Authoritative DNS Transport Signaling
draft-johani-dnsop-transport-signaling-01
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draft-johani-dnsop-transport-signaling-01
DNSOP Working Group J. Stenstam
Internet-Draft L. Fernandez
Intended status: Standards Track E. Bergström
Expires: 25 December 2025 The Swedish Internet Foundation
23 June 2025
Authoritative DNS Transport Signaling
draft-johani-dnsop-transport-signaling-01
Abstract
This document proposes a mechanism for authoritative DNS servers to
opportunistically signal their support for alternative transport
protocols (e.g., DNS over TLS (DoT), DNS over HTTPS (DoH) and DNS
over QUIC (DoQ)) directly within the Additional section of
authoritative DNS responses. This "hint-based" approach aims to
enable resolvers to discover and upgrade transport connections more
efficiently, thereby improving privacy, security, and performance for
subsequent interactions.
The mechanism is designed to not require any protocol change. It is
safe, backward-compatible, and effective even when DNSSEC validation
of the hint is not possible or desired.
This document proposes an improvement on the opportunistic (but
blind) testing of alternative transports suggested in RFC9539 by
providing a mechanism by which a responding authoritative server may
signal what alternative transports it supports.
TO BE REMOVED: This document is being collaborated on in Github at:
https://github.com/johanix/draft-johani-dnsop-transport-signaling
(https://github.com/johanix/draft-johani-dnsop-transport-signaling).
The most recent working version of the document, open issues, etc,
should all be available there. The authors (gratefully) accept pull
requests.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
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Internet-Drafts are draft documents valid for a maximum of six months
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This Internet-Draft will expire on 25 December 2025.
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This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. 1. Introduction . . . . . . . . . . . . . . . . . . . . . . 3
1.1. 1.1. Prior Art . . . . . . . . . . . . . . . . . . . . . 3
1.2. Rationale for Using the Additional Section . . . . . . . 4
2. 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
3. 3. The Opportunistic Signaling Mechanism . . . . . . . . . . 5
4. 4. Authoritative Nameserver Behaviour . . . . . . . . . . . 5
4.1. 4.1. Trigger Conditions for Including the OTS Hint . . . 5
4.2. 4.2. Multiple Server Identities . . . . . . . . . . . . 6
4.3. 4.3. Format of the OTS Hint . . . . . . . . . . . . . . 6
5. 5. Recursive Nameserver Behavior . . . . . . . . . . . . . . 8
5.1. 5.1. When Sending Queries . . . . . . . . . . . . . . . 8
5.2. 5.2. When Receiving Responses . . . . . . . . . . . . . 8
5.3. 5.3. Authentication of the Authoritative Nameserver . . 9
5.4. 5.4. Resolver Caching Strategies . . . . . . . . . . . . 9
6. 6. The EDNS(0) No-OTS Option . . . . . . . . . . . . . . . . 11
7. 7. Comparison with DELEG . . . . . . . . . . . . . . . . . . 12
8. 8. Security Considerations . . . . . . . . . . . . . . . . . 12
9. 9. Operational Considerations . . . . . . . . . . . . . . . 13
10. 10. IANA Considerations . . . . . . . . . . . . . . . . . . 14
10.1. 10.1. No-OTS EDNS(0) Option . . . . . . . . . . . . . . 14
11. 11. Implementation Status . . . . . . . . . . . . . . . . . 14
12. 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . 14
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
13.1. Normative References . . . . . . . . . . . . . . . . . . 14
13.2. Informative References . . . . . . . . . . . . . . . . . 15
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Appendix A. Change History (to be removed before publication) . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. 1. Introduction
The Domain Name System (DNS) primarily relies on UDP and TCP for
communication between resolvers and authoritative servers. While
these protocols are well-established, there is a growing interest in
leveraging modern transport protocols like DNS over TLS (DoT)
[RFC7858], DNS over HTTPS (DoH) [RFC9461] and DNS over QUIC (DoQ)
[RFC9250] to enhance privacy, security, and performance.
Existing efforts to signal service connection information, such as
the SVCB and HTTPS DNS records [RFC9460] [RFC9461], primarily focus
on service discovery mechanisms where a client explicitly queries for
these records, often from a parent zone. While robust, this approach
can introduce additional latency and requires explicit configuration
at the parent zone level.
This document proposes an "DNS Opportunistic Transport Signaling"
(DNS OTS) mechanism. DNS OTS, aka an "OTS Hint" allows an
authoritative DNS nameserver to directly convey its transport
capabilities as a hint within the Additional section of responses to
queries where it identifies itself as an authoritative nameserver for
the requested zone. This direct, in-band signaling provides a low-
latency discovery path, even when a formal, validated signal is not
available. Furthermore, this is achieved without any changes to the
DNS Protocol.
1.1. 1.1. Prior Art
An attempt at utilizing more modern, and in particular, more private
transports between resolvers and authoritative nameservers was
introduced in [RFC9539]. The idea there was to opportunistically try
to send the query to the authoritative nameserver over multiple
transports with no prior knowledge of whether a transport was
supported in the receiving end or not.
The drawback with that approach is that without any significant
deployment of authoritative support the resolver end will mostly
spend cycles and traffic on a wasted effort. For this reason there
seems not to be any known implementations.
Furthermore, in Appendix B of [RFC9539] requirements for improving
the defense against an active attacker are listed. The first
requirement is:
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* A signaling mechanism that tells the recursive resolver that the
authoritative server intends to offer authenticated encryption.
This document aims to provide exactly such a mechanism while staying
within the current DNS protocol. Therefore the transport signaling
provided will be opportunistic, and as such fit well as an
improvement to [RFC9539].
1.2. Rationale for Using the Additional Section
*Note to the RFC Editor*: Please remove this entire section before
publication.
When designing a mechanism that rely on sending new information in
DNS responses without changing the current DNS protocol, the
Additional section has the major advantage of being ignored by legacy
software. This property makes it possible to essentially deploy the
proposed mechanism immediately, as it will not cause problems with
existing DNS infrastructure.
* Existing authoritative nameservers will not provide any OTS Hint
in the Additional section.
* Existing resolvers will actively ignore any OTS Hint in the
Additional section.
Only DNS nameservers (authoritative or recursive) that are aware of
the proposed mechanism will use it.
The downside is that it is not possible to strictly rely on anything
specific being present in the Additional section, as it may be
stripped off by a middle man or even by the sending nameserver (eg.
due to packet size constraints). For this reason it is not possible
to provide more than an opportunistic transport signal.
Another issue is whether the data provided may be trusted or not.
This is usually a major issue and the primary reason that data in the
Additional section is actively ignored by resolvers. In this
particular case, though, even an untrusted transport signal is better
than no signal at all. Furthermore, the only effect of a forged or
otherwise incorrect transport signal is a, typically failed,
connection attempt to an authoritative nameserver that does not
support the advertised transport. This will cause immediate fallback
to "Do53", i.e. traditional DNS over UDP/TCP and the non-availability
of the advertised transport will be remembered by the resolver (for
some suitable time).
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Hence, using the Additional section for opportunistic transport
signaling has vastly more benefits than drawbacks.
2. 2. Terminology
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.
* *Authoritative Nameserver (Auth Server):* A DNS server that holds
the authoritative zone data for a specific domain.
* *Recursive Nameserver (Resolver):* A DNS server that processes
user queries, performing iterative lookups to authoritative
servers to resolve domain names.
* *OTS Hint:* An SVCB record included opportunistically in the
Additional section of an authoritative DNS response, intended to
signal the responding authoritative nameserver's transport
capabilities.
* *SVCB Record:* Service Binding record, as defined in [RFC9460].
3. 3. The Opportunistic Signaling Mechanism
The core of this proposal is for an authoritative nameserver to
include an SVCB record in the Additional section of its responses
under specific conditions.
This consists of three parts. The first two are the behaviour of the
authoritative nameserver receiving the query and the rehaviour of the
recursive nameserver receiving the response. The final part is a new
EDNS(0) option that defines an OPT-OUT capability.
4. 4. Authoritative Nameserver Behaviour
4.1. 4.1. Trigger Conditions for Including the OTS Hint
An authoritative nameserver SHOULD include an OTS Hint when _all_ of
the following conditions are met:
1. *NS RRset Presence:* An NS Resource Record Set (RRset) for the
queried zone is present in either the Answer section or the
Authority section of the DNS response.
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2. *Self-Identification:* The responding authoritative nameserver's
own Fully Qualified Domain Name (FQDN) (or one of its configured
aliases/identities) is found within the NS RRset mentioned in
condition 1.
3. *Transport Capability:* The responding authoritative nameserver
supports one or more alternative transport protocols (e.g., DoT,
DoH, DoQ) and is configured to advertise these capabilities.
4. *Absence of the No-OTS Option:* The query does not include an
EDNS(0) No-OTS option from the resolver.
5. *Availability of RRSIG SVCB:* If the zone in which the nameserver
name is located is signed, only include the SVCB record if it is
possible to also include the corresponding RRSIG SVCB. If the
zone with the nameserver name is unsigned, then include the SVCB
even without the RRSIG.
4.2. 4.2. Multiple Server Identities
An authoritative nameserver may be known by multiple FQDNs (e.g.,
ns1.example.com, dns.customer.org, ns.cdnprovider.net). To
facilitate condition 2 ("Self-Identification"), authoritative server
implementations MAY include a configuration mechanism (e.g., an
identities list) where operators can list all FQDNs by which the
server is known. This allows the server to correctly identify itself
regardless of the specific name used in the NS RRset.
4.3. 4.3. Format of the OTS Hint
The OTS Hint MUST be an SVCB record with the following
characteristics:
* *OWNER:* The owner name of the SVCB record MUST be the FQDN of the
authoritative nameserver itself, as identified in the NS RRset
that triggered its inclusion (e.g., ns.dnsprovider.com.).
* *CLASS:* IN (Internet).
* *TYPE:* SVCB.
* *TTL:* The TTL of the SVCB record SHOULD be chosen by the
authoritative server operator. Choice of TTL is a local
configuration decision, but unless the supported transports are
subject to frequent change a value on the order of 24h or more is
suggested.
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* *SVCB_PRIORITY:* 1. The specific priority value is not critical
for this hint mechanism, but 1 indicates the highest priority for
the service.
* *SVCB_TARGET:* . (root). This indicates that the DNS transport
capabilities described by the SVCB record refer to the owner name
of the record.
* *SVCB_PARAMS:* A set of Service Parameters indicating the
supported transport protocols. In this document only the "alpn"
parameter [RFC9460] is defined, as relevant for signaling DoT
(alpn=dot), DoH (alpn=doh) and DoQ (alpn=doq).
If any other parameter, including "ipv4hint" and "ipv6hint", is
present in the SVCB parameter list then it SHOULD be ignored.
*Example 1:*
If ns.dnsprovider.net. responds to a query for www.example.com. and
ns.dnsprovider.net is listed in the NS RRset, it may respond with a
DNS message that contains: ~~~ Header: ...
Answer: www.example.com. IN A 1.2.3.4
Authority: example.com. IN NS ns1.example.com. example.com. IN NS
ns.dnsprovider.net.
Additional: ns.dnsprovider.net. IN A 5.6.7.8 ns.dnsprovider.net. IN
RRSIG A ... ns.dnsprovider.net. IN SVCB 1 . "alpn=doq,dot,do53"
ns.dnsprovider.net. IN RRSIG SVCB ... ~~~ *Example 2:*
If the unsigned zone example.com uses ns.dnsprovider.net., but under
the vanity name "ns2.example.com." (with the same IP addresses), then
a possible response from ns.dnsprovider.net (aka ns2.example.com) may
be: ~~~ Header: ...
Answer: www.example.com. IN A 1.2.3.4
Authority: example.com. IN NS ns1.example.com. example.com. IN NS
ns2.example.com.
Additional: ns2.example.com. IN A 5.6.7.8 ns2.example.com. IN SVCB
1 . "alpn=doq,dot,do53" ~~~ This requires that "ns2.example.com." is
a name that ns.dnsprovider.net. is aware of as one of its identities.
Furthermore, as the zone example.com is unsigned it is not possible
to provide a DNSSEC signed OTS Hint in the second example.
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5. 5. Recursive Nameserver Behavior
Recursive nameservers adopting this mechanism SHOULD implement the
following logic:
5.1. 5.1. When Sending Queries
1. *OPT-OUT Possibility:* If the resolver already thinks that it
knows the transport capabilities of the authoritative nameserver
it is about to send a query to it may opt out from DNS transport
signaling by including an EDNS(0) "No-OTS" option in the query.
5.2. 5.2. When Receiving Responses
1. *Opportunistic Parsing:* When receiving an authoritative DNS
response, the resolver SHOULD parse the Additional section for
SVCB records.
2. *Owner Check:* If an SVCB record is found whose owner name
matches an authoritative nameserver identified in the Authority
or Answer sections of the _current_ response, the resolver MAY
consider this an OTS Hint.
3. *DNSSEC Validation (Optional but Recommended):* * The resolver
SHOULD attempt to DNSSEC validate the OTS Hint. This involves
validating the SVCB record itself and its corresponding RRSIG (if
present) against the DNSSEC chain of trust for the zone that owns
the SVCB record (e.g., dnsprovider.com for ns.dnsprovider.com).
* If validation succeeds: The OTS Hint is considered a *trusted
signal*. The resolver MAY then prefer the signaled alternative
transports for subsequent queries to that specific authoritative
nameserver.
* If validation fails, or no RRSIG is present: The OTS Hint MUST be
treated as an *unvalidated hint*. The resolver MAY still
opportunistically attempt to use the signaled alternative
transports, but MUST be prepared for immediate fallback to
traditional transports (UDP/TCP) if the connection fails. This is
particularly relevant for scenarios like vanity names (e.g.,
ns.customer.com where customer.com is an unsigned zone, but the
underlying server ns.dnsprovider.com is capable).
1. *Prioritization:* * Any DNSSEC-validated SVCB record found via
explicit query (e.g., ns.example.com for a queried domain MUST
take precedence over any unvalidated OTS Hint.
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* The OTS Hint is a mechanism to _discover_ capabilities
opportunistically, not to override trusted delegation or service
configuration.
1. Fallback: Resolvers MUST always be prepared to fall back to
traditional UDP/TCP transport if an attempt to use an alternative
transport based on an OTS Hint (especially an unvalidated one)
fails or times out.
5.3. 5.3. Authentication of the Authoritative Nameserver
Authentication of the authoritative nameserver is not an explicit
goal. The reason is that as an opportunistic mechanism it will not
always be possible to do such authentication. Some of the options
that do exist are listed below.
Authentication of the authoritative nameserver may be done either by
validation of a DNSSEC RRSIG over the SVCB record containing the OTS
Hint or by verification of the server certificate presented in the
set up of the communication (be it over DoT, DoQ or DoH).
As there will not always be a DNSSEC signature to validate that
option is opportunistic at best. Likewise, while it may sometimes be
possible to validate the server cert against a DNSSEC-signed TLSA
record, it will not always be an option.
Finally, validating the server cert against a list of well-known
public Certificate Authorities is possible, but there is no
standardized way to determine which CAs are appropriate for DNS
server certificates.
However, even without strong authentication of the authoritative
server the proposed mechanism still provides benefits (privacy,
potential performance improvements) and for that reason cryptographic
verification of the server identity is not a requirement.
5.4. 5.4. Resolver Caching Strategies
Resolvers implementing the DNS OTS Hint mechanism have several
options for caching the transport signals received via OTS Hints.
A suggested primary strategy is to set the EDNS(0) No-OTS option when
no transport signaling information is needed (because the resolver
already knows the authoritative nameservers transport capabilities
from a previous response or for some other reason).
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Three example caching strategies are listed below. Other strategies
are possible. Each strategy has different trade-offs in terms of
efficiency, responsiveness to changes, and resource usage:
1. *Standard DNS Cache:* Treat the SVCB record like any other DNS
record, caching it according to its TTL. This is the simplest
approach and will simply cause the resolver to fall back to UDP
for one query if the transport signal data has expired.
2. *Cache-Until-Fail:* Cache the transport signal until a connection
attempt fails, then invalidate the cached entry. This approach
uses more aggressive caching based on the assumption that changes
to transport capabilites are expected to be rare, and there is no
risk of presenting any data that is no longer correct. The
possible downside is that the resolver will not learn about
possible new transports that become available. E.g., with an
"alpn=doq", the resolver will not learn that the authoritative
server later started to support DNS-over-TLS (in addition to DoQ)
if it is successfully using the DNS-over-QUIC connection.
3. *Success-Based Refresh:* Refresh the transport signal cache entry
each time a successful connection is made using that transport.
This provides a balance between efficiency and responsiveness but
requires additional bookkeeping.
For a more detailed analysis of possible caching logic, see
[RFC9539], section 4.
Note that the resolver always has the option of not using the EDNS(0)
No-OTS option whenever the cache entry is getting close to expiry.
Given the variety of deployment scenarios and operational
requirements, this document does not mandate a specific caching
strategy. Implementers SHOULD choose a strategy that best fits their
operational needs, considering factors such as:
* The importance of minimizing connection attempts
* The impact of failed connection attempts
* The computational cost of different caching strategies
* The memory requirements of maintaining cache state
The chosen strategy SHOULD be documented in the implementation's
configuration options to allow operators to make informed decisions
about its use.
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6. 6. The EDNS(0) No-OTS Option
To provide a mechanism for resolvers to explicitly opt out of
receiving transport signals, this document defines a new EDNS(0)
option called "No-OTS" (NOTS). When included in a query, this option
signals to the authoritative server that the resolver does not want
to receive any transport signals in the response.
The typical use case is to set the EDNS(0) No-OTS option when the
resolver already has the transport information it needs.
The EDNS(0) No-OTS option is structured as follows:
1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
0: | OPTION-CODE |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
2: | OPTION-LENGTH |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
Field definition details:
OPTION-CODE: 2 octets / 16 bits (defined in [RFC6891]) contains the
value TBD for No-OTS.
OPTION-LENGTH: 2 octets / 16 bits (defined in [RFC6891]) contains the
length of the payload in octets. For the No-OTS option, this value
MUST be 0 as there is no payload.
When an authoritative server receives a query containing the EDNS(0)
No-OTS option, it SHOULD NOT include any OTS Hints in the response,
regardless of whether it would normally do so based on the conditions
described in Section 3.1.
This option provides a clean way for resolvers to opt out of
receiving transport signals, which may be useful in scenarios where:
* The resolver has already established transport preferences for a
particular authoritative server
* The resolver does not support or does not want to use alternative
transports
* The resolver wants to minimize response sizes
* The resolver is operating in an environment where transport
signals are not needed or desired
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The No-OTS option is designed to be a simple, lightweight mechanism
that can be used to disable transport signaling without affecting the
normal operation of DNS resolution.
7. 7. Comparison with DELEG
The idea to use an SVCB alpn parameter for transport signaling
originated with the work on DELEG [I-D.draft-ietf-deleg]. The
current document uses the same data format, but as an opportunistic
addition to the Additional section rather than as integral part of a
changed delegation mechanism.
Both mechanisms have distinct use cases, and pros and cons. The
major advantage of the DELEG mechanism is that it cannot be spoofed
or filtered, as it is an integral part of an upcoming protocol
change.
The opportunistic mechanism described here has the major advantage of
being available immediately without any changes to the DNS protocol.
Furthermore, as it is a signal directly from an authoritative
nameserver, a single OTS Hint may allow the recipient recursive
nameserver to upgrade the transport used for all the zones served by
that authoritative nameserver (which may be millions) without the
need to make any changes to the zones, nor to the parent zones.
Given the current DNS landscape with a limited number of very large
providers of authoritative DNS service and a limited number of large
providers of recursive DNS service the opportunistic model described
here has the potential of enabling upgrading the transport for a
significant fraction of the DNS traffic with a limited amount of
effort.
8. 8. Security Considerations
* *Spoofing of Unvalidated Hints:* An OTS Hint that cannot be DNSSEC
validated (e.g., for ns.example.com where example.com is unsigned)
is susceptible to spoofing by an on-path attacker. Such an
attacker could insert a fake SVCB record advertising a non-
existing transport, thereby denying connection over that
transport. However, since the hint is opportunistic and not
required for DNS resolution, the worst-case scenario is that the
resolver attempts a connection that fails and then falls back to
traditional transports. Security for the actual DNS data remains
unaffected. The cryptographic validation of TLS/QUIC (via X.509
certificates) for DoT/DoQ would still protect the integrity and
privacy of the connection itself.
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* *DNSSEC Validation:* When a OTS Hint is signed by DNSSEC (e.g.,
the ns.dnsprovider.net SVCB record from a signed dnsprovider.net
zone), it provides a trusted signal. Resolvers SHOULD leverage
DNSSEC validation to distinguish between trusted and unvalidated
hints.
* *No New Attack Vectors:* This mechanism does not introduce new
attack vectors for DNS data itself, as it primarily concerns
transport discovery. It relies on the existing security
properties of DoT, DoH and DoQ for actual session security.
* *Safe Rollout:* As existing recursive nameservers carefully avoid
data in the Additional section that they do not need, the OTS Hint
will be ignored by everyone except recursive nameservers that
understand the OTS Hint.
* *No-OTS enables a downgrade attack:* If an attacker is able to
inject a No-OTS option to an outbound query then no transport
signal will be provided. However, this is a consequence of the
opportunistic nature of the OTS Hint and not worse than not being
able to do transport signaling at all.
9. 9. Operational Considerations
* *Response Size:* Including an SVCB record in the Additional
section will increase the size of UDP responses. Authoritative
server operators should consider the potential for UDP
fragmentation or TCP fallback if responses become excessively
large, though a single SVCB record is typically small. Recursive
nameservers should usually set the EDNS(0) No-OTS when they
already have the transport signaling information.
* *Server Configuration:* Authoritative server implementations will
need configuration options to enable this feature and manage the
identities list.
* *Rollout Strategy:* This mechanism supports a gradual rollout.
Authoritative servers can begin sending hints without requiring
changes from resolvers, and resolvers can begin processing hints
without requiring all authoritative servers to implement the
feature.
* *Monitoring:* As there is extremely limited data on effects of
alternative DNS transports for communication resolver to
authoritative nameserver it is strongly suggested that monitoring
(of use, resource consumption, etc) is considered.
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10. 10. IANA Considerations
10.1. 10.1. No-OTS EDNS(0) Option
This document defines a new EDNS(0) option, entitled "No-OTS",
assigned a value of TBD in the "DNS EDNS0 Option Codes (OPT)"
registry.
+-------+--------------------------+----------+----------------------+
| Value | Name | Status | Reference |
+-------+--------------------------+----------+----------------------+
| TBD | No-OTS | Standard | ( This document ) |
+-------+--------------------------+----------+----------------------+
*Note to the RFC Editor*: In this section, please replace occurrences
of "(This document)" with a proper reference.
11. 11. Implementation Status
*Note to the RFC Editor*: Please remove this entire section before
publication.
The TDNS Framework of experimental DNS servers developed and
maintained by the Swedish Internet Foundation implements this draft
(see https://github.com/johanix/tdns (https://github.com/johanix/
tdns)). TDNS has support for both the authoritative nameserver and
recursive nameserver parts of the draft.
12. 12. Acknowledgments
* The participants of the DELEG Working Group, Peter Thomassen and
Christian Elmerot.
13. References
13.1. 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/rfc/rfc2119>.
[RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms
for DNS (EDNS(0))", STD 75, RFC 6891,
DOI 10.17487/RFC6891, April 2013,
<https://www.rfc-editor.org/rfc/rfc6891>.
Stenstam, et al. Expires 25 December 2025 [Page 14]
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[RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D.,
and P. Hoffman, "Specification for DNS over Transport
Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May
2016, <https://www.rfc-editor.org/rfc/rfc7858>.
[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/rfc/rfc8174>.
[RFC9250] Huitema, C., Dickinson, S., and A. Mankin, "DNS over
Dedicated QUIC Connections", RFC 9250,
DOI 10.17487/RFC9250, May 2022,
<https://www.rfc-editor.org/rfc/rfc9250>.
[RFC9460] Schwartz, B., Bishop, M., and E. Nygren, "Service Binding
and Parameter Specification via the DNS (SVCB and HTTPS
Resource Records)", RFC 9460, DOI 10.17487/RFC9460,
November 2023, <https://www.rfc-editor.org/rfc/rfc9460>.
[RFC9461] Schwartz, B., "Service Binding Mapping for DNS Servers",
RFC 9461, DOI 10.17487/RFC9461, November 2023,
<https://www.rfc-editor.org/rfc/rfc9461>.
[RFC9539] Gillmor, D. K., Ed., Salazar, J., Ed., and P. Hoffman,
Ed., "Unilateral Opportunistic Deployment of Encrypted
Recursive-to-Authoritative DNS", RFC 9539,
DOI 10.17487/RFC9539, February 2024,
<https://www.rfc-editor.org/rfc/rfc9539>.
13.2. Informative References
[I-D.draft-ietf-deleg]
April, T., Špaček, P., Weber, R., and Lawrence,
"Extensible Delegation for DNS", Work in Progress,
Internet-Draft, draft-ietf-deleg-00, 6 May 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-deleg-
00>.
Appendix A. Change History (to be removed before publication)
Initial public draft
Authors' Addresses
Johan Stenstam
The Swedish Internet Foundation
Sweden
Email: johan.stenstam@internetstiftelsen.se
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Leon Fernandez
The Swedish Internet Foundation
Sweden
Email: leon.fernandez@internetstiftelsen.se
Erik Bergström
The Swedish Internet Foundation
Sweden
Email: erik.bergstrom@internetstiftelsen.se
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