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OPS regext Registrar Registry Internet resource domain name DNS configuration resource record validity This document specifies an extension to the Registration Data Access Protocol (RDAP), which allows the Time-to-Live (TTL) values for relevant DNS record types to be included in RDAP responses.

Introduction The Registration Data Access Protocol (RDAP) provides access to information about Internet resources (domain names, autonomous system numbers, and IP addresses). While RFC 9083 allows RDAP server operators to provide information about the content of the "NS", "DS", "A", and "AAAA" RRset(s) (see ), which are published in the DNS for a given registry object (domain or host object), it does not provide a mechanism to allow the Time-to-Live (TTL) values (see ) of those RRsets to be included in responses. Inclusion of these values in RDAP responses (in addition to nameservers, glue IP addresses, and Delegation Signer (DS) records) allows out-of-band debugging of the DNS configuration of troublesome domain names. This document describes how TTL information can be included in domain and nameserver objects in RDAP responses. As per , TTL values are applicable to RRsets rather than individual records.

Conventions Used in 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 when, and only when, they appear in all capitals, as shown here. This document uses terms defined in Section of RFC 9083 .

RDAP Response Specification Servers that support this extension MAY include a "ttl0_data" member in any domain (Section of RFC 9083 ) and nameserver (Section of RFC 9083 ) objects included in RDAP responses. As per Section of RFC 9083 , clients that do not implement this specification SHOULD ignore the "ttl0_data" member. The "ttl0_data" member is an object that has the following members:

• A "values" member, which is an object that maps DNS record type mnemonics to TTL values; and
• An OPTIONAL "remarks" member, which is an array of remarks (see Section of RFC 9083 ).

As specified in , a TTL value is "an unsigned number, with a minimum value of 0, and a maximum value of 2147483647. That is, a maximum of 2^31 - 1". TTL values MUST be represented as JSON numbers with no fractional component and no exponent notation. The TTL values included in "ttl0_data" members MUST reflect the TTL values as provisioned in the registry database, not the remaining TTL of DNS records as observed from live DNS queries. An example domain object with a valid "ttl0_data" member is provided below. Readers should refer to RFC 9083 for a description of the other objects listed in the example. An example nameserver object with a valid "ttl0_data" member is provided below.

DNS Record Types and TTL Values The DNS record type mnemonics that appear as the member names in "values" objects MUST be in all capitals and MUST be registered with IANA in . TTL values MUST be unsigned integers in the range 0-2147483647 as per .

RDAP Conformance Servers returning responses containing TTL values MUST include the string "ttl0" in the "rdapConformance" array.

Operational Considerations

RDAP Servers This specification is complementary to the Extensible Provisioning Protocol (EPP) and the EPP Mapping for DNS Time-to-Live (TTL) Values , but registry operators do not need to implement that extension in their EPP servers in order to implement this RDAP extension.

RDAP Clients Many RDAP clients make use of frameworks, which automatically "hydrate" objects using JSON data received in RDAP responses. As a result, RDAP clients that use these frameworks should explicitly carve out the "values" member of "ttl0_data" members. Since the list of record types appearing in "ttl0_data" members may change with time, clients that implement this extension MUST accept responses containing values for all valid DNS record types and SHOULD periodically update the list of valid DNS record types to align with , to avoid discarding a recently added record type.

IANA Considerations IANA has registered the following value in the "RDAP Extensions" registry :

Extension Identifier:

ttl0

Registry Operator:

Any

Specification:

RFC 10037

Contact:

IETF

Intended Usage:

This extension describes how DNS TTL values can be included in RDAP responses.

Security Considerations Security services for the extension specified in this document are described in RFC 7481 . This document only concerns itself with the representation of configured TTL values for domain and host objects. The security implications of how those TTL values are determined, assigned, or modified within a registry system are out of scope. Readers are referred to for further discussion.

References Normative References IANA IANA Informative References

Acknowledgements The author wishes to thank the following for their constructive feedback and advice during the development of this document: , , , , , , , , , , , and .