Registration Protocols Extensions (regext)
Internet Engineering Task Force (IETF) G. Brown
Internet-Draft
Request for Comments: 9803 ICANN
Intended status:
Category: Standards Track 7 January 2025
Expires: 11 July June 2025
ISSN: 2070-1721
Extensible Provisioning Protocol (EPP) mapping Mapping for DNS Time-To-Live Time-to-Live
(TTL) values
draft-ietf-regext-epp-ttl-18 Values
Abstract
This document describes an extension to the Extensible Provisioning
Protocol (EPP) that allows EPP clients to manage the Time-To-Live Time-to-Live
(TTL) value for domain name delegation records.
About this draft
This note is to be removed before publishing as an RFC.
The source for this draft, and an issue tracker, may can be found at
https://github.com/gbxyz/epp-ttl-extension.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions used Used in this document . . . . . . . . . . . . 4 This Document
1.2. Extension elements . . . . . . . . . . . . . . . . . . . 5 Elements
1.2.1. The <ttl:ttl> element . . . . . . . . . . . . . . . . 5 Element
1.2.1.1. Element content . . . . . . . . . . . . . . . . . 5 Content
1.2.1.2. Supported DNS record types . . . . . . . . . . . 6 Record Types
1.2.1.3. The <ttl:info> element . . . . . . . . . . . . . 7 Element
1.2.2. Examples . . . . . . . . . . . . . . . . . . . . . . 7
1.2.2.1. Explicit TTL value Value (<create> or <update>
command) . . . . . . . . . . . . . . . . . . . . . 7 Command)
1.2.2.2. Explicit TTL value Value (<info> policy mode) . . . . . 7 Policy Mode)
1.2.2.3. Empty value indicating default Value Indicating Default TTL (<create> or
<update> command, Command, <info> default mode) . . . . . . 7 Default Mode)
1.2.2.4. Custom record type Record Type (<create> or <update> command, Command,
<info> default mode) . . . . . . . . . . . . . . . 7 Default Mode)
2. EPP command mapping . . . . . . . . . . . . . . . . . . . . . 8 Command Mapping
2.1. EPP query commands . . . . . . . . . . . . . . . . . . . 8 Query Commands
2.1.1. EPP <info> command . . . . . . . . . . . . . . . . . 8 Command
2.1.1.1. Default Mode . . . . . . . . . . . . . . . . . . 8
2.1.1.2. Policy Mode . . . . . . . . . . . . . . . . . . . 11
2.2. EPP transform commands . . . . . . . . . . . . . . . . . 14 Transform Commands
2.2.1. EPP <create> command . . . . . . . . . . . . . . . . 14 Command
2.2.2. EPP <update> command . . . . . . . . . . . . . . . . 16 Command
3. Server processing Processing of TTL values . . . . . . . . . . . . . . . 18 Values
3.1. Permitted record types . . . . . . . . . . . . . . . . . 18 Record Types
3.2. Use of TTL values Values in delegation records . . . . . . . . . 18 Delegation Records
4. Out-of-band changes Out-of-Band Changes to TTL values . . . . . . . . . . . . . . 18 Values
5. Operational considerations . . . . . . . . . . . . . . . . . 18 Considerations
5.1. Operational impact Impact of TTL values . . . . . . . . . . . . 19 Values
5.2. When TTL values should be changed . . . . . . . . . . . . 19 Values Should Be Changed
5.3. Changes to server policy . . . . . . . . . . . . . . . . 19 Server Policy
6. Security considerations . . . . . . . . . . . . . . . . . . . 19 Considerations
6.1. Fast-flux Fast Flux DNS . . . . . . . . . . . . . . . . . . . . . . 20
6.2. Compromised user accounts . . . . . . . . . . . . . . . . 20 User Accounts
7. IANA considerations . . . . . . . . . . . . . . . . . . . . . 20 Considerations
7.1. XML namespace . . . . . . . . . . . . . . . . . . . . . . 20 Namespace
7.2. EPP extension registry . . . . . . . . . . . . . . . . . 21 Extension Registry
8. Formal syntax . . . . . . . . . . . . . . . . . . . . . . . . 21 Syntax
9. Implementation status . . . . . . . . . . . . . . . . . . . . 24
9.1. Verisign EPP SDK . . . . . . . . . . . . . . . . . . . . 25
9.2. Pepper EPP Client . . . . . . . . . . . . . . . . . . . . 25
10. Change log . . . . . . . . . . . . . . . . . . . . . . . . . 25
10.1. Changes from 17 to 18 . . . . . . . . . . . . . . . . . 25
10.2. Changes from 16 to 17 . . . . . . . . . . . . . . . . . 26
10.3. Changes from 15 to 16 . . . . . . . . . . . . . . . . . 26
10.4. Changes from 14 to 15 . . . . . . . . . . . . . . . . . 26
10.5. Changes from 13 to 14 . . . . . . . . . . . . . . . . . 26
10.6. Changes from 12 to 13 . . . . . . . . . . . . . . . . . 26
10.7. Changes from 11 to 12 . . . . . . . . . . . . . . . . . 27
10.8. Changes from 10 to 11 . . . . . . . . . . . . . . . . . 27
10.9. Changes from 09 to 10 . . . . . . . . . . . . . . . . . 27
10.10. Changes from 08 to 09 . . . . . . . . . . . . . . . . . 27
10.11. Changes from 07 to 08 . . . . . . . . . . . . . . . . . 27
10.12. Changes from 06 to 07 . . . . . . . . . . . . . . . . . 27
10.13. Changes from 05 to 06 . . . . . . . . . . . . . . . . . 27
10.14. Changes from 04 to 05 . . . . . . . . . . . . . . . . . 27
10.15. Changes from 04 to 05 . . . . . . . . . . . . . . . . . 27
10.16. Changes from 03 to 04 . . . . . . . . . . . . . . . . . 28
10.17. Changes from 02 to 03 . . . . . . . . . . . . . . . . . 28
10.18. Changes from 01 to 02 . . . . . . . . . . . . . . . . . 28
10.19. Changes from 00 to 01 . . . . . . . . . . . . . . . . . 28
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 29
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 29
12.1.
9.1. Normative references . . . . . . . . . . . . . . . . . . 29
12.2. References
9.2. Informative references . . . . . . . . . . . . . . . . . 30 References
Acknowledgments
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 31
1. Introduction
The principal output of any domain name registry system is a DNS zone
file, which contains the delegation record(s) for names registered
within a zone (such as a top-level domain). These records typically
include one or more NS records, but may also include DS records for
domains secured with DNSSEC ([RFC9364]), [RFC9364], and DNAME records for IDN
Internationalized Domain Name (IDN) variants ([RFC6927]). [RFC6927]. A and/or
AAAA records may also be published for nameservers where they are
required by DNS resolvers to avoid an infinite loop.
Typically, the Time-To-Live Time-to-Live (TTL) value (TTL, see (see Section 5 of [RFC9499])
of these records is determined by the registry operator. However, in
some circumstances it may be desirable to allow the sponsoring client
of a domain name to change the TTL values used for that domain's
delegation: for example, to reduce the amount of time required to
complete a change of DNS servers, DNSSEC deployment or key rollover,
or to allow for fast rollback of such changes.
This document describes an EPP extension to the domain name and host
object mappings (described in [RFC5731] and [RFC5732], respectively)
which
that allows the sponsor of a domain name or host object to change the
TTL values of the resource record(s) associated with that object. It
also describes how EPP servers should handle TTLs specified by EPP
clients and how both parties co-ordinate coordinate to manage TTL values in
response to changes in operational or security requirements.
1.1. Conventions used Used in this document This Document
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 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
In this document's examples, "C:" represents lines sent by a protocol
client and "S:" represents lines returned by a protocol server.
Indentation and white space in these examples are provided only to
illustrate element relationships and are not required features of
this protocol.
A protocol client that is authorized to manage an existing object is
described as a "sponsoring" client throughout this document.
XML is case sensitive. Unless stated otherwise, the XML
specifications and examples provided in this document MUST be
interpreted in the character case presented in order to develop a
conforming implementation.
EPP uses XML namespaces to provide an extensible object management
framework and to identify schemas required for XML instance parsing
and validation. These namespaces and schema definitions are used to
identify both the base protocol schema and the schemas for managed
objects.
The XML namespace prefixes used in these examples (such as the string
ttl in ttl:create) are solely for illustrative purposes. A
conforming implementation MUST NOT require the use of these or any
other specific namespace prefixes.
In accordance with Section 3.2.2.1 of XML Schema Part 2: Datatypes
[XSD-DATATYPES], the allowable lexical representations for the
xs:boolean datatype are the strings "0" and "false" for the concept
'false' and the strings "1" and "true" for the concept 'true'.
Implementations MUST support both styles of lexical representation.
1.2. Extension elements Elements
This extension adds additional elements to the EPP domain and host
mappings.
1.2.1. The <ttl:ttl> element Element
The <ttl:ttl> element is used to define TTL values for the DNS
resource records associated with domain and host objects.
<ttl:ttl> elements have the optional following attributes, depending
on whether they appear in an EPP command or response:
1. "for", which is
"for"
REQUIRED in both commands and responses, and
which specifies the DNS
record type to which the TTL value pertains. This attribute MUST
have one of the following values: "NS", "DS", "DNAME", "A", "AAAA"
or "custom";
2. "custom".
"custom"
If the value of the "for" attribute is "custom", then the
<ttl:ttl> element MUST also have a "custom" attribute containing a
DNS record type conforming with the regular expression in
Section 3.1 of [RFC6895]. Additionally, the record type MUST be
registered with IANA in [IANA-RRTYPES].
3. "min", which
"min"
MUST NOT be present in EPP commands but MAY be present in EPP
responses (see Section 2.1.1), and which 2.1.1). It is also used by the server to
indicate the lowest value that may be set;
4. "default", which set.
"default"
MUST NOT be present in EPP commands but MAY be present in EPP
responses (see Section 2.1.1), and which 2.1.1). It is also used by the server to
indicate the default value;
5. "max", which value.
"max"
MUST NOT be present in EPP commands but MAY be present in EPP
responses (see Section 2.1.1), and which 2.1.1). It is also used by the server to
indicate the highest value that may be set; set.
When present, the value of the "min" attribute MUST be lower than the
value of the "max" attribute. The "default" attribute MUST be
between the "min" and "max" values, inclusively.
1.2.1.1. Element content Content
The XML schema found in Section 8 of this document restricts the
content of <ttl:ttl> elements to be either:
1. a non-negative integer, indicating the value of the TTL in
seconds, or
2. empty, in which case the server's default TTL for the given
record type is to be applied.
1.2.1.2. Supported DNS record types Record Types
To facilitate forward compatibility with future changes to the DNS
protocol, this document does not enumerate or restrict the DNS record
types that can be included in the "custom" attribute of the <ttl:ttl>
element.
The regular expression which that is used to validate the values of the
"custom" attribute is based on the expression found in Section 3.1 of
[RFC6895], and it is intended to match both existing and future
RRTYPE mnemonics. This eliminates the need to update this document
in the event that new DNS records that exist above a zone cut
(Section 7 of [RFC9499]) are specified.
Nevertheless, EPP servers which that implement this extension MUST restrict
the DNS record types that are accepted in <create> and <update>
commands, and included in <info> responses, allowing only those types
that are (a) registered in [IANA-RRTYPES] and (b) appropriate for use
above a zone cut.
A server that receives a <create> or <update> command that attempts
to set TTL values for inapplicable DNS record types MUST respond with
a 2306 "Parameter value policy" error.
As an illustrative example, a server MAY allow clients to specify TTL
values for the following record types for domain objects:
1. NS;
2. DS (if the server also implements [RFC5910]);
3. DNAME (if the server implements IDN variants using DNAME
records).
1.2.1.2.1. Glue records Records
Glue records are described in Section 7 of [RFC9499].
Servers which that implement host objects ([RFC5732]) [RFC5732] MAY allow clients to
specify TTL values for A and AAAA records for host objects.
A server supporting host objects which that receives a command that
attempts to set TTL values for A and AAAA records on a domain object
MUST respond with a 2306 "Parameter value policy" error.
EPP servers which that use the "host attribute" host attribute model (described in
Section 1.1 of [RFC5731]) MAY allow clients to specify TTL values for
A and AAAA records for domain objects.
1.2.1.3. The <ttl:info> element Element
The <ttl:info> element is used by clients to request that the server
include additional information in <info> responses for domain and
host objects.
It has a single OPTIONAL policy "policy" attribute, which takes a boolean
value with a default value of false. "false".
The semantics of this element are described in Section 2.1.1.
1.2.1.3.1. Example
<ttl:info policy="true"/>
1.2.2. Examples
1.2.2.1. Explicit TTL value Value (<create> or <update> command) Command)
<ttl:ttl for="NS">3600</ttl:ttl>
1.2.2.2. Explicit TTL value Value (<info> policy mode) Policy Mode)
<ttl:ttl
for="NS"
min="60"
default="86400"
max="172800">3600</ttl:ttl>
1.2.2.3. Empty value indicating default Value Indicating Default TTL (<create> or <update>
command,
Command, <info> default mode) Default Mode)
<ttl:ttl for="NS"/>
1.2.2.4. Custom record type Record Type (<create> or <update> command, Command, <info>
default mode)
Default Mode)
<ttl:ttl
for="custom"
custom="NEWRRTYPE">3600</ttl:ttl>
2. EPP command mapping Command Mapping
2.1. EPP query commands Query Commands
2.1.1. EPP <info> command Command
This extension defines an additional element for EPP <info> commands
and responses for domain and host objects.
The EPP <info> command is extended to support two different modes:
1. The Default Mode (Section 2.1.1.1), which requests the inclusion
of all non-default TTL values in the response; and
2. The Policy Mode (Section 2.1.1.2), which requests the inclusion
of TTL information for all supported DNS record types in the
response, along with the minimum, default default, and maximum values for
those records.
2.1.1.1. Default Mode
If a server receives an <info> command for a domain or host object
which
that includes a <ttl:info> element with a "policy" attribute that is
"0" or "false", then the EPP response MUST contain <ttl:ttl> records
for all DNS record types that have non-default TTL values. These
elements MUST NOT have the "min", "default" "default", and "max" attributes.
Example
Below is an example domain <info> command with a <ttl:info> element
with a policy "policy" attribute that is false: "false":
C: <?xml version="1.0" encoding="UTF-8" standalone="no"?>
C: <epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
C: <command>
C: <info>
C: <domain:info
C: xmlns:domain="urn:ietf:params:xml:ns:domain-1.0">
C: <domain:name>example.com</domain:name>
C: </domain:info>
C: </info>
C: <extension>
C: <ttl:info
C: xmlns:ttl="urn:ietf:params:xml:ns:epp:ttl-1.0"
C: policy="false"/>
C: </extension>
C: </command>
C: </epp>
Example
Below is an example domain <info> response to a command with a
<ttl:info> element with a policy "policy" attribute that is false: "false":
S: <?xml version="1.0" encoding="utf-8" standalone="no"?>
S: <epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
S: <response>
S: <result code="1000">
S: <msg>Command completed successfully</msg>
S: </result>
S: <resData>
S: <domain:infData
S: xmlns:domain="urn:ietf:params:xml:ns:domain-1.0">
S: <domain:name>example.com</domain:name>
S: <domain:roid>EXAMPLE1-REP</domain:roid>
S: <domain:status s="ok"/>
S: <domain:ns>
S: <domain:hostObj>ns1.example.com</domain:hostObj>
S: <domain:hostObj>ns1.example.net</domain:hostObj>
S: </domain:ns>
S: <domain:clID>ClientX</domain:clID>
S: <domain:crID>ClientX</domain:crID>
S: <domain:crDate>2023-11-08T10:14:55.0Z</domain:crDate>
S: <domain:exDate>2024-11-08T10:14:55.0Z</domain:exDate>
S: </domain:infData>
S: </resData>
S: <extension>
S: <ttl:infData
S: xmlns:ttl="urn:ietf:params:xml:ns:epp:ttl-1.0">
S: <ttl:ttl for="NS">172800</ttl:ttl>
S: <ttl:ttl for="DS">300</ttl:ttl>
S: </ttl:infData>
S: <secDNS:infData
S: xmlns:secDNS="urn:ietf:params:xml:ns:secDNS-1.1">
S: <secDNS:dsData>
S: <secDNS:keyTag>12345</secDNS:keyTag>
S: <secDNS:alg>13</secDNS:alg>
S: <secDNS:digestType>2</secDNS:digestType>
S: <secDNS:digest>49FD46E6C4B45C55D4AC</secDNS:digest>
S: </secDNS:dsData>
S: </secDNS:infData>
S: </extension>
S: <trID>
S: <clTRID>ABC-12345</clTRID>
S: <svTRID>54322-XYZ</svTRID>
S: </trID>
S: </response>
S: </epp>
Example
Below is an example host <info> command with a <ttl:info> element
with a policy "policy" attribute that is false: "false":
C: <?xml version="1.0" encoding="UTF-8" standalone="no"?>
C: <epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
C: <command>
C: <info>
C: <host:info
C: xmlns:host="urn:ietf:params:xml:ns:host-1.0">
C: <host:name>ns1.example.com</host:name>
C: </host:info>
C: </info>
C: <extension>
C: <ttl:info
C: xmlns:ttl="urn:ietf:params:xml:ns:epp:ttl-1.0"
C: policy="false"/>
C: </extension>
C: </command>
C: </epp>
Example
Below is an example host <info> response to a command with a
<ttl:info> element with a policy "policy" attribute that is false: "false":
S: <?xml version="1.0" encoding="UTF-8" standalone="no"?>
S: <epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
S: <response>
S: <result code="1000">
S: <msg>Command completed successfully</msg>
S: </result>
S: <resData>
S: <host:infData
S: xmlns:host="urn:ietf:params:xml:ns:host-1.0">
S: <host:name>ns1.example.com</host:name>
S: <host:roid>NS1_EXAMPLE1-REP</host:roid>
S: <host:status s="ok"/>
S: <host:addr ip="v4">192.0.2.2</host:addr>
S: <host:addr ip="v6">2001:db8::8:800:200c:417a</host:addr>
S: <host:clID>ClientX</host:clID>
S: <host:crID>ClientX</host:crID>
S: <host:crDate>2023-11-08T10:14:55.0Z</host:crDate>
S: </host:infData>
S: </resData>
S: <extension>
S: <ttl:infData
S: xmlns:ttl="urn:ietf:params:xml:ns:epp:ttl-1.0">
S: <ttl:ttl for="A">172800</ttl:ttl>
S: <ttl:ttl for="AAAA">86400</ttl:ttl>
S: </ttl:infData>
S: </extension>
S: <trID>
S: <clTRID>ABC-12345</clTRID>
S: <svTRID>54322-XYZ</svTRID>
S: </trID>
S: </response>
S: </epp>
2.1.1.2. Policy Mode
If a server receives an <info> command for a domain or host object
which
that includes a <ttl:info> element with a "policy" attribute that is
"1" or "true", then the EPP response MUST contain <ttl:ttl> records
for all supported DNS record types, irrespective of whether those
record types are actually in use by the object in question. These
elements MUST have the "min", "default" "default", and "max" attributes.
Example
Below is an example domain <info> command requesting the server
policies:
C: <?xml version="1.0" encoding="UTF-8" standalone="no"?>
C: <epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
C: <command>
C: <info>
C: <domain:info
C: xmlns:domain="urn:ietf:params:xml:ns:domain-1.0">
C: <domain:name>example.com</domain:name>
C: </domain:info>
C: </info>
C: <extension>
C: <ttl:info
C: xmlns:ttl="urn:ietf:params:xml:ns:epp:ttl-1.0"
C: policy="true"/>
C: </extension>
C: </command>
C: </epp>
Example
Below is an example domain <info> response providing the server
policies:
S: <?xml version="1.0" encoding="utf-8" standalone="no"?>
S: <epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
S: <response>
S: <result code="1000">
S: <msg>Command completed successfully</msg>
S: </result>
S: <resData>
S: <domain:infData
S: xmlns:domain="urn:ietf:params:xml:ns:domain-1.0">
S: <domain:name>example.com</domain:name>
S: <domain:roid>EXAMPLE1-REP</domain:roid>
S: <domain:status s="ok"/>
S: <domain:ns>
S: <domain:hostObj>ns1.example.com</domain:hostObj>
S: <domain:hostObj>ns1.example.net</domain:hostObj>
S: </domain:ns>
S: <domain:clID>ClientX</domain:clID>
S: <domain:crID>ClientX</domain:crID>
S: <domain:crDate>2023-11-08T10:14:55.0Z</domain:crDate>
S: <domain:exDate>2024-11-08T10:14:55.0Z</domain:exDate>
S: </domain:infData>
S: </resData>
S: <extension>
S: <ttl:infData
S: xmlns:ttl="urn:ietf:params:xml:ns:epp:ttl-1.0">
S: <ttl:ttl for="NS"
S: min="3600"
S: default="86400"
S: max="172800">172800</ttl:ttl>
S: <ttl:ttl for="DS"
S: min="60"
S: default="86400"
S: max="172800">300</ttl:ttl>
S: </ttl:infData>
S: <secDNS:infData
S: xmlns:secDNS="urn:ietf:params:xml:ns:secDNS-1.1">
S: <secDNS:dsData>
S: <secDNS:keyTag>12345</secDNS:keyTag>
S: <secDNS:alg>13</secDNS:alg>
S: <secDNS:digestType>2</secDNS:digestType>
S: <secDNS:digest>49FD46E6C4B45C55D4AC</secDNS:digest>
S: </secDNS:dsData>
S: </secDNS:infData>
S: </extension>
S: <trID>
S: <clTRID>ABC-12345</clTRID>
S: <svTRID>54322-XYZ</svTRID>
S: </trID>
S: </response>
S: </epp>
Example
Below is an example host <info> command requesting the server
policies:
C: <?xml version="1.0" encoding="UTF-8" standalone="no"?>
C: <epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
C: <command>
C: <info>
C: <host:info
C: xmlns:host="urn:ietf:params:xml:ns:host-1.0">
C: <host:name>ns1.example.com</host:name>
C: </host:info>
C: </info>
C: <extension>
C: <ttl:info
C: xmlns:ttl="urn:ietf:params:xml:ns:epp:ttl-1.0"
C: policy="true"/>
C: </extension>
C: </command>
C: </epp>
Example
Below is an example host <info> response providing the server
policies:
S: <?xml version="1.0" encoding="UTF-8" standalone="no"?>
S: <epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
S: <response>
S: <result code="1000">
S: <msg>Command completed successfully</msg>
S: </result>
S: <resData>
S: <host:infData
S: xmlns:host="urn:ietf:params:xml:ns:host-1.0">
S: <host:name>ns1.example.com</host:name>
S: <host:roid>NS1_EXAMPLE1-REP</host:roid>
S: <host:status s="ok"/>
S: <host:addr ip="v4">192.0.2.2</host:addr>
S: <host:addr ip="v6">2001:db8::8:800:200c:417a</host:addr>
S: <host:clID>ClientX</host:clID>
S: <host:crID>ClientX</host:crID>
S: <host:crDate>2023-11-08T10:14:55.0Z</host:crDate>
S: </host:infData>
S: </resData>
S: <extension>
S: <ttl:infData
S: xmlns:ttl="urn:ietf:params:xml:ns:epp:ttl-1.0">
S: <ttl:ttl for="A"
S: min="3600"
S: default="86400"
S: max="172800">172800</ttl:ttl>
S: <ttl:ttl for="AAAA"
S: min="3600"
S: default="86400"
S: max="172800">86400</ttl:ttl>
S: </ttl:infData>
S: </extension>
S: <trID>
S: <clTRID>ABC-12345</clTRID>
S: <svTRID>54322-XYZ</svTRID>
S: </trID>
S: </response>
S: </epp>
2.2. EPP transform commands Transform Commands
2.2.1. EPP <create> command Command
This extension defines an additional element for EPP <create>
commands for domain and host objects.
The <command> element of the <create> command MAY contain an
<extension> element which that MAY contain a <ttl:create> element. This
element MUST contain one or more <ttl:ttl> records as described in
Section 1.2.
Example
Below is an example domain <create> command:
C: <?xml version="1.0" encoding="UTF-8" standalone="no"?>
C: <epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
C: <command>
C: <create>
C: <domain:create
C: xmlns:domain="urn:ietf:params:xml:ns:domain-1.0">
C: <domain:name>example.com</domain:name>
C: <domain:period unit="y">1</domain:period>
C: <domain:ns>
C: <domain:hostObj>ns1.example.com</domain:hostObj>
C: <domain:hostObj>ns1.example.net</domain:hostObj>
C: </domain:ns>
C: <domain:authInfo>
C: <domain:pw/>
C: </domain:authInfo>
C: </domain:create>
C: </create>
C: <extension>
C: <ttl:create
C: xmlns:ttl="urn:ietf:params:xml:ns:epp:ttl-1.0">
C: <ttl:ttl for="NS">172800</ttl:ttl>
C: <ttl:ttl for="DS">300</ttl:ttl>
C: </ttl:create>
C: <secDNS:create
C: xmlns:secDNS="urn:ietf:params:xml:ns:secDNS-1.1">
C: <secDNS:dsData>
C: <secDNS:keyTag>12345</secDNS:keyTag>
C: <secDNS:alg>13</secDNS:alg>
C: <secDNS:digestType>2</secDNS:digestType>
C: <secDNS:digest>49FD46E6C4B45C55D4AC</secDNS:digest>
C: </secDNS:dsData>
C: </secDNS:create>
C: </extension>
C: <clTRID>ABC-12345</clTRID>
C: </command>
C: </epp>
Example
Below is an example host <create> command:
C: <?xml version="1.0" encoding="UTF-8" standalone="no"?>
C: <epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
C: <command>
C: <create>
C: <host:create
C: xmlns:host="urn:ietf:params:xml:ns:host-1.0">
C: <host:name>ns1.example.com</host:name>
C: <host:addr ip="v4">192.0.2.2</host:addr>
C: <host:addr ip="v6">2001:db8::8:800:200c:417a</host:addr>
C: </host:create>
C: </create>
C: <extension>
C: <ttl:create
C: xmlns:ttl="urn:ietf:params:xml:ns:epp:ttl-1.0">
C: <ttl:ttl for="A"/>
C: <ttl:ttl for="AAAA">86400</ttl:ttl>
C: </ttl:create>
C: </extension>
C: <clTRID>ABC-12345</clTRID>
C: </command>
C: </epp>
If an EPP server receives a <create> command containing a TTL value
that is outside the server's permitted range, it MUST reject the
command with a 2004 "Parameter value range error" response.
2.2.2. EPP <update> command Command
This extension defines an additional element for EPP <update>
commands for domain and host objects.
The <command> element of the <update> command MAY contain an
<extension> element which that MAY contain a <ttl:update> element. This
element MUST contain one or more <ttl:ttl> records as described in
Section 1.2.
Example
Below is an example domain <update> command:
C: <?xml version="1.0" encoding="UTF-8" standalone="no"?>
C: <epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
C: <command>
C: <update>
C: <domain:update
C: xmlns:domain="urn:ietf:params:xml:ns:domain-1.0">
C: <domain:name>example.com</domain:name>
C: </domain:update>
C: </update>
C: <extension>
C: <ttl:update
C: xmlns:ttl="urn:ietf:params:xml:ns:epp:ttl-1.0">
C: <ttl:ttl for="NS"/>
C: <ttl:ttl for="custom"
C: custom="DELEG"/>
C: <ttl:ttl for="DS">86400</ttl:ttl>
C: </ttl:update>
C: </extension>
C: <clTRID>ABC-12345</clTRID>
C: </command>
C: </epp>
Example
Below is an example host <update> command:
C: <?xml version="1.0" encoding="UTF-8" standalone="no"?>
C: <epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
C: <command>
C: <update>
C: <host:update
C: xmlns:host="urn:ietf:params:xml:ns:host-1.0">
C: <host:name>ns1.example.com</host:name>
C: </host:update>
C: </update>
C: <extension>
C: <ttl:update
C: xmlns:ttl="urn:ietf:params:xml:ns:epp:ttl-1.0">
C: <ttl:ttl for="A">86400</ttl:ttl>
C: <ttl:ttl for="AAAA">3600</ttl:ttl>
C: </ttl:update>
C: </extension>
C: <clTRID>ABC-12345</clTRID>
C: </command>
C: </epp>
If an EPP server receives an <update> command containing a TTL value
that is outside the server's permitted range, it MUST reject the
command with a 2004 "Parameter value range error" response.
3. Server processing Processing of TTL values Values
3.1. Permitted record types Record Types
EPP servers MAY restrict the supported DNS record types. For
example, a server MAY allow clients to specify TTL values for DS
records only.
A server which that receives a <create> or <update> command which that includes a
restricted record type MUST respond with a 2306 "Parameter value
policy" error.
Clients can discover the DNS record types for which an EPP server
permits TTL values to be changed by performing a "Policy Mode" Policy Mode <info>
command, as outlined in Section 2.1.1.2.
3.2. Use of TTL values Values in delegation records Delegation Records
EPP servers which that implement this extension SHOULD use the values
provided by EPP clients for the TTL values of records published in
the DNS for domain and (if supported) host objects. Server operators
MAY disregard these values in order to address security and stability
issues, as described in Section 5 and Section 6.
EPP servers that use the "host attribute" host attribute model SHOULD use any NS, A A,
and/or AAAA TTL values specified for the domain object when
publishing NS, A A, and/or AAAA records derived from host attributes.
4. Out-of-band changes Out-of-Band Changes to TTL values
EPP server operators MAY, in Values
In order to address operational or security issues, EPP server
operators MAY make changes to TTL values out-of-band (that is, not in
response to an <update> command received from the sponsoring client).
Server operators MAY also implement automatic reset of TTL values, so
that they revert to the default value a certain amount of time after
an update has been made.
If a TTL value is changed out-of-band, EPP server operators MAY
notify the sponsoring client using the EPP Change Poll extension
([RFC8590]), Extension
[RFC8590], which provides a generalised generalized method for EPP servers to
notify clients of changes to objects under their sponsorship.
5. Operational considerations Considerations
5.1. Operational impact Impact of TTL values Values
Registry operators must consider the balance between registrants'
desire for changes to domains to be visible in the DNS quickly, and
the increased DNS query traffic that short TTLs can bring.
Registry operators SHOULD implement limits on the maximum and minimum
accepted TTL values that are narrower than the values permitted in
the XML schema in the Formal syntax Section 8 (which were chosen to allow any TTL
permitted in DNS records), records). This is in order to prevent scenarios
where an excessively high or low TTL causes operational issues on
either side of the zone cut.
Section 4 describes how server operators MAY unilaterally change TTL
values in order to address operational or security issues, or only
permit changes for limited time periods (after which TTLs revert to
the default).
5.2. When TTL values should be changed Values Should Be Changed
A common operational mistake is changing of the DNS record TTLs during
or after the planned change to the records themselves. This arises
due to a misunderstanding about how TTLs work.
It is RECOMMENDED that guidance be provided to users so they are
aware that changes to a TTL are only effective in shortening
transition periods if implemented a period of time — at (at least equal to
the current TTL — TTL) _before_ the planned change. The latency between
receipt of the <update> command and the actual publication of the
changes in the DNS should also be taken into consideration in this
calculation.
5.3. Changes to server policy Server Policy
Registry operators may change their policies relating to TTL values
from time to time. Previously configured TTL values may consequently
fall outside a newly-applied newly applied policy. This document places no
obligation on EPP server operators in respect of these values, and
server operators may, as part of a policy change, change the TTL
values specified by clients for domain and host objects. Section 4
describes how such out-of-band changes should be carried out.
6. Security considerations Considerations
6.1. Fast-flux Fast Flux DNS
Some malicious actors use a technique called "fast flux DNS"
([SAC-025])
[SAC-025] to rapidly change the DNS configuration for a zone in order
to evade takedown and law enforcement activity. Server operators
should take this into consideration when setting the lower limit on
TTL values, since a short TTL on delegations may enhance the
effectiveness of fast flux techniques on evasion.
Client implementations which that provide an interface for customers to
configure TTL values for domain names should consider implementing
controls to deter and mitigate abusive behaviour, behavior, such as those
outlined in the "Current and Possible Mitigation Alternatives"
section of [SAC-025].
6.2. Compromised user accounts User Accounts
An attacker who obtains access to a customer account at a domain
registrar which that supports this extension could make unauthorised unauthorized
changes to the NS and/or glue records for a domain, and then increase
the associated TTLs so that the changes persist in caches for a long
time after the attack has been detected.
Client implementations which that provide an interface for customers to
configure TTL values for domain names should consider implementing
upper limits in order to reduce the impact of account compromise, in
addition to best practices relating to credential management, multi-
factor authentication, risk-based access control, and so on.
7. IANA considerations Considerations
7.1. XML namespace Namespace
This document uses URNs to describe XML namespaces and XML schemas
conforming to a registry mechanism described in [RFC3688]. The
following URI assignment is requested of assignments have been made by IANA:
Registration for the TTL namespace:
*URI:* urn:ietf:params:xml:ns:epp:ttl-1.0
*Registrant Contact:* IESG
*XML:* None. Namespace URIs do not represent an XML specification specification.
Registration for the TTL XML schema:
*URI:* urn:ietf:params:xml:schema:epp:ttl-1.0
*Registrant Contact:* IESG
*XML:* See the "Formal syntax" section Section 8 of this document document.
7.2. EPP extension registry Extension Registry
The EPP extension described in this document is to be has been registered by
IANA in the Extensions "Extensions for the "Extensible Extensible Provisioning Protocol
(EPP)" registry described in [RFC7451]. The details of the
registration are as follows:
*Name of Extension:* Extensible Provisioning Protocol (EPP) Mapping
for DNS Time-To-Live (TTL) values
*Document Status:* Standards Track
*Reference:* URL of this document
*Registrant Name and Email Address:* RFC 9803
*Registrant:* IESG
*TLDs:* Any
*IPR Disclosure:* None
*Status:* Active
*Notes:* None
8. Formal syntax Syntax
The formal syntax presented here is a complete schema representation
of the extension suitable for automated validation of EPP XML
instances.
<?xml version="1.0" encoding="UTF-8"?>
<schema
xmlns="http://www.w3.org/2001/XMLSchema"
targetNamespace="urn:ietf:params:xml:ns:epp:ttl-1.0"
xmlns:ttl="urn:ietf:params:xml:ns:epp:ttl-1.0"
elementFormDefault="qualified">
<annotation>
<documentation>
Extensible Provisioning Protocol v1.0 extension
schema for Time-To-Live (TTL) values for domain
and host objects.
</documentation>
</annotation>
<element name="info">
<complexType>
<attribute name="policy" type="boolean" default="false"/>
</complexType>
</element>
<!--
<ttl> elements can appear in <create> and
<update> commands, and <info> responses
-->
<element name="create" type="ttl:commandContainer">
<unique name="uniqueRRTypeForCreate">
<selector xpath="ttl:ttl"/>
<field xpath="@for"/>
</unique>
</element>
<element name="update" type="ttl:commandContainer">
<unique name="uniqueRRTypeForUpdate">
<selector xpath="ttl:ttl"/>
<field xpath="@for"/>
</unique>
</element>
<element name="infData" type="ttl:responseContainer">
<unique name="uniqueRRTypeForInfo">
<selector xpath="ttl:ttl"/>
<field xpath="@for"/>
</unique>
</element>
<complexType name="commandContainer">
<sequence>
<element
name="ttl"
type="ttl:commandTTLType"
minOccurs="1"
maxOccurs="unbounded"/>
</sequence>
</complexType>
<complexType name="responseContainer">
<sequence>
<element
name="ttl"
type="ttl:responseTTLType"
minOccurs="1"
maxOccurs="unbounded"/>
</sequence>
</complexType>
<complexType name="commandTTLType">
<simpleContent>
<extension base="ttl:ttlOrNull">
<attribute
name="for"
type="ttl:rrType"
use="required"/>
<attribute
name="custom"
type="ttl:customRRType"/>
</extension>
</simpleContent>
</complexType>
<complexType name="responseTTLType">
<simpleContent>
<extension base="ttl:ttlOrNull">
<attribute
name="for"
type="ttl:rrType"
use="required"/>
<attribute
name="custom"
type="ttl:customRRType"/>
<attribute
name="min"
type="ttl:ttlValue"/>
<attribute
name="default"
type="ttl:ttlValue"/>
<attribute
name="max"
type="ttl:ttlValue"/>
</extension>
</simpleContent>
</complexType>
<!--
union type allowing the element to either contain
nothing or a TTL value
-->
<simpleType name="ttlOrNull">
<union
memberTypes="ttl:emptyValue ttl:ttlValue"/>
</simpleType>
<!-- empty value type -->
<simpleType name="emptyValue">
<restriction base="token">
<length value="0"/>
</restriction>
</simpleType>
<!-- TTL value type -->
<simpleType name="ttlValue">
<restriction base="nonNegativeInteger">
<minInclusive value="0"/>
<maxInclusive value="2147483647"/>
</restriction>
</simpleType>
<!-- resource record mnemonic type -->
<simpleType name="rrType">
<restriction base="token">
<enumeration value="NS" />
<enumeration value="DS" />
<enumeration value="DNAME" />
<enumeration value="A" />
<enumeration value="AAAA" />
<enumeration value="custom" />
</restriction>
</simpleType>
<!-- custom resource record type -->
<simpleType name="customRRType">
<restriction base="token">
<pattern value="A|[A-Z][A-Z0-9\-]*[A-Z0-9]"/>
</restriction>
</simpleType>
</schema>
9. Implementation status
This section is to be removed before publishing as an RFC.
9.1. Verisign EPP SDK
*Organization:* Verisign Inc.
*Name:* Verisign EPP SDK
*Description:* The Verisign EPP SDK includes both a full client
implementation and a full server stub implementation of this
specification.
*Level of maturity:* Development
*Coverage:* All aspects of the protocol are implemented.
*Licensing:* GNU Lesser General Public License
*Contact:* jgould@verisign.com
*URL:* https://www.verisign.com/en_US/channel-resources/domain-
registry-products/epp-sdks
9.2. Pepper EPP Client
*Name:* Pepper EPP Client
*Description:* The Pepper EPP client fully implements this
specification. The underlying Net::EPP:: Perl module also implements
this specification.
*Level of maturity:* Development
*Coverage:* All aspects of the protocol will be implemented.
*Licensing:* Perl Artistic License
*Contact:* The author of this document.
*URL:* https://github.com/gbxyz/pepper
10. Change log
This section is to be removed before publishing as an RFC.
10.1. Changes from 17 to 18
1. Add a space after the C: and S: line prefixes in examples.
2. Fixed the prefixing of lines in the example in Section 2.1.1.2
(thanks Tim Bray).
3. Fixed broken end tags in examples in Section 1.2.2 and the
capitalisation of IPv6 addresses (thanks Erik Kline).
4. Added normative reference to [IANA-RRTYPES].
5. Replaced references to "command/response frames" with "EPP
commands/responses".
6. Minor wording change in paragraph 2 of Section 1.2.1.
7. Clarified wording in Section 1.2.1.2.
8. Wordsmithing of Section 3 due to feedback from the IESG.
10.2. Changes from 16 to 17
1. Further updates as suggested during IESG review.
10.3. Changes from 15 to 16
1. Updates as suggested during IESG review.
10.4. Changes from 14 to 15
1. Updates as suggested during AD review.
2. In the last paragraph of Section 3.2, make both lists of RR types
be the same.
3. Update error codes to be consistent: 2004 (range error) when the
TTL value is outside the permitted range, and 2306 (policy error)
for an invalid record type.
4. Correct section in reference to RFC 6895 (thanks Jasdip Singh).
5. Minor typographic fixes (thanks Jasdip Singh).
10.5. Changes from 13 to 14
1. Resolve remaining nit before IESG submission.
10.6. Changes from 12 to 13
1. Updates as per the document shepherd's suggestions.
10.7. Changes from 11 to 12
1. Updates as per the document shepherd's email to the list of
2024-06-10.
10.8. Changes from 10 to 11
1. Fix double word in Section 3.2.
10.9. Changes from 09 to 10
Changes resulting from the Dnsdir review:
1. Fixed example IPv6 addresses to use the preferred prefix
2001:DB8::.
2. Added paragraph to Section 3.1 describing how clients can use the
Policy Mode <info> command (Section 2.1.1.2) to discover the DNS
record types supported by the server.
10.10. Changes from 08 to 09
1. Some wording changes suggested by James Gould and Tim Wicinski.
10.11. Changes from 07 to 08
1. Some wording changes suggested by Rick Wilhelm.
10.12. Changes from 06 to 07
1. Minor wording changes and nits reported by JG.
10.13. Changes from 05 to 06
1. Changed how <info> commands work so that a <ttl:info> element is
required in order for <ttl:ttl> elements to be included in the
response. Thanks to JG for this feedback.
10.14. Changes from 04 to 05
1. removed the erroneous required="true" attribute from the min,
default and max attributes of the responseTTLType type (thanks
JG).
2. fixed the reference to RFC 6895 (thanks HS).
10.15. Changes from 04 to 05
1. Add the Verisign EPP SDK to Section 9.
2. Add the <ttl:info> element and document how it affects server
<info> responses.
3. Updated examples to exercise more of the schema.
4. Minor schema issue fixed.
10.16. Changes from 03 to 04
1. Changed the for attribute to be an enumeration and added the
custom attribute.
2. Added the min, default and max attributes.
3. Apply feedback from Jim Gould.
10.17. Changes from 02 to 03
1. Rolled back the "straw man" syntax from 02. ttl:ttl now has a for
attribute which can be any DNS record type. Section 1.2.1.2
describes how the set of supported record types may be limited.
2. Removed the global/explicit models and just use the explicit
model.
3. Removed the cascading effect where a TTL set on a domain affects
subordinate hosts.
10.18. Changes from 01 to 02
1. Renamed the ttl:seconds XSD type to ttl:container, and the
ttl:nonNegativeInteger type to ttl:ttlType, to permit multiple
TTL values.
2. Converted XML instances from artwork to source code.
10.19. Changes from 00 to 01
1. Incorporate feedback from Jim Gould.
2. Add wording to describe how TTL values are jointly managed by
both clients and servers.
3. Fix minimum/maximum TTL value and schema namespace (thanks
Patrick Mevzek).
4. Moved text on how the server should handle impermissible TTL
values from the top of Section 4 to Sections 3.2.1 and 3.2.2
(thanks Rick Wilhelm).
5. Namespace changed from urn:ietf:params:xml:ns:ttl-1.0 to
urn:ietf:params:xml:ns:epp:ttl-1.0.
6. Added discussion on EPP servers which use the host attribute
model in Section 3.2 (thanks Hugo Salgado).
7. Added a Change Log (Section 10).
11. Acknowledgements
The author wishes to thank the following people for their advice and
feedback during the development of this document:
1. James Gould
2. Hugo Salgado
3. Patrick Mevzek
4. Rick Wilhelm
5. Marc Groeneweg
6. Ties de Kock
7. Tim Wicinski
8. Jasdip Singh
12. References
12.1.
9.1. Normative references References
[IANA-RRTYPES]
IANA, "Resource Record (RR) TYPEs",
<https://www.iana.org/assignments/dns-parameters/dns-
parameters.xhtml#dns-parameters-4>.
<https://www.iana.org/assignments/dns-parameters>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
[RFC5731] Hollenbeck, S., "Extensible Provisioning Protocol (EPP)
Domain Name Mapping", STD 69, RFC 5731,
DOI 10.17487/RFC5731, August 2009,
<https://www.rfc-editor.org/info/rfc5731>.
[RFC5732] Hollenbeck, S., "Extensible Provisioning Protocol (EPP)
Host Mapping", STD 69, RFC 5732, DOI 10.17487/RFC5732,
August 2009, <https://www.rfc-editor.org/info/rfc5732>.
[RFC5910] Gould, J. and S. Hollenbeck, "Domain Name System (DNS)
Security Extensions Mapping for the Extensible
Provisioning Protocol (EPP)", RFC 5910,
DOI 10.17487/RFC5910, May 2010,
<https://www.rfc-editor.org/info/rfc5910>.
[RFC6895] Eastlake 3rd, D., "Domain Name System (DNS) IANA
Considerations", BCP 42, RFC 6895, DOI 10.17487/RFC6895,
April 2013, <https://www.rfc-editor.org/info/rfc6895>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[XSD-DATATYPES]
World Wide Web Consortium (W3C),
Biron, P., Ed. and A. Malhotra, Ed., "XML Schema Part 2:
Datatypes Second Edition", W3C Recommendation, October
2004,
<https://www.w3.org/TR/2004/REC-xmlschema-2-20041028/>.
Latest version available at
<https://www.w3.org/TR/xmlschema-2/>.
12.2.
9.2. Informative references References
[RFC6927] Levine, J. and P. Hoffman, "Variants in Second-Level Names
Registered in Top-Level Domains", RFC 6927,
DOI 10.17487/RFC6927, May 2013,
<https://www.rfc-editor.org/info/rfc6927>.
[RFC7451] Hollenbeck, S., "Extension Registry for the Extensible
Provisioning Protocol", RFC 7451, DOI 10.17487/RFC7451,
February 2015, <https://www.rfc-editor.org/info/rfc7451>.
[RFC8590] Gould, J. and K. Feher, "Change Poll Extension for the
Extensible Provisioning Protocol (EPP)", RFC 8590,
DOI 10.17487/RFC8590, May 2019,
<https://www.rfc-editor.org/info/rfc8590>.
[RFC9364] Hoffman, P., "DNS Security Extensions (DNSSEC)", BCP 237,
RFC 9364, DOI 10.17487/RFC9364, February 2023,
<https://www.rfc-editor.org/info/rfc9364>.
[RFC9499] Hoffman, P. and K. Fujiwara, "DNS Terminology", BCP 219,
RFC 9499, DOI 10.17487/RFC9499, March 2024,
<https://www.rfc-editor.org/info/rfc9499>.
[SAC-025] ICANN Security and Stability Advisory Committee (SSAC),
"SSAC Advisory on Fast Flux Hosting and DNS", SAC 25, 025,
January 2008,
<https://www.icann.org/en/system/files/files/sac-
025-en.pdf>.
Acknowledgments
The author wishes to thank the following people for their advice and
feedback during the development of this document:
* James Gould
* Hugo Salgado
* Patrick Mevzek
* Rick Wilhelm
* Marc Groeneweg
* Ties de Kock
* Tim Wicinski
* Jasdip Singh
Author's Address
Gavin Brown
ICANN
12025 Waterfront Drive, Suite 300
Los Angeles, CA 90292
United States of America
Email: gavin.brown@icann.org
URI: https://www.icann.org/