Registration Data Access Protocol (RDAP) Object Tagging
A hyphen and a short provider tag on the end of an RDAP handle tell clients which server to ask.
Hollenbeck, S. and A. Newton, "Registration Data Access Protocol (RDAP) Object Tagging", BCP 221, RFC 8521, DOI 10.17487/RFC8521, November 2018, <https://www.rfc-editor.org/info/rfc8521>.
@misc{rfc8521,
series = {Request for Comments},
number = 8521,
howpublished = {RFC 8521},
publisher = {RFC Editor},
doi = {10.17487/RFC8521},
url = {https://www.rfc-editor.org/info/rfc8521},
author = {S. Hollenbeck and A. Newton},
title = {{Registration Data Access Protocol (RDAP) Object Tagging}},
pagetotal = 13,
year = 2018,
month = nov,
} RFC text
Contents
Internet Engineering Task Force (IETF) S. Hollenbeck
Request for Comments: 8521 Verisign Labs
BCP: 221 A. Newton
Updates: 7484 ARIN
Category: Best Current Practice November 2018
ISSN: 2070-1721
Registration Data Access Protocol (RDAP) Object Tagging
Abstract
The Registration Data Access Protocol (RDAP) includes a method that
can be used to identify the authoritative server for processing
domain name, IP address, and autonomous system number queries. The
method does not describe how to identify the authoritative server for
processing other RDAP query types, such as entity queries. This
limitation exists because the identifiers associated with these query
types are typically unstructured. This document updates RFC 7484 by
describing an operational practice that can be used to add structure
to RDAP identifiers and that makes it possible to identify the
authoritative server for additional RDAP queries.
Status of This Memo
This memo documents an Internet Best Current Practice.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
BCPs is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8521.
Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Object Naming Practice . . . . . . . . . . . . . . . . . . . 3
3. Bootstrap Service Registry for Provider Object Tags . . . . . 9
3.1. Registration Procedure . . . . . . . . . . . . . . . . . 10
4. RDAP Conformance . . . . . . . . . . . . . . . . . . . . . . 10
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
5.1. Bootstrap Service Registry Structure . . . . . . . . . . 11
5.2. RDAP Extensions Registry . . . . . . . . . . . . . . . . 11
6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.1. Normative References . . . . . . . . . . . . . . . . . . 12
7.2. Informative References . . . . . . . . . . . . . . . . . 12
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction
The Registration Data Access Protocol (RDAP) includes a method
[RFC7484] that can be used to identify the authoritative server for
processing domain name, IP address, and Autonomous System Number
(ASN) queries. This method works because each of these data elements
is structured in a way that facilitates automated parsing of the
element and association of the data element with a particular RDAP
service provider. For example, domain names include labels (such as
"com", "net", and "org") that are associated with specific service
providers.
As noted in Section 9 of RFC 7484 [RFC7484], the method does not
describe how to identify the authoritative server for processing
entity queries, name server queries, help queries, or queries using
certain search patterns. This limitation exists because the
identifiers bound to these queries are typically not structured in a
way that makes it easy to associate an identifier with a specific
service provider. This document describes an operational practice
that can be used to add structure to RDAP identifiers and makes it
possible to identify the authoritative server for additional RDAP
queries.
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.
2. Object Naming Practice
Tagging object identifiers with a service provider tag makes it
possible to identify the authoritative server for processing an RDAP
query using the method described in RFC 7484 [RFC7484]. A service
provider tag is constructed by prepending the Unicode HYPHEN-MINUS
character "-" (U+002D, described as an "unreserved" character in RFC
3986 [RFC3986]) to an IANA-registered value that represents the
service provider. For example, a tag for a service provider
identified by the string value "ARIN" is represented as "-ARIN".
In combination with the rdapConformance attribute described in
Section 4, service provider tags are concatenated to the end of RDAP
query object identifiers to unambiguously identify the authoritative
server for processing an RDAP query. Building on the example from
Section 3.1.5 of RFC 7482 [RFC7482], an RDAP entity handle can be
constructed to allow an RDAP client to bootstrap an entity query.
The following identifier is used to find information for the entity
associated with handle "XXXX" at service provider "ARIN":
XXXX-ARIN
Clients that wish to bootstrap an entity query can parse this
identifier into distinct handle and service provider identifier
elements. Handles can themselves contain HYPHEN-MINUS characters;
the service provider identifier is found following the last HYPHEN-
MINUS character in the tagged identifier. The service provider
identifier is used to retrieve a base RDAP URL from an IANA registry.
The base URL and entity handle are then used to form a complete RDAP
query path segment. For example, if the base RDAP URL
"https://example.com/rdap/" is associated with service provider
"YYYY" in an IANA registry, an RDAP client will parse a tagged entity
identifier "XXXX-YYYY" into distinct handle ("XXXX") and service
provider ("YYYY") identifiers. The service provider identifier
"YYYY" is used to query an IANA registry to retrieve the base RDAP
URL "https://example.com/rdap/". The RDAP query URL is formed using
the base RDAP URL and entity path segment described in Section 3.1.5
of RFC 7482 [RFC7482] and using "XXXX-YYY" as the value of the handle
identifier. The complete RDAP query URL becomes
"https://example.com/rdap/entity/XXXX-YYYY".
Implementation of this practice requires tagging of unstructured
potential query identifiers in RDAP responses. Consider these elided
examples ("..." is used to note elided response objects) from
Section 5.3 of RFC 7483 [RFC7483] in which the handle identifiers
have been tagged with service provider tags "RIR", "DNR", and "ABC",
respectively:
{
"objectClassName" : "domain",
"handle" : "XXXX-RIR",
"ldhName" : "0.2.192.in-addr.arpa",
"nameservers" :
[
...
],
"secureDNS":
{
...
},
"remarks" :
[
...
],
"links" :
[
...
],
"events" :
[
...
],
"entities" :
[
{
"objectClassName" : "entity",
"handle" : "XXXX-RIR",
"vcardArray":
[
...
],
"roles" : [ "registrant" ],
"remarks" :
[
...
],
"links" :
[
...
],
"events" :
[
...
]
}
],
"network" :
{
"objectClassName" : "ip network",
"handle" : "XXXX-RIR",
"startAddress" : "192.0.2.0",
"endAddress" : "192.0.2.255",
"ipVersion" : "v4",
"name": "NET-RTR-1",
"type" : "DIRECT ALLOCATION",
"country" : "AU",
"parentHandle" : "YYYY-RIR",
"status" : [ "active" ]
}
}
Figure 1
{
"objectClassName" : "domain",
"handle" : "XXXX-YYY-DNR",
"ldhName" : "xn--fo-5ja.example",
"unicodeName" : "foo.example",
"variants" :
[
...
],
"status" : [ "locked", "transfer prohibited" ],
"publicIds":
[
...
],
"nameservers" :
[
{
"objectClassName" : "nameserver",
"handle" : "XXXX-DNR",
"ldhName" : "ns1.example.com",
"status" : [ "active" ],
"ipAddresses" :
{
...
},
"remarks" :
[
...
],
"links" :
[
...
],
"events" :
[
...
]
},
{
"objectClassName" : "nameserver",
"handle" : "XXXX-DNR",
"ldhName" : "ns2.example.com",
"status" : [ "active" ],
"ipAddresses" :
{
...
},
"remarks" :
[
...
],
"links" :
[
...
],
"events" :
[
...
]
}
],
"secureDNS":
{
...
},
"remarks" :
[
...
],
"links" :
[
...
],
"port43" : "whois.example.net",
"events" :
[
...
],
"entities" :
[
{
"objectClassName" : "entity",
"handle" : "XXXX-ABC",
"vcardArray":
[
...
],
"status" : [ "validated", "locked" ],
"roles" : [ "registrant" ],
"remarks" :
[
...
],
"links" :
[
...
],
"events" :
[
...
]
}
]
}
Figure 2
As described in Section 5 of RFC 7483 [RFC7483], RDAP responses can
contain "self" links. Service provider tags and self references
SHOULD be consistent. If they are inconsistent, the service provider
tag is processed with higher priority when using these values to
identify a service provider.
There is a risk of unpredictable processing behavior if the HYPHEN-
MINUS character is used for naturally occurring, non-separator
purposes in an entity handle. This could lead to a client mistakenly
assuming that a HYPHEN-MINUS character represents a separator and
that the text that follows HYPHEN-MINUS is a service provider
identifier. A client that queries the IANA registry for what they
assume is a valid service provider will likely receive an unexpected,
invalid result. As a consequence, use of the HYPHEN-MINUS character
as a service provider tag separator MUST be noted by adding an
rdapConformance value to query responses as described in Section 4.
The HYPHEN-MINUS character was chosen as a separator for two reasons:
1) it is a familiar separator character in operational use, and 2) it
avoids collision with URI-reserved characters. The list of
unreserved characters specified in Section 2.3 of RFC 3986 [RFC3986]
provided multiple options for consideration:
unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~"
ALPHA and DIGIT characters were excluded because they are commonly
used in entity handles for non-separator purposes. HYPHEN-MINUS is
commonly used as a separator, and recognition of this practice will
reduce implementation requirements and operational risk. The
remaining characters were excluded because they are not broadly used
as separators in entity handles.
3. Bootstrap Service Registry for Provider Object Tags
The bootstrap service registry for the RDAP service provider space is
represented using the structure specified in Section 3 of RFC 7484
[RFC7484]. The JSON output of this registry contains contact
information for the registered service provider identifiers,
alphanumeric identifiers that identify RDAP service providers, and
base RDAP service URLs as shown in this example.
{
"version": "1.0",
"publication": "YYYY-MM-DDTHH:MM:SSZ",
"description": "RDAP bootstrap file for service provider object tags",
"services": [
[
["contact@example.com"],
["YYYY"],
[
"https://example.com/rdap/"
]
],
[
["contact@example.org"],
["ZZ54"],
[
"http://rdap.example.org/"
]
],
[
["contact@example.net"],
["1754"],
[
"https://example.net/rdap/",
"http://example.net/rdap/"
]
]
]
}
Figure 3
Alphanumeric service provider identifiers conform to the suffix
portion ("\w{1,8}") of the "roidType" syntax specified in Section 4.2
of RFC 5730 [RFC5730].
3.1. Registration Procedure
The service provider registry is populated using the "First Come
First Served" policy defined in RFC 8126 [RFC8126]. Provider
identifier values can be derived and assigned by IANA on request.
Registration requests include an email address to be associated with
the registered service provider identifier, the requested service
provider identifier (or an indication that IANA should assign an
identifier), and one or more base RDAP URLs to be associated with the
service provider identifier.
4. RDAP Conformance
RDAP responses that contain values described in this document MUST
indicate conformance with this specification by including an
rdapConformance [RFC7483] value of "rdap_objectTag_level_0". The
information needed to register this value in the "RDAP Extensions"
registry is described in Section 5.2.
The following is an example rdapConformance structure with the
extension specified.
"rdapConformance" :
[
"rdap_level_0",
"rdap_objectTag_level_0"
]
Figure 4
5. IANA Considerations
IANA has created the RDAP "Bootstrap Service Registry for Provider
Object Tags" listed below and made it available as a JSON object.
The contents of this registry are described in Section 3; the formal
syntax is specified in Section 10 of RFC 7484 [RFC7484].
5.1. Bootstrap Service Registry Structure
Entries in this registry contain the following information:
o an email address that identifies a contact associated with the
registered RDAP service provider value.
o an alphanumeric value that identifies the RDAP service provider
being registered.
o one or more URLs that provide the RDAP service regarding this
registration. The URLs are expected to supply the same data, but
they can differ in scheme or other components as required by the
service operator.
5.2. RDAP Extensions Registry
IANA has registered the following value in the "RDAP Extensions"
registry:
Extension identifier: rdap_objectTag
Registry operator: Any
Published specification: This document
Contact: IESG <iesg@ietf.org>
Intended usage: This extension describes a best practice for
structuring entity identifiers to enable query bootstrapping.
6. Security Considerations
This practice uses IANA as a well-known, centrally trusted authority
to allow users to get RDAP data from an authoritative source, which
reduces the risk of sending queries to non-authoritative sources and
divulging query information to unintended parties. Using TLS 1.2
[RFC5246] or TLS 1.3 [RFC8446], which obsoletes TLS 1.2, to protect
the connection to IANA allows the server to authenticate itself as
being operated by IANA and provides integrity protection for the
resulting referral information, as well as provides privacy
protection via data confidentiality. The subsequent RDAP connection
is performed as usual and retains the same security properties of the
RDAP protocols themselves as described in RFC 7481 [RFC7481].
7. References
7.1. Normative References
[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>.
[RFC5730] Hollenbeck, S., "Extensible Provisioning Protocol (EPP)",
STD 69, RFC 5730, DOI 10.17487/RFC5730, August 2009,
<https://www.rfc-editor.org/info/rfc5730>.
[RFC7484] Blanchet, M., "Finding the Authoritative Registration Data
(RDAP) Service", RFC 7484, DOI 10.17487/RFC7484, March
2015, <https://www.rfc-editor.org/info/rfc7484>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[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>.
7.2. Informative References
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
<https://www.rfc-editor.org/info/rfc5246>.
[RFC7481] Hollenbeck, S. and N. Kong, "Security Services for the
Registration Data Access Protocol (RDAP)", RFC 7481,
DOI 10.17487/RFC7481, March 2015,
<https://www.rfc-editor.org/info/rfc7481>.
[RFC7482] Newton, A. and S. Hollenbeck, "Registration Data Access
Protocol (RDAP) Query Format", RFC 7482,
DOI 10.17487/RFC7482, March 2015,
<https://www.rfc-editor.org/info/rfc7482>.
[RFC7483] Newton, A. and S. Hollenbeck, "JSON Responses for the
Registration Data Access Protocol (RDAP)", RFC 7483,
DOI 10.17487/RFC7483, March 2015,
<https://www.rfc-editor.org/info/rfc7483>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
Acknowledgements
The authors would like to acknowledge the following individuals for
their contributions to the development of this document: Tom
Harrison, Patrick Mevzek, and Marcos Sanz. In addition, the authors
would like to recognize the Regional Internet Registry (RIR)
operators (AFRINIC, APNIC, ARIN, LACNIC, and RIPE) that have been
implementing and using the practice of tagging handle identifiers for
several years. Their experience provided significant inspiration for
the development of this document.
Authors' Addresses
Scott Hollenbeck
Verisign Labs
12061 Bluemont Way
Reston, VA 20190
United States of America
Email: shollenbeck@verisign.com
URI: http://www.verisignlabs.com/
Andrew Lee Newton
American Registry for Internet Numbers
PO Box 232290
Centreville, VA 20120
United States of America
Email: andy@arin.net
URI: http://www.arin.net
ISO Plain Language
On this page
§1Introduction
The Registration Data Access Protocol (RDAP) includes a method, described in RFC 7484, for identifying the authoritative server that handles domain name, IP address and Autonomous System Number (ASN) queries. The method works because each of those data elements is structured in a way that helps a client parse it and associate it with a particular RDAP service provider. Domain names, for example, include labels such as com, net and org that are associated with specific service providers.
As noted in Section 9 of RFC 7484, the method does not describe how to identify the authoritative server for entity queries, name server queries, help queries, or queries using certain search patterns. The reason is that the identifiers bound to those queries are not structured in a way that makes it easy to associate an identifier with a particular service provider.
This document describes an operational practice that adds structure to RDAP identifiers, so that the authoritative server can be identified for those additional queries as well.
When a client asks RDAP for a domain name or an address, the identifier itself says which registry holds the answer. When it asks about an organisation or a person, the identifier says nothing, so the client has no way to find the right server. This RFC gives those identifiers a small, structured ending so the client can find the server.
§2The Object Naming Practice
A service provider tag is constructed by prepending the Unicode HYPHEN-MINUS character, U+002D, which RFC 3986 describes as an unreserved character, to an IANA-registered value that represents the service provider. The tag for a service provider identified by the string value ARIN is written as -ARIN.
Together with the rdapConformance attribute described in Section 4, service provider tags are concatenated to the end of RDAP query object identifiers, so that the authoritative server for a query can be identified without doubt. An RDAP entity handle can then be built so that a client can bootstrap an entity query. The identifier XXXX-ARIN finds the information for the entity with handle XXXX at service provider ARIN.
A client parses this identifier into a handle and a service provider identifier. Handles can themselves contain hyphen characters, so the service provider identifier is whatever follows the last hyphen in the tagged identifier. The service provider identifier is used to retrieve a base RDAP URL from an IANA registry, and the base URL and the entity handle are then used to form a complete query path segment. If the base RDAP URL https://example.com/rdap/ is associated with service provider YYYY in an IANA registry, a client parses the tagged identifier XXXX-YYYY into the handle XXXX and the service provider YYYY, looks up the base URL, and forms the complete query URL https://example.com/rdap/entity/XXXX-YYYY.
The tag is a hyphen followed by a short code for the provider, for example -ARIN, and it goes at the end of the identifier. A client splits the identifier at its last hyphen, so the part before it is the handle and the part after it is the provider code. The provider code leads to a base address for the RDAP service, and the client adds the handle to build the final query address.
handle: XXXX
service tag: -YYYY
tagged id: XXXX-YYYY
base URL: https://example.com/rdap/
query URL: https://example.com/rdap/entity/XXXX-YYYY- Look up the provider codeThe client takes the text after the last hyphen and looks it up in the bootstrap registry.
- Base RDAP URLThe registry returns the service addresses registered for that provider code.
- RDAP queryThe client builds the query path from the base URL and the handle, and asks the authoritative server.
§2Tagged Handles in RDAP Responses
Putting the practice into use requires tagging the unstructured identifiers that appear in RDAP responses, because those are the identifiers a client may use in a later query. The RFC gives two examples of responses with tagged handles. In the first, the domain, the entity and the network all carry the handle XXXX-RIR, and the network names the parent handle YYYY-RIR. In the second, the domain handle is XXXX-YYY-DNR, the two name server handles are XXXX-DNR, and the entity handle is XXXX-ABC.
RDAP responses can contain self links, which point back at the object being returned. Service provider tags and self references should be consistent with each other. When they are not, the service provider tag is processed with higher priority when the values are used to identify a service provider.
The identifiers that come back in a response have to carry the tag too, because that is what a client will quote in its next query. A response may also contain a link back to itself, and that link and the tag should agree; when they do not, the tag wins.
§2The Risk of Hyphens and the Choice of Separator
There is a risk of unpredictable processing if the hyphen character is used for a natural, non-separator purpose inside an entity handle. A client could mistake such a hyphen for the separator and take the text that follows it to be a service provider identifier. A client that then queries the IANA registry for what it assumes is a valid service provider will likely get an unexpected, invalid result. For that reason, the use of the hyphen as a service provider tag separator must be noted by adding an rdapConformance value to query responses.
The hyphen was chosen as the separator for two reasons: it is a familiar separator character in operational use, and it avoids collision with URI-reserved characters. Section 2.3 of RFC 3986 lists several unreserved characters, namely ALPHA, DIGIT, hyphen, period, underscore and tilde. Letters and digits were excluded because they are commonly used in entity handles for non-separator purposes. The remaining characters were excluded because they are not broadly used as separators in entity handles.
Hyphens already appear inside many handles, so a client could misread part of a handle as a provider code. That is why the tag has to be declared in the response. The hyphen was picked because people already use it as a separator, and because it is one of the few characters that is safe in a web address.
- Tag formatA hyphen followed by the IANA-registered value for the provider.
- Split at the last hyphenHandles may contain hyphens, so the provider code is whatever follows the last one.
- Declare the tagA response using tagged identifiers lists rdap_objectTag_level_0 among its conformance values.
- Registry lookupThe provider code is looked up in the IANA bootstrap registry to get the base RDAP URL.
§3The Bootstrap Service Registry
The bootstrap service registry for the RDAP service provider space uses the structure specified in Section 3 of RFC 7484. Its JSON output holds contact information for the registered service provider identifiers, the alphanumeric identifiers themselves, and the base RDAP service URLs. Each entry lists a contact email address, the alphanumeric value that identifies the provider, and one or more URLs that provide the RDAP service for that registration. The URLs are expected to supply the same data, but they can differ in scheme or in other components as the service operator requires.
Service provider identifiers are alphanumeric and conform to the suffix portion, \w{1,8}, of the roidType syntax specified in Section 4.2 of RFC 5730.
The registry is populated under the First Come First Served policy of RFC 8126. Provider identifier values can be derived and assigned by IANA on request. A registration request includes an email address to associate with the registered identifier, the requested provider identifier, or an indication that IANA should assign one, and one or more base RDAP URLs to associate with it.
IANA keeps a registry that maps each provider code to the addresses of its RDAP service. A provider asks to be registered, giving a contact address, the code it wants, and its service addresses. Codes are handed out first come, first served, and follow a short alphanumeric format.
§4RDAP Conformance
RDAP responses that contain values described in this document must indicate conformance with this specification by including the rdapConformance value rdap_objectTag_level_0. The example given in the RFC is a list of conformance values that holds the base value and the new one:
"rdapConformance" :
[
"rdap_level_0",
"rdap_objectTag_level_0"
]A server that uses tagged identifiers says so in every response, by listing the value rdap_objectTag_level_0 among its conformance values. A client can then tell that the identifiers in that response carry a provider tag.
§5IANA Considerations
IANA has created the RDAP Bootstrap Service Registry for Provider Object Tags and made it available as a JSON object. The formal syntax is the one specified in Section 10 of RFC 7484. Each entry holds an email address for the contact associated with the registered value, the alphanumeric value identifying the RDAP service provider, and one or more URLs that provide the RDAP service for that registration.
IANA has also registered an extension in the RDAP Extensions registry: the extension identifier is rdap_objectTag, the registry operator is Any, the published specification is this document, and the contact is the IESG. Its intended usage is to describe a best practice for structuring entity identifiers so that queries can be bootstrapped.
IANA keeps two things for this practice: the JSON registry of provider codes and service addresses, and a registry entry recording that the rdap_objectTag extension describes the best practice.
§6Security Considerations
The practice uses IANA as a well-known, centrally trusted authority, so that users get RDAP data from an authoritative source. That reduces the risk of sending queries to non-authoritative sources and of divulging query information to unintended parties.
Using TLS 1.2 or TLS 1.3, which obsoletes TLS 1.2, to protect the connection to IANA lets the server authenticate itself as being operated by IANA and gives integrity protection for the referral information it returns, as well as privacy protection through data confidentiality. The RDAP connection that follows is performed as usual and keeps the security properties of the RDAP protocols themselves, described in RFC 7481.
Because the client reaches the right server through a registry run by IANA, it does not disclose its query to a random server. The connection to IANA must be protected with TLS, so that the client can check that it really is talking to IANA and that the referral has not been altered.