes.  Although this may be controversial, the
   situation is similar to other similar zone-based representations such
   as response-policy zones [RPZ].  A design criterion of catalog zones



Sivaraman, et al.         Expires July 10, 2017                 [Page 3]


Internet-Draft              DNS catalog zones               January 2017


   is that none of the RR TYPEs used therein may incur any additional
   section processing during DNS QUERY.

   Member zones' configuration is specified as a map of zone properties,
   represented as a subtree of a node [RFC1034] in the domain name space
   inside a catalog zone.  This is described in Section 2.4.  Each zone
   property has a name and an associated value of a specific data type.
   Zone property value data types are described in Section 2.5.  A list
   of permitted zone property names and their data types is given in
   Section 2.8.

   TBD: Transitive catalogs

2.2.  Resource record fields

   A catalog zone contains various resource records (RRs).  They have
   NAME, TYPE, CLASS, TTL, RDLENGTH and RDATA as fields [RFC1035].

   The NAME field contains the owner name of the respective RR.  As with
   all DNS zones, the owner name must be a child of the catalog zone
   name.

   The TYPE field depends on the type of catalog zone property value
   being represented.  Section 2.5 describes how various zone property
   value types are represented.

   The CLASS field of the RR MUST be set to IN(1) [RFC1035].  This is
   because some RR TYPEs such as APL used by catalog zones are defined
   only for the IN CLASS.

   The TTL field's value is not specially defined by this memo.  Catalog
   zones are for nameserver management only and are not intended for
   general querying.  Operators should use whatever value seems
   convenient for any management applications that may query the catalog
   zone.

   The RDLENGTH field contains the length of the RDATA field.

   The content of the RDATA field depends on the type of catalog zone
   property value being represented.  Section 2.5 describes how various
   zone property value types are represented.

2.3.  SOA and NS records at apex

   Similar to any other DNS zone, a catalog zone would be expected to
   have a syntactically correct SOA record and one or more NS records at
   its apex.




Sivaraman, et al.         Expires July 10, 2017                 [Page 4]


Internet-Draft              DNS catalog zones               January 2017


   The SOA record's SERIAL, REFRESH, RETRY and EXPIRE fields [RFC1035]
   are used during zone transfer.  A catalog zone's SOA SERIAL field
   SHOULD increase when an update is made to the catalog zone's contents
   as per serial number arithmetic defined in [RFC1982].  Otherwise,
   secondary nameservers may not notice updates to the catalog zone's
   contents.

   The SOA record's MINIMUM field's value is not specially defined by
   this memo.  Although they are regular DNS zones, catalog zones
   contain only information for the management of a set of nameservers.
   For this reason, operators may want to limit the systems able to
   query these zones.

   As catalog zones do not participate in the DNS, NS records at the
   apex are not used but they are still required so that catalog zones
   are syntactically correct DNS zones.  No parent delegation for the
   catalog zone is required.  Any valid DNS name can be used in the
   NSDNAME field of such NS records [RFC1035] and they MUST be ignored.
   A single NS RR with an NSDNAME field containing the absolute name
   "invalid." is recommended [RFC2606].

2.4.  Zone properties map and owner names

   Member zones' configuration is specified as a map of zone properties,
   represented as a subtree of a node [RFC1034] in the domain name space
   inside a catalog zone.  A subtree of child nodes is used for a nested
   map, occuping another label level.  A map element's key (property
   name) is represented in the label at that level.  For example, if a
   catalog zone is named "catalog1.example.org." and contains a property
   with name "prop0", the corresponding owner name of the node
   representing that property is "prop0.catalog1.example.org."

   Zone property names are case-insensitive.  Each zone property may use
   only one data type for its values.  A list of permitted zone property
   names and their data types is given in Section 2.8.

   Many properties are single-valued, but some properties can be
   collections with thousands of values.  An example is the list of
   member zones within a catalog zone, which can be larger than any
   single RDATA instance can allow.  Multiple RRs are used to represent
   such properties.

   TBD: Currently a hashing method in owner names is used to split the
   elements of such properties with multiple RRs into individual RRsets,
   one per RR.  This needs to be revisited as IXFR and DNS UPDATE both
   allow individual RRs within an RRset to be modified.  The hashing
   method used is described in the appropriate property value data types
   in Section 2.5.



Sivaraman, et al.         Expires July 10, 2017                 [Page 5]


Internet-Draft              DNS catalog zones               January 2017


2.5.  Zone property value data types

2.5.1.  Strings

   A property with a string value is specified using a single TXT RR
   [RFC1035] with owner name set to the name of the property as a sub-
   domain of the catalog zone name, and RDATA set to the property value.

   For example, if a catalog zone is named "catalog1.example.org." and
   contains a property "prop0" with string value "Example", the
   corresponding RR would appear as follows:

           prop0.catalog1.example.org. 3600 IN TXT "Example"

   Here, "prop0" can contain multiple TXT RRs at that node of the domain
   name space [RFC1034].  The single string property SHOULD be checked
   by the implementation.

2.5.2.  Booleans

   A property with a boolean value is specified using a single TXT RR
   with owner name set to the name of the property as a sub-domain of
   the catalog zone name, and RDATA set to "true" for true condition and
   "false" for false condition.  The RDATA is case-insensitive.

   For example, if a catalog zone is named "catalog1.example.org." and
   contains a property "active" with boolean value false, the
   corresponding RR would appear as follows:

           active.catalog1.example.org. 3600 IN TXT "false"

   Here, "active" can contain multiple TXT RRs at that node of the
   domain name space [RFC1034].  The single boolean property SHOULD be
   checked by the implementation.

2.5.3.  Integers

   A property with an integer value is specified using a single TXT RR
   for signed integers or unsigned integers, with owner name set to the
   name of the property as a sub-domain of the catalog zone name, and
   RDATA set to the property value.

   A signed integer's TXT RDATA uses the representation of an unsuffixed
   "integer constant" as defined in the C programming language standard
   [ISO.9899.1990] (of the type matching a 64-bit signed integer on that
   platform), with an optional minus prefix.  The representation MUST be
   specified using a single <character-string> [RFC1034].




Sivaraman, et al.         Expires July 10, 2017                 [Page 6]


Internet-Draft              DNS catalog zones               January 2017


   An unsigned integer's TXT RDATA uses the representation of an
   unsuffixed "integer constant" as defined in the C programming
   language standard [ISO.9899.1990] (of the type matching a 64-bit
   unsigned integer on that platform).  The representation MUST be
   specified using a single <character-string> [RFC1034].

   For example, if a catalog zone is named "catalog1.example.org." and
   contains a property "min-ttl" with unsigned integer value 300, the
   corresponding RR would appear as follows:

           min-ttl.catalog1.example.org. 3600 IN TXT "300"

   Here, "min-ttl" can contain multiple TXT RRs at that node of the
   domain name space [RFC1034].  The single integer property SHOULD be
   checked by the implementation.

2.5.4.  Floating-point values

   A property with a floating-point value is specified using a single
   TXT RR with owner name set to the name of the property as a sub-
   domain of the catalog zone name, and RDATA set to the property value.

   A floating-point value's TXT RDATA uses the representation of an
   unsuffixed "floating constant" as defined in the C programming
   language standard [ISO.9899.1990].  The representation MUST be
   specified using a single <character-string> [RFC1034].

   For example, if a catalog zone is named "catalog1.example.org." and
   contains a property "decay-rate" with value 0.15, the corresponding
   RR may appear as follows:

           decay-rate.catalog1.example.org. 3600 IN TXT "15e-2"

   Here, "decay-rate" can contain multiple TXT RRs at that node of the
   domain name space [RFC1034].  The single floating-point property
   SHOULD be checked by the implementation.

2.5.5.  Single domain names

   A property with a single domain name as value is specified using a
   PTR RR [RFC1035] with owner name set to the name of the property as a
   sub-domain of the catalog zone name, and RDATA set to the property
   value.

   For example, if a catalog zone is named "catalog1.example.org." and
   contains a property "prop1" with value "val1.example.com.", the
   corresponding RR would appear as follows:




Sivaraman, et al.         Expires July 10, 2017                 [Page 7]


Internet-Draft              DNS catalog zones               January 2017


           prop1.catalog1.example.org. 3600 IN PTR val1.example.com.

   Here, "prop1" can contain multiple PTR RRs at that node of the domain
   name space [RFC1034].  The single domain name property SHOULD be
   checked by the implementation.

2.5.6.  Unordered list of domain names

   Let N be an absolute name formed by concatenating the RDATA hash (see
   Appendix A), the name of the property, and the catalog zone name in
   that order, such that N is a unique owner name in the catalog zone.

   Then, a property containing an unordered list of domain names as
   value is specified using multiple PTR RRs [RFC1035] with owner name
   set to N, and each RR's RDATA set to each domain name in the list of
   the property's value respectively.

   For example, if a catalog zone is named "catalog1.example.org." and
   contains a property "prop2" with its value being an unordered list of
   two names "a.example.com." and "b.example.com.", the corresponding
   RRs would appear as follows:

          <hash1>.prop2.catalog1.example.org. 3600 IN PTR a.example.com.
          <hash2>.prop2.catalog1.example.org. 3600 IN PTR b.example.com.

   Here, "prop2"'s subtree child nodes (in the domain name space
   [RFC1034]) can contain multiple PTR RRs at each child.  For example,
   <hash1>.prop2 may contain multiple PTR RRs at that node.  The single
   domain name property SHOULD be checked by the implementation.

2.5.7.  List of network addresses

   A property with a list of network addresses as value is specified
   using a single APL RR [RFC3123] with owner name set to the name of
   the property as a sub-domain of the catalog zone name, and RDATA set
   to the property value.  In its presentation format, the "!" character
   (corresponding to the negation flag) is used to negate a network
   element.  The exact meaning of a negated network element is left to
   be described by the property that APL is used for.  Note that the APL
   RR TYPE is defined only for the IN(1) RR CLASS.

   For example, if a catalog zone is named "catalog1.example.org." and
   contains a property "allow-query" with value [192.0.2.0/24,
   2001:db8::/32] as the list of networks, the corresponding RR would
   appear as follows:

           allow-query.catalog1.example.org. 3600 IN APL (
                   1:192.0.2.0/24 2:2001:db8::/32)



Sivaraman, et al.         Expires July 10, 2017                 [Page 8]


Internet-Draft              DNS catalog zones               January 2017


   Here, "allow-query" can contain multiple APL RRs at that node of the
   domain name space [RFC1034].  The single APL RR property SHOULD be
   checked by the implementation.

2.5.8.  Single host address

   A single host address is represented using the list of network
   addresses data type (see Section 2.5.7) with a suitable network and
   prefix to result in a single host address.

2.5.9.  Comments

   Comments may be added anywhere in a catalog zone using a scheme such
   as NOTE RRs [I-D.hunt-note-rr].  This memo does not depend on NOTE
   RRs and it is only suggested here as an informative reference.

2.6.  Catalog zone schema version

   The catalog zone schema version is specified by an unsigned integer
   property with the property name "version".  All catalog zones MUST
   have this property present.  Primary and secondary nameservers MUST
   NOT use catalog zones with an unexpected value in this property, but
   they may be transferred as ordinary zones.  For this memo, the
   "version" property value MUST be set to 1.

   For example, if a catalog zone is named "catalog1.example.org.", the
   corresponding RR MUST look as follows:

           version.catalog1.example.org. 3600 IN TXT "1"

   Here, "version" can contain multiple TXT RRs at that node of the
   domain name space [RFC1034].  The single TXT RR property SHOULD be
   checked by the implementation.

2.7.  List of member zones

   The list of member zones are specified as an unordered list (see
   Section 2.5.6) of domain names under the owner name "zones" where
   "zones" is a sub-domain of the catalog zone.

   The names of member zones are represented on the RDATA side instead
   of as part of owner names so that all valid domain names may be
   represented regardless of their length.  [RFC1035]

   For example, if a catalog zone is named "catalog1.example.org." and
   lists 3 zones "example.com.", "example.net." and "example.org.", the
   RRs would appear as follows:




Sivaraman, et al.         Expires July 10, 2017                 [Page 9]


Internet-Draft              DNS catalog zones               January 2017


           <hash>.zones.catalog1.example.org. 3600 IN PTR example.com.
           <hash>.zones.catalog1.example.org. 3600 IN PTR example.net.
           <hash>.zones.catalog1.example.org. 3600 IN PTR example.org.

2.8.  Zone configuration properties

   TBD: Prepare a list of zone configuration properties that are common
   to DNS implementations.  This is so that a company may manage a
   catalog zone using a Windows DNS server as the primary, and a
   secondary nameserver hosting service may pick up the common
   properties and may use a different nameserver implementation such as
   BIND or NSD on a POSIX operating system to serve it.

   TBD: We may specify that unrecognized zone property names must be
   ignored, or that nameserver specific properties must be specified
   using the "x-" prefix similar to MIME type naming.

   TBD: Any list of zone properties is ideally maintained as a registry
   rather than within this memo.

2.8.1.  zone-soa-default-serial

   TBD.

2.8.2.  zone-soa-default-refresh

   TBD.

2.9.  Zone properties specific to a member zone

   Member zones in a catalog zone share template zone configuration that
   is common to all member zones in that catalog.  This section
   describes the syntax that can be used to specify zone properties
   specific to single member zones.

   Let N be an absolute name formed by concatenating the member zone
   name hash as a label (see Appendix A), the label "zones", and the
   catalog zone name in that order, such that N is a unique owner name
   in the catalog zone.

   Zone properties specific to a particular member zone are specified
   under the respective sub-domain N.

   For example, if a catalog zone is named "catalog1.example.org." and a
   member zone "example.com." contains a property "prop0" with string
   (see Section 2.5.1) value "Example", the corresponding RR would
   appear as follows:




Sivaraman, et al.         Expires July 10, 2017                [Page 10]


Internet-Draft              DNS catalog zones               January 2017


        prop0.<m-hash>.zones.catalog1.example.org. 3600 IN TXT "Example"

   As another example, if a catalog zone is named "cat1.example.org."
   and a member zone "example.com." contains a property "prop2" with its
   value being an unordered list (see Section 2.5.6) of two domain names
   "a.example.com." and "b.example.com.", the corresponding RRs would
   appear as follows:

           (<hash>.prop2.<m-hash>.zones.cat1.example.org.
            3600 IN PTR a.example.com.)
           (<hash>.prop2.<m-hash>.zones.cat1.example.org.
            3600 IN PTR b.example.com.)

2.10.  Example of a catalog zone

               $ORIGIN catalog.example.org.
               @           IN SOA  . . 1 3600 3600 86400 3600
                           IN NS   invalid.
               version     IN TXT  "1"
               (5960775ba382e7a4e09263fc06e7c00569b6a05c.zones
                IN PTR domain1.example.com.)

3.  Nameserver behavior and requirements

3.1.  General requirements

   TBD: Explain nameserver behavior in a more detailed way here.  It is
   under-specified.

   As it is a regular DNS zone, a catalog zone can be transferred using
   DNS zone transfers among nameservers.

   Although they are regular DNS zones, catalog zones contain only
   information for the management of a set of nameservers.  For this
   reason, operators may want to limit the systems able to query these
   zones.  It may be inconvenient to serve some contents of catalog
   zones via DNS queries anyway due to the nature of their
   representation.  A separate method of querying entries inside the
   catalog zone may be made available by nameserver implementations (see
   Section 3.3).

   Catalog updates should be automatic, i.e., when a nameserver that
   supports catalog zones completes a zone transfer for a catalog zone,
   it SHOULD apply changes to the catalog within the running nameserver
   automatically without any manual intervention.

   As with regular zones, primary and secondary nameservers for a
   catalog zone may be operated by different administrators.  The



Sivaraman, et al.         Expires July 10, 2017                [Page 11]


Internet-Draft              DNS catalog zones               January 2017


   secondary nameservers may be configured to synchronize catalog zones
   from the primary, but the primary's administrators may not have any
   administrative access to the secondaries.

   A catalog zone can be updated via DNS UPDATE on a reference primary
   nameserver, or via zone transfers.  Nameservers MAY allow loading and
   transfer of broken zones with incorrect catalog zone syntax (as they
   are treated as regular zones), but nameservers MUST NOT process such
   broken zones as catalog zones.  For the purpose of catalog
   processing, the broken catalogs MUST be ignored.  If a broken catalog
   zone was transferred, the newly transferred catalog zone MUST be
   ignored (but the older copy of the catalog zone SHOULD be left
   running subject to values in SOA fields).

   If there is a clash between an existing member zone's name and an
   incoming member zone's name (via transfer or update), the new
   instance of the zone MUST be ignored and an error SHOULD be logged.

   When zones are introduced into a catalog zone, a primary SHOULD first
   make the new zones available for transfers before making the updated
   catalog zone available for transfer, or sending NOTIFY for the
   catalog zone to secondaries.  Note that secondary nameservers may
   attempt to transfer the catalog zone upon refresh timeout, so care
   must be taken to make the member zones available before any update to
   the list of member zones is visible in the catalog zone.

   When zones are deleted from a catalog zone, a primary MAY delete the
   member zone immediately after notifying secondaries.  It is up to the
   secondary nameserver to handle this condition correctly.

   TBD: Transitive primary-secondary relationships

3.2.  Updating catalog zones

   TBD: Explain updating catalog zones using DNS UPDATE.

3.3.  Implementation notes

   Catalog zones on secondary nameservers would have to be setup
   manually, perhaps as static configuration, similar to how ordinary
   DNS zones are configured.  Members of such catalog zones will be
   automatically synchronized by the secondary after the catalog zone is
   configured.

   An administrator would want to look at data inside a catalog zone.
   Typical queries may include dumping the list of member zones, dumping
   a member zone's effective configuration, querying a specific property
   value of a member zone, etc.  Because of the syntax of catalog zones,



Sivaraman, et al.         Expires July 10, 2017                [Page 12]


Internet-Draft              DNS catalog zones               January 2017


   it may not be possible to perform these queries intuitively, or in
   some cases, at all, using DNS QUERY.  The list of member zones may
   not fit in a single DNS message.  The set of present properties for a
   zone cannot be queried using a single DNS QUERY.

   Implementations are advised to provide a tool that uses either the
   output of AXFR or an out-of-band method to perform queries on catalog
   zones.

4.  Security considerations

   As catalog zones are transmitted using DNS zone transfers, it is
   absolutely essential for these transfers to be protected from
   unexpected modifications on the route.  So, catalog zone transfers
   SHOULD be authenticated using TSIG [RFC2845].  A primary nameserver
   SHOULD NOT serve a catalog zone for transfer without using TSIG and a
   secondary nameserver SHOULD abandon an update to a catalog zone that
   was received without using TSIG.

   DNS UPDATE [RFC2136] to catalog zones similarly SHOULD be
   authenticated using TSIG.

   Zone transfers of member zones SHOULD similarly be authenticated
   using TSIG [RFC2845].  The TSIG shared secrets used for member zones
   MUST NOT be mentioned anywhere in the catalog zone data.  However,
   key identifiers may be shared within catalog zones.

   Catalog zones do not need to be signed using DNSSEC; their zone
   transfers being authenticated by TSIG.  Signed zones MUST be handled
   normally by nameservers, and their contents MUST NOT be DNSSEC-
   validated.

5.  IANA considerations

   This document has no IANA actions.

6.  Acknowledgements

   Catalog zones originated as the chosen method among various proposals
   that were evaluated at ISC for easy zone management.  The chosen
   method of storing the catalog as a regular DNS zone was proposed by
   Stephen Morris.

   We later discovered that Paul Vixie's earlier [Metazones] proposal
   implemented a similar approach and reviewed it.  Catalog zones
   borrows some syntax ideas from Metazones, as both share this scheme
   of representing the catalog as a regular DNS zone.




Sivaraman, et al.         Expires July 10, 2017                [Page 13]


Internet-Draft              DNS catalog zones               January 2017


   Thanks to Brian Conry, Evan Hunt, and Victoria Risk for reviewing
   draft proposals and providing support, comments and suggestions.
   Thanks to Tony Finch and Patrik Lundin for reviewing the draft and
   providing comments.

   Thanks to BIND users who reviewed draft proposals and offered
   comments and suggestions.

7.  References

7.1.  Normative references

   [FIPS.180-4.2015]
              National Institute of Standards and Technology, "Secure
              Hash Standard", FIPS PUB 180-4, August 2015,
              <http://csrc.nist.gov/publications/fips/fips180-4/
              fips-180-4.pdf>.

   [ISO.9899.1990]
              International Organization for Standardization,
              "Programming languages - C", ISO Standard 9899, 1990.

   [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
              STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
              <http://www.rfc-editor.org/info/rfc1034>.

   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
              November 1987, <http://www.rfc-editor.org/info/rfc1035>.

   [RFC1982]  Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982,
              DOI 10.17487/RFC1982, August 1996,
              <http://www.rfc-editor.org/info/rfc1982>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC2136]  Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound,
              "Dynamic Updates in the Domain Name System (DNS UPDATE)",
              RFC 2136, DOI 10.17487/RFC2136, April 1997,
              <http://www.rfc-editor.org/info/rfc2136>.

   [RFC2606]  Eastlake 3rd, D. and A. Panitz, "Reserved Top Level DNS
              Names", BCP 32, RFC 2606, DOI 10.17487/RFC2606, June 1999,
              <http://www.rfc-editor.org/info/rfc2606>.




Sivaraman, et al.         Expires July 10, 2017                [Page 14]


Internet-Draft              DNS catalog zones               January 2017


   [RFC2845]  Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B.
              Wellington, "Secret Key Transaction Authentication for DNS
              (TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000,
              <http://www.rfc-editor.org/info/rfc2845>.

   [RFC3123]  Koch, P., "A DNS RR Type for Lists of Address Prefixes
              (APL RR)", RFC 3123, DOI 10.17487/RFC3123, June 2001,
              <http://www.rfc-editor.org/info/rfc3123>.

   [RFC7719]  Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
              Terminology", RFC 7719, DOI 10.17487/RFC7719, December
              2015, <http://www.rfc-editor.org/info/rfc7719>.

7.2.  Informative references

   [I-D.hunt-note-rr]
              Hunt, E. and D. Mahoney, "A DNS Resource Record for
              Confidential Comments (NOTE RR)", draft-hunt-note-rr-01
              (work in progress), May 2014.

   [Metazones]
              Vixie, P., "Federated Domain Name Service Using DNS
              Metazones", 2005, <http://ss.vix.su/~vixie/mz.pdf>.

   [RPZ]      Vixie, P. and V. Schryver, "DNS Response Policy Zones (DNS
              RPZ)", 2010,
              <http://ftp.isc.org/isc/dnsrpz/isc-tn-2010-1.txt>.

Appendix A.  Glossary

   Catalog zone:  A DNS zone containing a DNS catalog, that is, a list
         of DNS zones and associated template zone configuration common
         to all member zones.

   Member zone:  A DNS zone whose configuration is published inside a
         catalog zone.

   Primary nameserver:  An authoritative server configured to be the
         source of zone transfer to one or more [secondary] nameservers.
         Also see [RFC7719].

   RDATA hash:  The hexadecimal format 40-digit SHA-1 [FIPS.180-4.2015]
         digest, of the RDATA of the corresponding RR.  For RDATA
         containing DNS names, no name compression must be in use, i.e.,
         the name must be in its full expanded wire data format when it
         is hashed.





Sivaraman, et al.         Expires July 10, 2017                [Page 15]


Internet-Draft              DNS catalog zones               January 2017


   Member zone name hash:  The hexadecimal format 40-digit SHA-1
         [FIPS.180-4.2015] digest, of a zone name in uncompressed wire
         format.

   Secondary nameserver:  An authoritative server which uses zone
         transfer to retrieve the zone.  Also see [RFC7719].

   Zone property:  A configuration parameter of a zone, sometimes also
         called a zone option.

Appendix B.  Open issues and discussion (to be removed before final
             publication)

   1.  Config options

       We want catalog zones to be adopted by multiple DNS
       implementations.  Towards this, we have to generalize zone config
       options and adopt a minimal set that we can expect most
       implementations to support.

   2.  Catalog zone and member zones on different primary nameservers

       Will it be possible to setup a catalog zone on one nameserver as
       primary, and allow its member zones to be served by different
       primary namesservers?

   3.  Transitive relationships

       For a catalog zone, a secondary nameserver may be a primary
       nameserver to a different set of nameservers in a nameserver
       farm.  In these transitive relationships, zone configuration
       options (such as also-notify and allow-transfer) may differ based
       on the location of the primary in the hierarchy.  It may not be
       possible to specify this within a catalog zone.

   4.  Templates

       Are support for config and zone data templates useful at this
       level?  They would add complexity across implementations.  If
       added, it would be better to restrict templates at the primary
       nameserver and let the secondary receive regular expanded zones.

   5.  Overriding controls

       A way to override zone config options (as prescribed by the
       catalog zones) on secondary nameservers was requested.  As this
       would be configured outside catalog zones, it may be better to
       leave this to implementations.



Sivaraman, et al.         Expires July 10, 2017                [Page 16]


Internet-Draft              DNS catalog zones               January 2017


   6.  Use of hashing

       Should use of hashing be completely removed, and replaced with
       the same common owner name for all property RRs in a collection?
       Both IXFR and DNS UPDATE allow changing individual RRs in a
       RRset.

   7.  Choice of hash function

       Should a different faster hash function be chosen to replace
       SHA-1 when computing catalog member zone name hashes?

   8.  Overriding existing RR types

       This memo currently overrides only the PTR RR TYPE's meaning as
       PTR is currently used for reverse lookups.  But such overridden
       use seems like a non-issue as PTR is defined to be a pointer to
       any name in [RFC1035].

   9.  APL limits

       APL can only support as many networks as can fit in its RDATA.
       Though a very large number of networks can be listed in a single
       RDATA field, it is still limited in size.  Will this limitation
       become a problem for any users?

Appendix C.  Change History (to be removed before final publication)

   o  draft-muks-dnsop-dns-catalog-zones-00
      Initial public draft.

   o  draft-muks-dnsop-dns-catalog-zones-01
      Added Witold, Ray as authors.  Fixed typos, consistency issues.
      Fixed references.  Updated Area.  Removed newly introduced custom
      RR TYPEs.  Changed schema version to 1.  Changed TSIG requirement
      from MUST to SHOULD.  Removed restrictive language about use of
      DNS QUERY.  When zones are introduced into a catalog zone, a
      primary SHOULD first make the new zones available for transfers
      first (instead of MUST).  Updated examples, esp. use IPv6 in
      examples per Fred Baker.  Add catalog zone example.

   o  draft-muks-dnsop-dns-catalog-zones-02
      Addressed some review comments by Patrik Lundin.








Sivaraman, et al.         Expires July 10, 2017                [Page 17]


Internet-Draft              DNS catalog zones               January 2017


Authors' Addresses

   Mukund Sivaraman
   Internet Systems Consortium
   950 Charter Street
   Redwood City, CA  94063
   US

   Email: muks@mukund.org
   URI:   http://www.isc.org/


   Stephen Morris
   Internet Systems Consortium
   950 Charter Street
   Redwood City, CA  94063
   US

   Email: stephen@isc.org
   URI:   http://www.isc.org/


   Ray Bellis
   Internet Systems Consortium
   950 Charter Street
   Redwood City, CA  94063
   US

   Email: ray@isc.org
   URI:   http://www.isc.org/


   Witold Krecicki
   Internet Systems Consortium
   950 Charter Street
   Redwood City, CA  94063
   US

   Email: wpk@isc.org
   URI:   http://www.isc.org/











Sivaraman, et al.         Expires July 10, 2017                [Page 18]


Html markup produced by rfcmarkup 1.124, available from https://tools.ietf.org/tools/rfcmarkup/