YANG Types for DNS
Classes and Resource Record Types
CZ.NIC
Czech Republic
ladislav.lhotka@nic.cz
Internet Systems Consortium
Czech Republic
pspacek@isc.org
Operations and Management
DNSOP Working Group
IANA registry
DNA Parameters
This document introduces the YANG
module "iana-dns-class-rr-type", which contains derived types
reflecting two IANA registries: DNS CLASSes and Resource Record
(RR) TYPEs. These YANG types are intended as the minimum basis for
future data modeling work.
YANG has become a de facto standard
as a language for modeling configuration and state data, as well
as specifying management operations and asynchronous
notifications. It is reasonable to expect that the approach
based on utilizing such data models along with standard
management protocols such as NETCONF
and RESTCONF can be effectively used in
DNS operations, too. In fact, several efforts are currently
underway that attempt to use NETCONF or RESTCONF for configuring
and managing
- authoritative servers,
- resolvers, and
- zone data.
While it is possible to use the management protocols
mentioned above with ad hoc or proprietary data models, their
real potential can be realized only if there is a (completely or
partly) unified data model supported by multiple DNS software
implementations. Operators can then, for instance, run several
DNS server implementations in parallel, and use a common
configuration and management interface and data for all of
them. Also, it becomes considerably easier to migrate to another
implementation.
Based on the previous experience from the IETF Routing Area,
it is to be expected that the development of unified data models
for DNS will be a lengthy and complicated process that will
require active cooperation and compromise from the vendors and
developers of major DNS server platforms. Nevertheless, it is
likely that any DNS-related data modeling effort will need to
use various DNS parameters and enumerations that are specified
in several IANA registries. For use with YANG, these parameters
and enumerations have to be translated into corresponding YANG
types or other structures. Such translations should be
straightforward and relatively uncontroversial.
This document provides a translation of two fundamental
DNS-related IANA registries to YANG. It contains the initial
version of the YANG module "iana-dns-class-rr-type", which
defines derived types for the common parameters of DNS resource
records (RR): class and type. These YANG types, "dns-class" and
"rr-type", reflect the IANA registries "DNS CLASSes" and
"Resource Record (RR) TYPEs" .
contains an XSLT 1.0 stylesheet
that is intended to be used by IANA for generating the initial
version of the "iana-dns-class-rr-type" YANG
module. Subsequently, whenever a new class or RR type is added
to the above registries, IANA will also update the
"iana-dns-class-rr-type" YANG module, following the instructions
in below.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED",
"MAY", and "OPTIONAL" in this document are to be interpreted as
described in BCP 14
when, and only when, they appear in all capitals, as shown here.
The terminology for describing YANG data models can be found
in . DNS terminology used in this
document can be found in and .
At the time of writing, the "Domain Name System
(DNS) Parameters" contains
altogether thirteen registries. The YANG module
"iana-dns-class-rr-type" defines derived types corresponding to
only two of the registries that are essential for data models
involving zone data, namely "DNS CLASSes" and "Resource Record
(RR) TYPEs". It is expected that the remaining registries in
, as well as other
DNS-related IANA registries, will be analogously reflected in
future YANG modules as necessary. This way, an appropriate
combination of YANG modules can be chosen depending on which
YANG types are needed for a given data modeling purpose.
The registries "DNS CLASSes" and "Resource Record (RR) TYPEs"
are transformed into YANG enumeration types "dns-class-name" and
"rr-type-name", respectively. This is the initial fragment of
the former:
typedef dns-class-name {
type enumeration {
enum IN {
value 1;
description
"Internet (IN)";
reference
"RFC 1035";
}
...
}
...
}
The other derived type, "rr-type-name", is defined
similarly.
introduced the option of specifying
a class or RR type via its assigned decimal number as an
alternative to the mnemonic name. For example, the "IN" class
can be equivalently written as "CLASS1", and "AAAA" type can be
written as "TYPE28".
Accordingly, the derived types "dns-class" and "rr-type" are
defined in the YANG module as a union of two member types:
- 16-bit decimal integer ("uint16")
- mnemonic name belonging to the enumerations
"dns-class-name" and "rr-type-name", respectively.
For instance, the "rr-type" type is defined as follows:
typedef rr-type {
type union {
type uint16;
type rr-type-name;
}
description
"This type allows reference to a DNS resource record type
using either the assigned mnemonic name or numeric value.";
}
As unassigned and reserved class and RR type values are not
included in the mnemonic name enumerations, they can only be specified
using their decimal values.
This section deals with actions and processes necessary for
IANA to undertake to maintain the "iana-dns-class-rr-type" YANG
module. This YANG module is intended to reflect the "DNS
CLASSes" and "Resource Record (RR) TYPEs" registries in . The most recent version of the
YANG module is available from the "YANG Parameters" registry .
With the publication of this document, IANA has created and posted the initial version
of the "iana-dns-class-rr-type" YANG module by applying the XSLT stylesheet from
to the XML version of .
IANA has added this note to the "iana-dns-class-rr-type" item
of the "YANG Module Names" registry :
Classes and types of DNS resource records must not be directly
added to the "iana-dns-class-rr-type" YANG module. They must
instead be added to the "DNS CLASSes" and "Resource Record
(RR) TYPEs" registries, respectively.
When a new DNS class or RR type is added to the "DNS CLASSes"
or "Resource Record (RR) TYPEs" registry, a new "enum" statement
SHALL be added to the "dns-class-name" or "rr-type-name" type,
respectively. The assigned name defined by the "enum" statement
SHALL be the same as the mnemonic name of the new class or
type. The following substatements to the "enum" statement SHALL
be defined:
- "value":
- Use the decimal value from the registry.
- "status":
- Include only if a class or type registration has been
deprecated or obsoleted. IANA "deprecated" maps to YANG status
"deprecated", and IANA "obsolete" maps to YANG status "obsolete".
- "description":
- Replicate the corresponding information from the registry,
namely the full name of the new DNS class, or the meaning of
the new RR type, if any.
- "reference":
- Replicate the reference(s) from the registry.
Unassigned or reserved values SHALL NOT be included in the
"dns-class-name" and "rr-type-name" enumeration types.
Each time the "iana-dns-class-rr-type" YANG module is updated, a new
"revision" statement SHALL be added before the existing
"revision" statements.
IANA has added this note to the "DNS CLASSes" and
"Resource Record (RR) TYPEs" registries:
When this registry is modified, the YANG module
"iana-dns-class-rr-type" must be updated as defined in [RFC9108].
The "Reference" text in the "DNS CLASSes" registry has been
updated as follows:
OLD:
[RFC6895]
NEW:
[RFC6895][RFC9108]
The "Reference" text in the "Resource Record (RR) TYPEs"
registry has been updated as follows:
OLD:
[RFC6895][RFC1035]
NEW:
[RFC6895][RFC1035][RFC9108]
This document registers a URI in the "IETF XML Registry"
. The following registration has been
made:
- URI:
- urn:ietf:params:xml:ns:yang:iana-dns-class-rr-type
- Registrant Contact:
- The IESG.
- XML:
- N/A; the requested URI is an XML namespace.
This document registers a YANG module in the "YANG Module
Names" registry . The following
registration has been made:
- Name:
- iana-dns-class-rr-type
- Namespace:
- urn:ietf:params:xml:ns:yang:iana-dns-class-rr-type
- Prefix:
- dnsct
- Reference:
- RFC 9108
This document translates two IANA registries into YANG data
types and otherwise introduces no technology or
protocol. The definitions themselves have no security impact on
the Internet, but their use in concrete YANG modules might
have. The security considerations spelled out in the YANG
specification apply to this document
as well.
References
Domain Name System (DNS) Parameters
IANA
YANG Parameters
IANA
XSL Transformations (XSLT) Version 1.0
This appendix contains an XSLT 1.0 stylesheet that is to be used to
generate the initial revision of the "iana-dns-class-rr-type"
YANG module. This is achieved by applying the stylesheet to the
XML version of the IANA registry "Domain Name System (DNS)
Parameters" that was
current at the time this document was published.
Using the ubiquitous xsltproc tool, the YANG module text can
be generated with this command:
$ xsltproc iana-dns-class-rr-type.xsl dns-parameters.xml
"
'
module iana-dns-class-rr-type {
yang-version 1.1;
namespace
"urn:ietf:params:xml:ns:yang:iana-dns-class-rr-type";
prefix dnsct;
organization
"Internet Assigned Numbers Authority (IANA)";
contact
" Internet Assigned Numbers Authority
Postal: ICANN
12025 Waterfront Drive, Suite 300
Los Angeles, CA 90094
Tel: +1 424 254 5300
<mailto:iana@iana.org>";
description
"This YANG module translates IANA registries 'DNS CLASSes' and
'Resource Record (RR) TYPEs' to YANG-derived types.
Copyright (c) 2021 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject to
the license terms contained in, the Simplified BSD License set
forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module was generated from
the corresponding IANA registries using an XSLT stylesheet
from Appendix A of RFC 9108
(https://www.rfc-editor.org/info/rfc9108); see the RFC itself
for full legal notices.";
reference
"IANA 'Domain Name System (DNS) Parameters' registry
https://www.iana.org/assignments/dns-parameters";
{
value
status obsolete;
reference
"
-
}
}
description
"Initial revision.";
reference
"RFC 9108: YANG Types for DNS Classes and Resource Record
Types";
}
/* Typedefs */
typedef dns-class-name {
type enumeration {
}
description
"This enumeration type defines mnemonic names and corresponding
numeric values of DNS classes.";
reference
"RFC 6895: Domain Name System (DNS) IANA Considerations";
}
typedef dns-class {
type union {
type uint16;
type dns-class-name;
}
description
"This type allows reference to a DNS class using either the
assigned mnemonic name or numeric value.";
}
typedef rr-type-name {
type enumeration {
}
description
"This enumeration type defines mnemonic names and corresponding
numeric values of DNS resource record types.";
reference
"- RFC 6895: Domain Name System (DNS) IANA Considerations
- RFC 1035: Domain names - implementation and specification";
}
typedef rr-type {
type union {
type uint16;
type rr-type-name;
}
description
"This type allows reference to a DNS resource record type
using either the assigned mnemonic name or numeric value.";
}
description
";
-
]]>