Extensible Provisioning Protocol (EPP) mapping for DNS Time-To-Live (TTL) values

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 (), and DNAME records for IDN variants (). A and/or AAAA records may also be published for nameservers where required by DNS resolvers to avoid an infinite loop. Typically, the Time-To-Live value (TTL, see ) 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 and , respectively) which 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 to manage TTL values in response to changes in operational or security requirements.

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. In examples, "C:" represents lines sent by a protocol client and "S:" represents lines returned by a protocol server. Indentation and white space in 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, 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 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, 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.

This extension adds additional elements to the EPP domain and host mappings.

The <ttl:ttl> element is used to define TTL values for the DNS resource records associated with domain and host objects. <ttl:ttl> elements may have the following attributes, depending on whether it appears in a command or response frame:

"for", which is 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";
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 . Additionally, the record type MUST be registered with IANA.
"min", which MUST NOT be present in command frames but MAY be present in response frames (see ), and which is used by the server to indicate the lowest value that may be set;
"default", which MUST NOT be present in command frames but MAY be present in response frames (see ), and which is used by the server to indicate the default value;
"max", which MUST NOT be present in command frames but MAY be present in response frames (see ), and which is used by the server to indicate the highest value that may be 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.

The XML schema found in of this document restricts the content of <ttl:ttl> elements to be either:

a non-negative integer, indicating the value of the TTL in seconds, or
empty, in which case the server's default TTL for the given record type is to be applied.

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 is used to validate the values of the "custom" attribute is based on the expression found in , and 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 () are specified. Nevertheless, EPP servers which 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 actually published in the DNS for domain and host objects. 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:

NS;
DS (if the server also implements );
DNAME (if the server implements IDN variants using DNAME records).

Glue records are described in . Servers which implement host objects () MAY allow clients to specify TTL values for A and AAAA records for host objects. A server supporting host objects which 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 use the "host attribute" model (described in ) MAY allow clients to specify TTL values for A and AAAA records for domain objects.

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 attribute, which takes a boolean value with a default value of false. The semantics of this element are described in .

<ttl:info policy="true"/>

<ttl:ttl for="NS">3600<ttl:ttl>

<ttl:ttl for="NS" min="60" default="86400" max="172800">3600<ttl:ttl>

<ttl:ttl for="NS"/>

<ttl:ttl for="custom" custom="NEWRRTYPE">3600<ttl:ttl>

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:

The Default Mode (), which requests the inclusion of all non-default TTL values in the response; and
The Policy Mode (), which requests the inclusion of TTL information for all supported DNS record types in the response, along with the minimum, default and maximum values for those records.

If a server receives an <info> command for a domain or host object which 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" and "max" attributes. Example domain <info> command with a <ttl:info> element with a policy attribute that is 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 domain <info> response to a command with a <ttl:info> element with a policy attribute that is 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 host <info> command with a <ttl:info> element with a policy attribute that is 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 host <info> response to a command with a <ttl:info> element with a policy attribute that is 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>

If a server receives an <info> command for a domain or host object which includes a <ttl:info> element with a "policy" attribute 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" and "max" attributes. 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 domain <info> response providing the server policies: <?xml version="1.0" encoding="utf-8" standalone="no"?> <epp xmlns="urn:ietf:params:xml:ns:epp-1.0"> <response> <result code="1000"> <msg>Command completed successfully</msg> </result> <resData> <domain:infData xmlns:domain="urn:ietf:params:xml:ns:domain-1.0"> <domain:name>example.com</domain:name> <domain:roid>EXAMPLE1-REP</domain:roid> <domain:status s="ok"/> <domain:ns> <domain:hostObj>ns1.example.com</domain:hostObj> <domain:hostObj>ns1.example.net</domain:hostObj> </domain:ns> <domain:clID>ClientX</domain:clID> <domain:crID>ClientX</domain:crID> <domain:crDate>2023-11-08T10:14:55.0Z</domain:crDate> <domain:exDate>2024-11-08T10:14:55.0Z</domain:exDate> </domain:infData> </resData> <extension> <ttl:infData xmlns:ttl="urn:ietf:params:xml:ns:epp:ttl-1.0"> <ttl:ttl for="NS" min="3600" default="86400" max="172800">172800</ttl:ttl> <ttl:ttl for="DS" min="60" default="86400" max="172800">300</ttl:ttl> </ttl:infData> <secDNS:infData xmlns:secDNS="urn:ietf:params:xml:ns:secDNS-1.1"> <secDNS:dsData> <secDNS:keyTag>12345</secDNS:keyTag> <secDNS:alg>13</secDNS:alg> <secDNS:digestType>2</secDNS:digestType> <secDNS:digest>49FD46E6C4B45C55D4AC</secDNS:digest> </secDNS:dsData> </secDNS:infData> </extension> <trID> <clTRID>ABC-12345</clTRID> <svTRID>54322-XYZ</svTRID> </trID> </response> </epp> 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 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>

This extension defines an additional element for EPP <create> commands for domain and host objects. The <command> element of the <create> command frame MAY contain an <extension> element which MAY contain a <ttl:create> element. This element MUST contain one or more <ttl:ttl> records as described in . 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 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.

This extension defines an additional element for EPP <update> commands for domain and host objects. The <command> element of the <update> command frame MAY contain an <extension> element which MAY contain a <ttl:update> element. This element MUST contain one or more <ttl:ttl> records as described in . 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 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.

Servers SHOULD restrict the supported DNS record types in accordance with their own policy. For example, a server MAY allow clients to specify TTL values for DS records only. A server which receives a <create> or <update> command which 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" <info> command, as outlined in .

EPP servers which 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. EPP servers that use the "host attribute" model SHOULD use any NS, A and/or AAAA TTL values specified for the domain object when publishing NS, A and/or AAAA records derived from host attributes.

EPP server operators MAY, in order to address operational or security issues, 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 (), which provides a generalised method for EPP servers to notify clients of changes to objects under their sponsorship.

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 (which were chosen to allow any TTL permitted in DNS records), in order to prevent scenarios where an excessively high or low TTL causes operational issues on either side of the zone cut. 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).

A common operational mistake is changing of 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 least equal to the current 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.

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 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. describes how such out-of-band changes should be carried out.

Some malicious actors use a technique called "fast flux DNS" () 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 provide an interface for customers to configure TTL values for domain names should consider implementing controls to deter and mitigate abusive behaviour, such as those outlined in the "Current and Possible Mitigation Alternatives" section of .

An attacker who obtains access to a customer account at a domain registrar which supports this extension could make unauthorised 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 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.

This document uses URNs to describe XML namespaces and XML schemas conforming to a registry mechanism described in . The following URI assignment is requested of 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 Registration for the TTL XML schema: URI: urn:ietf:params:xml:schema:epp:ttl-1.0 Registrant Contact: IESG XML: See the "" section of this document

The EPP extension described in this document is to be registered by IANA in the Extensions for the "Extensible Provisioning Protocol (EPP)" registry described in . 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: IESG TLDs: Any IPR Disclosure: None Status: Active Notes: None

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>  <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>  <simpleType name="ttlOrNull"> <union memberTypes="ttl:emptyValue ttl:ttlValue"/> </simpleType>  <simpleType name="emptyValue"> <restriction base="token"> <length value="0"/> </restriction> </simpleType>  <simpleType name="ttlValue"> <restriction base="nonNegativeInteger"> <minInclusive value="0"/> <maxInclusive value="2147483647"/> </restriction> </simpleType>  <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>  <simpleType name="customRRType"> <restriction base="token"> <pattern value="A|[A-Z][A-Z0-9\-]*[A-Z0-9]"/> </restriction> </simpleType> </schema>

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

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

Further updates as suggested during IESG review.

Updates as suggested during IESG review.

Updates as suggested during AD review.
In the last paragraph of Section 3.2, make both lists of RR types be the same.
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.
Correct section in reference to RFC 6895 (thanks Jasdip Singh).
Minor typographic fixes (thanks Jasdip Singh).

Resolve remaining nit before IESG submission.

Updates as per the document shepherd's suggestions.

Updates as per the document shepherd's email to the list of 2024-06-10.

Fix double word in .

Changes resulting from the Dnsdir review:

Fixed example IPv6 addresses to use the preferred prefix 2001:DB8::.
Added paragraph to describing how clients can use the Policy Mode <info> command () to discover the DNS record types supported by the server.

Some wording changes suggested by James Gould and Tim Wicinski.

Some wording changes suggested by Rick Wilhelm.

Minor wording changes and nits reported by JG.

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.

removed the erroneous required="true" attribute from the min, default and max attributes of the responseTTLType type (thanks JG).
fixed the reference to RFC 6895 (thanks HS).

Add the Verisign EPP SDK to .
Add the <ttl:info> element and document how it affects server <info> responses.
Updated examples to exercise more of the schema.
Minor schema issue fixed.

Changed the for attribute to be an enumeration and added the custom attribute.
Added the min, default and max attributes.
Apply feedback from Jim Gould.

Rolled back the "straw man" syntax from 02. ttl:ttl now has a for attribute which can be any DNS record type. describes how the set of supported record types may be limited.
Removed the global/explicit models and just use the explicit model.
Removed the cascading effect where a TTL set on a domain affects subordinate hosts.

Renamed the ttl:seconds XSD type to ttl:container, and the ttl:nonNegativeInteger type to ttl:ttlType, to permit multiple TTL values.
Converted XML instances from artwork to source code.

Incorporate feedback from Jim Gould.
Add wording to describe how TTL values are jointly managed by both clients and servers.
Fix minimum/maximum TTL value and schema namespace (thanks Patrick Mevzek).
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).
Namespace changed from urn:ietf:params:xml:ns:ttl-1.0 to urn:ietf:params:xml:ns:epp:ttl-1.0.
Added discussion on EPP servers which use the host attribute model in (thanks Hugo Salgado).
Added a Change Log.

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