Internet Engineering Task Force S. Morris
Internet-Draft M. Sivaraman
Intended status: Experimental Internet Systems Consortium
Expires: April 20, 2016 October 18, 2015
DNS catalog zones
draft-muks-dnsop-dns-catalog-zones-00
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
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This Internet-Draft will expire on April 20, 2016.
Copyright Notice
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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 . . . . . . . . . . . . . . . 5
2.4. RR TYPEs to represent data . . . . . . . . . . . . . . . 5
2.4.1. BOOL RR TYPE (boolean condition) . . . . . . . . . . 5
2.4.1.1. BOOL RDATA wire format . . . . . . . . . . . . . 5
2.4.1.2. BOOL RDATA presentation format . . . . . . . . . 6
2.4.1.3. BOOL RR example . . . . . . . . . . . . . . . . . 6
2.4.2. FLOAT RR TYPE (floating-point value) . . . . . . . . 6
2.4.2.1. FLOAT RDATA wire format . . . . . . . . . . . . . 6
2.4.2.2. FLOAT RDATA presentation format . . . . . . . . . 6
2.4.2.3. FLOAT RR example . . . . . . . . . . . . . . . . 6
2.4.3. INT RR TYPE (64-bit signed integer value) . . . . . . 6
2.4.3.1. INT RDATA wire format . . . . . . . . . . . . . . 6
2.4.3.2. INT RDATA presentation format . . . . . . . . . . 7
2.4.3.3. INT RR example . . . . . . . . . . . . . . . . . 7
2.4.4. UINT RR TYPE (64-bit unsigned integer value) . . . . 7
2.4.4.1. UINT RDATA wire format . . . . . . . . . . . . . 7
2.4.4.2. UINT RDATA presentation format . . . . . . . . . 7
2.4.4.3. UINT RR example . . . . . . . . . . . . . . . . . 7
2.5. Zone properties map and owner names . . . . . . . . . . . 7
2.6. Zone property value data types . . . . . . . . . . . . . 8
2.6.1. Strings . . . . . . . . . . . . . . . . . . . . . . . 8
2.6.2. Booleans . . . . . . . . . . . . . . . . . . . . . . 8
2.6.3. Integers . . . . . . . . . . . . . . . . . . . . . . 9
2.6.4. Floating-point values . . . . . . . . . . . . . . . . 9
2.6.5. Single names . . . . . . . . . . . . . . . . . . . . 10
2.6.6. Unordered list of names . . . . . . . . . . . . . . . 10
2.6.7. List of network addresses . . . . . . . . . . . . . . 10
2.6.8. Single host address . . . . . . . . . . . . . . . . . 11
2.6.9. Comments . . . . . . . . . . . . . . . . . . . . . . 11
2.7. Catalog zone version . . . . . . . . . . . . . . . . . . 11
2.8. List of member zones . . . . . . . . . . . . . . . . . . 12
2.9. Zone configuration properties . . . . . . . . . . . . . . 12
2.9.1. zone-soa-default-serial . . . . . . . . . . . . . . . 12
2.9.2. zone-soa-default-refresh . . . . . . . . . . . . . . 12
2.10. Zone properties specific to a member zone . . . . . . . . 12
2.11. Examples of catalog zones . . . . . . . . . . . . . . . . 13
3. Nameserver behavior and requirements . . . . . . . . . . . . 13
3.1. General requirements . . . . . . . . . . . . . . . . . . 13
3.2. Updating catalog zones . . . . . . . . . . . . . . . . . 14
3.3. Implementation notes . . . . . . . . . . . . . . . . . . 14
4. Security considerations . . . . . . . . . . . . . . . . . . . 15
5. IANA considerations . . . . . . . . . . . . . . . . . . . . . 15
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6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 16
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
7.1. Normative references . . . . . . . . . . . . . . . . . . 16
7.2. Informative references . . . . . . . . . . . . . . . . . 17
Appendix A. Glossary . . . . . . . . . . . . . . . . . . . . . . 17
Appendix B. Open issues and discussion (to be removed before
final publication) . . . . . . . . . . . . . . . . . 18
Appendix C. Change History (to be removed before final
publication) . . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction
DNS nameservers implement AXFR and IXFR for zone data synchronization
among a zone's primary its 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 manually, or via an external application layer,
synchronize such zone catalogs among primaries and their secondary
nameservers. 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 and associated
template zone configuration common to all its member zones. An
implementation of catalog zones MAY allow catalog zones to include
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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 differently to achieve
its purpose. Though this may be controversial, the situation is not
different from other similar zone-based representations such as
response-policy zones [RPZ]. However, none of the RR TYPEs used by
catalog zones can incur any additional section processing during DNS
QUERY. Other than being transmitted via zone transfers, catalog
zones do not participate in the DNS and are not intended to be served
via DNS QUERY [RFC1035].
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 2.5. Each zone
property has a name and an associated value of a specific data type.
Zone property value data types are described in Section 2.6. A list
of permitted zone property names and their data types is given in
Section 2.9.
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 2.6 describes how various zone property
value types are represented.
The CLASS field of the RR MUST be set to the value 1 (IN) [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 do not participate in the DNS and are not intended to be served
via DNS QUERY [RFC1035], but this memo does not restrict their use.
The RDLENGTH field contains the length of the RDATA field.
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The content of the RDATA field depends on the type of catalog zone
property value being represented. Section 2.6 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.
The SOA record's SERIAL, REFRESH, RETRY and EXPIRE fields [RFC1035]
are used during zone transfer. A catalog zone's SOA SERIAL field
MUST increase when an update is made to the catalog zone's contents.
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. Catalog zones do not participate in the DNS and are not
intended to be served via DNS QUERY [RFC1035], but this memo does not
restrict their use.
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. RR TYPEs to represent data
This section introduces new RR TYPEs to represent some types of data
for which no convenient representation is currently available. These
are used in Section 2.6. These are general-purpose RR TYPEs and
their use is not limited to catalog zones.
2.4.1. BOOL RR TYPE (boolean condition)
The BOOL RR TYPE represents a single boolean condition in its RDATA.
2.4.1.1. BOOL RDATA wire format
The BOOL RDATA consists of a single octet (RDLENGTH is 1). A zero
valued octet represents the false condition and a non-zero valued
octet represents the true condition. Implementations SHOULD generate
an octet value of 1 to represent true conditions.
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2.4.1.2. BOOL RDATA presentation format
The BOOL RDATA's presentation is represented with the mnemonic
"FALSE" for the false condition, and "TRUE" for the true condition.
The presentation is case-insensitive.
2.4.1.3. BOOL RR example
The following example shows BOOL RRs:
is-ready.example.org. 3600 IN BOOL TRUE
allow-query.example.org. 3600 IN BOOL False
2.4.2. FLOAT RR TYPE (floating-point value)
The FLOAT RR TYPE represents a value in IEEE 754 double-precision
floating-point representation in its RDATA.
2.4.2.1. FLOAT RDATA wire format
The FLOAT RDATA consists of a value in IEEE 754 double-precision
floating-point representation [IEEE.754.1985] in network byte order,
which occupies 8 octets (RDLENGTH is 8).
2.4.2.2. FLOAT RDATA presentation format
The FLOAT RDATA's presentation uses the representation of an
unsuffixed "floating constant" as defined in the C programming
language standard [ISO.9899.1990].
2.4.2.3. FLOAT RR example
The following example shows FLOAT RRs:
x.sample-color.example.org. 3600 IN FLOAT 0.8
y.sample-color.example.org. 3600 IN FLOAT 0.2
z.sample-color.example.org. 3600 IN FLOAT 0.5
2.4.3. INT RR TYPE (64-bit signed integer value)
The INT RR TYPE represents a 64-bit signed integer in its RDATA.
2.4.3.1. INT RDATA wire format
The INT RDATA consists of a 64-bit signed integer in two's complement
representation, in network byte order, which occupies 8 octets
(RDLENGTH is 8).
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2.4.3.2. INT RDATA presentation format
The INT RDATA's presentation 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.
Scanners must read any of the various formats possible. Printers
must output the RDATA in base-10 decimal format.
2.4.3.3. INT RR example
The following example shows a INT RR:
counter-increment.example.org. 3600 IN INT -0x1
2.4.4. UINT RR TYPE (64-bit unsigned integer value)
The UINT RR TYPE represents a 64-bit unsigned integer in its RDATA.
2.4.4.1. UINT RDATA wire format
The UINT RDATA consists of a 64-bit unsigned integer, in network byte
order, which occupies 8 octets (RDLENGTH is 8).
2.4.4.2. UINT RDATA presentation format
The UINT RDATA's presentation 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).
Scanners must read any of the various formats possible. Printers
must output the RDATA in base-10 decimal format.
2.4.4.3. UINT RR example
The following example shows a UINT RR:
max-query-rate.example.org. 3600 IN UINT 3600
2.5. 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
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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 2.9.
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 2.6.
2.6. Zone property value data types
2.6.1. 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 may look 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.
2.6.2. Booleans
A property with a boolean value is specified using a single BOOL RR
(see Section 2.4.1) 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.
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For example, if a catalog zone is named "catalog1.example.org." and
contains a property "active" with boolean value false, the
corresponding RR may look as follows:
active.catalog1.example.org. 3600 IN BOOL false
Here, "active" can contain multiple BOOL RRs at that node of the
domain name space [RFC1034]. The single boolean property SHOULD be
checked by the implementation.
2.6.3. Integers
A property with an integer value is specified using a single INT RR
(see Section 2.4.3) for signed integers, or UINT RR (see
Section 2.4.4) for 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.
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 may look as follows:
min-ttl.catalog1.example.org. 3600 IN UINT 300
Here, "min-ttl" can contain multiple UINT RRs at that node of the
domain name space [RFC1034]. The single integer property SHOULD be
checked by the implementation.
2.6.4. Floating-point values
A property with a floating-point value is specified using a single
FLOAT RR (see Section 2.4.2) 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 "decay-rate" with value 0.33333333, the
corresponding RR may look as follows:
decay-rate.catalog1.example.org. 3600 IN FLOAT 0.33333333
Here, "decay-rate" can contain multiple FLOAT RRs at that node of the
domain name space [RFC1034]. The single floating-point property
SHOULD be checked by the implementation.
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2.6.5. Single names
A property with a single 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 may look as follows:
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 name property SHOULD be checked by
the implementation.
2.6.6. Unordered list of 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 names as value is
specified using multiple PTR RRs [RFC1035] with owner name set to N,
and each RR's RDATA set to each 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 may look 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
name property SHOULD be checked by the implementation.
2.6.7. 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
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be described by the property that APL is used for. Note that the AFL
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" with value [192.0.2.0/24,
198.51.100.0/24] as the list of networks, the corresponding RR may
look as follows:
allow.catalog1.example.org. 3600 IN APL (1:192.0.2.0/24
1:198.51.100.0/24)
Here, "allow" 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.
2.6.8. Single host address
A single host address is represented using the list of network
addresses data type (see Section 2.6.7) with a suitable network and
prefix to result in a single network address.
2.6.9. 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.
2.7. Catalog zone version
The catalog zone 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 value in this property, but
they may be transferred as ordinary zones. For this memo, the
"version" property value MUST be set to 0.
For example, if a catalog zone is named "catalog1.example.org.", the
corresponding RR MUST look as follows:
version.catalog1.example.org. 3600 IN UINT 0
Here, "version" can contain multiple UINT RRs at that node of the
domain name space [RFC1034]. The single UINT RR property SHOULD be
checked by the implementation.
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2.8. List of member zones
The list of member zones are specified as an unordered list (see
Section 2.6.6) of 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 the entire name of a zone (that is
technically possible [RFC1035]) can be represented correctly.
For example, if a catalog zone is named "catalog1.example.org." and
lists 3 zones "example.com.", "example.net." and "example.org.", the
RRs may look as follows:
<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.
2.9. 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.
2.9.1. zone-soa-default-serial
TBD.
2.9.2. zone-soa-default-refresh
TBD.
2.10. 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.
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Let N be an absolute name formed by concatenating the member zone
name hash (see Appendix A) 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 2.6.1) value "Example", the corresponding RR may look as
follows:
prop0.<m-hash>.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 2.6.6) of two names
"a.example.com." and "b.example.com.", the corresponding RRs may look
as follows:
<hash>.prop2.<m-hash>.cat1.example.org. 3600 IN PTR a.example.com.
<hash>.prop2.<m-hash>.cat1.example.org. 3600 IN PTR b.example.com.
2.11. Examples of catalog zones
TBD.
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. Catalog zones do not
participate in the DNS and are not intended to be served via DNS
QUERY. 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.
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As with regular zones, primary and secondary nameservers for a
catalog zone may be operated by different administrators. The
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 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 MUST 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 query data from 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,
it may not be possible to perform these queries efficiently (or in
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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, it is a requirement that
catalog zone transfers MUST be authenticated using TSIG [RFC2845]. A
primary nameserver MUST NOT serve a catalog zone for transfer without
using TSIG and a secondary nameserver MUST abandon an update to a
catalog zone that was received without using TSIG.
DNS UPDATE [RFC2136] to catalog zones similarly MUST be authenticated
using TSIG.
Zone transfers of member zones MUST similarly be authenticated using
TSIG [RFC2845]. The TSIG shared secrets used for member zones are
identical to those used for the catalog zones. Details of the shared
secrets MUST NOT be mentioned anywhere in the catalog zone data.
Catalog zones do not need to be signed using DNSSEC. Their zone
transfers are authenticated by TSIG. Signed zones MUST be handled
normally by nameservers, and their contents MUST NOT be DNSSEC-
validated.
5. IANA considerations
This document defines new resource record types, titled BOOL, FLOAT,
INT, and UINT (see Section 2.4), assigned values as follows from the
Resource Record (RR) TYPEs space [to be removed upon publication:
https://www.iana.org/assignments/dns-parameters/dns-
parameters.xhtml#dns-parameters-11].
+-------+-------+------------------------------------------+
| TYPE | Value | Meaning |
+-------+-------+------------------------------------------+
| BOOL | TBD | Boolean value |
| FLOAT | TBD | IEEE 754 double-precision number |
| INT | TBD | 64-bit signed integer (two's complement) |
| UINT | TBD | 64-bit unsigned integer |
+-------+-------+------------------------------------------+
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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.
Thanks to Ray Bellis, Brian Conry, Evan Hunt, Witold Krecicki,
Victoria Risk for reviewing draft proposals and providing support,
comments and suggestions.
Thanks to BIND users who reviewed draft proposals and offered
comments and suggestions.
7. References
7.1. Normative references
[FIPS.180-1.1995]
National Institute of Standards and Technology, "Secure
Hash Standard", FIPS PUB 180-1, April 1995,
<http://www.itl.nist.gov/fipspubs/fip180-1.htm>.
[IEEE.754.1985]
Institute of Electrical and Electronics Engineers,
"Standard for Binary Floating-Point Arithmetic", IEEE
Standard 754, August 1985.
[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>.
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[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>.
[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>.
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.
[I-D.ietf-dnsop-dns-terminology]
Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
Terminology", draft-ietf-dnsop-dns-terminology-05 (work in
progress), September 2015.
[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.
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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 [I-D.ietf-dnsop-dns-terminology].
RDATA hash: The hexadecimal format 40-digit SHA-1 [FIPS.180-1.1995]
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.
Member zone name hash: The hexadecimal format 40-digit SHA-1
[FIPS.180-1.1995] digest, of a zone name in uncompressed wire
format.
Secondary nameserver: An authoritative server which uses zone
transfer to retrieve the zone. Also see
[I-D.ietf-dnsop-dns-terminology].
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.
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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.
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.
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Authors' Addresses
Stephen Morris
Internet Systems Consortium
950 Charter Street
Redwood City, CA 94063
US
Email: stephen@isc.org
URI: http://www.isc.org/
Mukund Sivaraman
Internet Systems Consortium
950 Charter Street
Redwood City, CA 94063
US
Email: muks@mukund.org
URI: http://www.isc.org/
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