Hi Sarah, On 9/16/25 15:45, Sarah Tarrant wrote:
Hi Martine,Thank you for your reply! A) Regarding:* Are the References, Authors' Addresses, Contributors, and Acknowledgments sections current?For the most part, yes. However, there was a last minute typo found by Jan Romann, so we’d like to add him to the list of thanks in our acknowledgements. We have a change prepared for that in the working group repo [1], however, not as a draft version. Should we just submit that as a version now, or wait until AUTH48 for minor changes like that?Please submit a new version to datatracker so that it's clear where that change originated.
See https://datatracker.ietf.org/doc/draft-ietf-core-dns-over-coap/20/
B) Also, regarding "Regarding specific RFC numbers," - we have made a note of your request and will see if we can make it happen! After submitting the new draft to datatracker, please send along the self-contained markdown file to us so we can get started.
Find attached. Best Martine
Sincerely, Sarah Tarrant RFC PRoduction CenterOn Sep 16, 2025, at 5:49 AM, Martine Sophie Lenders <martine.lend...@tu-dresden.de> wrote: Dear Sarah, Find our reply to your questions inline. On 9/11/25 23:33, Sarah Tarrant wrote:[...] 1) As there may have been multiple updates made to the document during Last Call, please review the current version of the document: * Is the text in the Abstract is still accurate?Yes.* Are the References, Authors' Addresses, Contributors, and Acknowledgments sections current?For the most part, yes. However, there was a last minute typo found by Jan Romann, so we’d like to add him to the list of thanks in our acknowledgements. We have a change prepared for that in the working group repo [1], however, not as a draft version. Should we just submit that as a version now, or wait until AUTH48 for minor changes like that? [1] https://github.com/core-wg/draft-dns-over-coap/commit/bf41ba46e2f211956cc11347ef3ce247db4802162) Please share any style information that could help us with editing your document. For example: * Is your document's format or its terminology based on another document? If so, please provide a pointer to that document (e.g., this document's terminology should match DNS terminology in RFC 9499).All documents we derive terminology from are referenced in Section 2, “Terminology and Conventions”.* Is there a pattern of capitalization or formatting of terms? (e.g., field names should have initial capitalization; parameter names should be in double quotes; <tt/> should be used for token names; etc.)Please refer to the respective CoAP and DNS specification for most of that. In general, we - Put hex dumps and examples in <tt/> (e.g., <tt>ff 0a 00 04 03 64 6e 73</tt>), - Put text strings occuring, e.g., in the format or IANA tables, as well as the name of SvcParamKeys in quotation marks (e.g., "application/dns-message", "coaps://[2001:db8::1]/", "alpn", …), - Wrote DNS header fields, record type, and classes in ALLCAPS, - Capitalized CoAP options (e.g., Uri-Path, Content-Format, …), and - Protocol names and other proper names are capitalized. Examples are represented as code blocks, the human-readable parts are loosely based on the output of the dig tool.3) Is there any text that should be handled extra cautiously? For example, are there any sections that were contentious when the document was drafted?There were no particularly contentious sections. However, Section 5.1 "DNS Push Notifications and CoAP Observe" and Section 10 "Operational Considerations" were quite heavily reworked (or in case of Section 10, specifically created) during the IESG review stage. As they did not receive as many eyeballs yet, they should receive extra attention.4) Is there anything else that the RPC should be aware of while editing this document?No.5) This document uses one or more of the following text styles. Are these elements used consistently? * fixed width font (<tt/> or `) * italics (<em/> or *) * bold (<strong/> or **)Yes.6) This document is part of Cluster 554. * To help the reader understand the content of the cluster, is there a document in the cluster that should be read first? Next? If so, please provide the order and we will provide RFC numbers for the documents accordingly. If order is not important, please let us know.draft-ietf-core-coap-dtls-alpn is a normative reference for draft-ietf-core-dns-over-coap: The ALPN ID defined in draft-ietf-core-coap-dtls-alpn is used for the discovery of DNS over CoAP servers in draft-ietf-core-dns-over-coap. This is the main reason why these documents are clustered. As such, draft-ietf-core-coap-dtls-alpn should be read first. We do not have any preferred order, in our eyes they do not even need to sit right next to each other. Regarding specific RFC numbers, our co-author Christian Amsüss already contacted rfc-edi...@rfc-editor.org on Sep 11th: If that is something that can be requested at all, we would love to have a number that ends in -53 (referencing the DNS port number) or -84 (referencing the RFC8484/DoH legacy) as a little easter egg for draft-ietf-core-dns-over-coap. However, we do see this as nothing more than an easter egg, so if that is not possible or would delay publication too much, we are fine with any number.* Is there any text that has been repeated within the cluster document that should be edited in the same way? For instance, parallel introductory text or Security Considerations.No.7) Would you like to participate in the RPC Pilot Test for editing in kramdown-rfc? If so, please let us know and provide a self-contained kramdown-rfc file. For more information about this experiment, see: https://www.rfc-editor.org/rpc/wiki/doku.php?id=pilot_test_kramdown_rfc.Since we edited the draft originally in kramdown-rfc, yes. Kind regards, Martine Lenders on behalf of all co-authorsOn Sep 11, 2025, at 4:29 PM, rfc-edi...@rfc-editor.org wrote: Author(s), Your document draft-ietf-core-dns-over-coap-19, which has been approved for publication as an RFC, has been added to the RFC Editor queue <https://www.rfc-editor.org/current_queue.php>. If your XML file was submitted using the I-D submission tool <https://datatracker.ietf.org/submit/>, we have already retrieved it and have started working on it. If you did not submit the file via the I-D submission tool, or if you have an updated version (e.g., updated contact information), please send us the file at this time by attaching it in your reply to this message and specifying any differences between the approved I-D and the file that you are providing. You will receive a separate message from us asking for style input. Please respond to that message. When we have received your response, your document will then move through the queue. The first step that we take as your document moves through the queue is converting it to RFCXML (if it is not already in RFCXML) and applying the formatting steps listed at <https://www.rfc-editor.org/pubprocess/how-we-update/>. Next, we will edit for clarity and apply the style guide (<https://www.rfc-editor.org/styleguide/>). You can check the status of your document at <https://www.rfc-editor.org/current_queue.php>. You will receive automatic notifications as your document changes queue state (for more information about these states, please see <https://www.rfc-editor.org/about/queue/>). When we have completed our edits, we will move your document to AUTH48 state and ask you to perform a final review of the document. Please let us know if you have any questions. Thank you. The RFC Editor Team
---
v: 3
title: "DNS over CoAP (DoC)"
abbrev: DoC
docname: draft-ietf-core-dns-over-coap-20
category: std
submissiontype: IETF
v3xml2rfc:
silence:
- Found SVG with width or height specified
area: Applications
workgroup: CoRE
keyword:
- Internet-Draft
- CoRE
- CoAP
- DNS
venue:
group: CoRE
type: Working Group
mail: c...@ietf.org
arch: "https://mailarchive.ietf.org/arch/browse/core/";
github: "core-wg/draft-dns-over-coap"
latest: "https://core-wg.github.io/draft-dns-over-coap/draft-ietf-core-dns-over-coap.html";
author:
- name: Martine Sophie Lenders
org: TUD Dresden University of Technology
abbrev: TU Dresden
street: Helmholtzstr. 10
city: Dresden
code: D-01069
country: Germany
email: martine.lend...@tu-dresden.de
- name: Christian Amsüss
email: christ...@amsuess.com
- name: Cenk Gündoğan
org: NeuralAgent GmbH
street: Mies-van-der-Rohe-Straße 6
city: Munich
code: D-80807
country: Germany
email: cenk.gundo...@neuralagent.ai
- name: Thomas C. Schmidt
org: HAW Hamburg
street: Berliner Tor 7
city: Hamburg
code: D-20099
country: Germany
email: t.schm...@haw-hamburg.de
- name: Matthias Wählisch
org: TUD Dresden University of Technology & Barkhausen Institut
abbrev: TU Dresden & Barkhausen Institut
street: Helmholtzstr. 10
city: Dresden
code: D-01069
country: Germany
email: m.waehli...@tu-dresden.de
normative:
STD13: dns
RFC3986: uri
RFC5234: abnf
RFC6347: dtls12
RFC7252: coap
RFC7641: coap-observe
RFC7959: coap-blockwise
RFC8132: coap-fetch
RFC8323: coap-tcp
RFC8484: doh
RFC8613: oscore
RFC8765: dns-push
RFC8768: coap-hop-limit
RFC8949: cbor
RFC9147: dtls13
RFC9460: svcb
RFC9461: svcb-dns
RFC9462: ddr
RFC9463: dnr
I-D.ietf-core-coap-dtls-alpn: coap-dtls-alpn
informative:
BCP219: dns-terminology
BCP237: dnssec
RFC3833: dns-threats
RFC6690: core-link-format
RFC7228: constr-nodes
RFC7858: dot
RFC8094: dodtls
RFC9076: dns-privacy
RFC9176: core-rd
RFC9250: doq
RFC9528: edhoc
I-D.ietf-core-href: cri
I-D.ietf-core-transport-indication: transport-indication
I-D.ietf-iotops-7228bis: constr-nodes-bis
I-D.amsuess-core-cachable-oscore: cachable-oscore
DoC-paper: DOI.10.1145/3609423
I-D.ietf-core-corr-clar: core-corrclar
REST:
target: https://www.ics.uci.edu/~fielding/pubs/dissertation/fielding_dissertation.pdf
title: Architectural Styles and the Design of Network-based Software Architectures
author:
ins: R. Fielding
name: Roy Thomas Fielding
org: University of California, Irvine
date: 2000
seriesinfo:
"Ph.D.": "Dissertation, University of California, Irvine"
format:
HTML: https://ics.uci.edu/~fielding/pubs/dissertation/top.htm
PDF: https://www.ics.uci.edu/~fielding/pubs/dissertation/fielding_dissertation.pdf
--- abstract
This document defines a protocol for exchanging DNS queries (OPCODE 0) over the
Constrained Application Protocol (CoAP). These CoAP messages can be protected
by (D)TLS-Secured CoAP (CoAPS) or Object Security for Constrained RESTful
Environments (OSCORE) to provide encrypted DNS message exchange for
constrained devices in the Internet of Things (IoT).
--- middle
Introduction
============
This document defines DNS over CoAP (DoC), a protocol to send DNS
{{-dns}} queries and get DNS responses over the Constrained Application
Protocol (CoAP) {{-coap}} using OPCODE 0 (Query). Each DNS query-response pair is mapped into a
CoAP message exchange. Each CoAP message can be secured by DTLS 1.2 or newer {{-dtls12}} {{-dtls13}}
as well as Object Security for Constrained RESTful Environments (OSCORE) {{-oscore}}
but also TLS 1.3 or newer {{-coap-tcp}} {{?RFC8446}}
to ensure message integrity and confidentiality.
The application use case of DoC is inspired by DNS over HTTPS {{-doh}}
(DoH). DoC, however, aims for deployment in the constrained Internet of
Things (IoT), which usually conflicts with the requirements introduced by
HTTPS.
Constrained IoT devices may be restricted in memory, power consumption,
link-layer frame sizes, throughput, and latency. They may
only have a handful kilobytes of both RAM and ROM. They may sleep for long
durations of time, after which they need to refresh the named resources they
know about. Name resolution in such scenarios must take into account link
layer frame sizes of only a few hundred bytes, bit rates in the magnitude
of kilobits per second, and latencies of several seconds {{-constr-nodes}} {{-constr-nodes-bis}} [^remove-constr-nodes].
[^remove-constr-nodes]: RFC Ed.: Please remove the {{-constr-nodes}} reference and replace it with {{-constr-nodes-bis}} throughout the document in case {{-constr-nodes-bis}} becomes an RFC before publication.
In order not to be burdened by the resource requirements of TCP and HTTPS, constrained IoT devices could use DNS over DTLS {{-dodtls}}.
In contrast to DNS over DTLS, DoC
can take advantage of CoAP features to mitigate drawbacks of datagram-based
communication. These features include: block-wise transfer {{-coap-blockwise}}, which solves
the Path MTU problem of DNS over DTLS (see {{-dodtls, Section 5}}); CoAP
proxies, which provide an additional level of caching; re-use of data
structures for application traffic and DNS information, which saves memory
on constrained devices.
To avoid the resource requirements of DTLS or TLS on top of UDP (e.g., introduced by DNS over DTLS {{-dodtls}} or DNS over QUIC {{-doq}}), DoC allows for lightweight message protection based on OSCORE.
~~~ aasvg
. FETCH coaps://[2001:db8::1]/
/
/
CoAP request
+------+ [DNS query] +------+------+ DNS query .---------------.
| DoC |---------------->| DoC | DNS |--- --- --- --->| DNS |
|Client|<----------------|Server|Client|<--- --- --- ---| Infrastructure |
+------+ CoAP response +------+------+ DNS response '---------------'
[DNS response]
\ / \ /
'------DNS over CoAP------' '----DNS over UDP/HTTPS/QUIC/...----'
~~~
{: #fig-overview-arch title="Basic DoC architecture"}
The most important components of DoC can be seen in {{fig-overview-arch}}: a DoC
client tries to resolve DNS information by sending DNS queries carried within
CoAP requests to a DoC server.
That DoC server can be the authoritive name server for the queried record or a DNS client (i.e., a stub or recursive resolver) that resolves DNS information by using other DNS transports such
as DNS over UDP {{-dns}}, DNS over HTTPS {{-doh}}, or DNS over QUIC {{-doq}} when communicating with the upstream
DNS infrastructure.
Using that information, the DoC server then replies to the queries of the DoC client with DNS
responses carried within CoAP responses.
A DoC server MAY also serve as DNSSEC validator to provide DNSSEC validation to the more
constrained DoC clients.
Note that this specification is distinct from DoH, since the CoAP-specific FETCH method {{-coap-fetch}} is used.
This has the benefit of having the DNS query in the body as when using the POST method, but still with the same caching advantages of responses to requests that use the GET method.
Having the DNS query in the body means that we do not need extra base64 encoding, which would increase
code complexity and message sizes.
Also, this allows for the block-wise transfer of queries {{-coap-blockwise}}.
Terminology and Conventions
===========================
{::boilerplate bcp14-tagged}
A server that provides the service specified in this document is called a "DoC
server" to differentiate it from a classic "DNS server".
A DoC server acts either as a DNS stub resolver or a DNS recursive resolver {{-dns-terminology}}.
As such, the DoC server communicates with an "upstream DNS infrastructure" or a single "upstream DNS server".
A "DoC resource" is a CoAP resource {{-coap}} at the DoC server that DoC clients can target to send a DNS query in a CoAP request.
A client using the service specified in this document to retrieve the
DNS information is called a "DoC client".
The term "constrained nodes" is used as defined in {{-constr-nodes}}.
{{-core-link-format}} describes that "Constrained RESTful Environments (CoRE)" realize the Representational State Transfer (REST) architecture {{REST}} in a suitable form for such constrained nodes.
A DoC server can provide Observe capabilities as defined in {{-coap-observe, Section 1.2}}.
As part of that, it administers a "list of observers".
DoC clients using these capabilities are "observers" as defined in {{-coap-observe, Section 1.2}} in that case.
A "notification" is a CoAP response message with an Observe option, see {{-coap-observe, Section 4.2}}.
The terms "payload" and "body" are used as defined in {{-coap-blockwise, Section 2}}.
Note that, when block-wise transfer is not used, the terms "payload" and "body" are to be understood as equal.
For better readability, in the examples in this document the binary payload and resource records are shown in a hexadecimal representation as well as a human-readable format.
In the actual message sent and received, however, they are encoded in the binary message format defined in {{-dns}}.
Selection of a DoC Server {#sec:doc-server-selection}
=========================
While there is no path specified for the DoC resource, it is RECOMMENDED to use the root path "/"
to keep the CoAP requests small.
The DoC client needs to know the DoC server and the DoC resource at the DoC server.
Possible options to assure this could be manual configuration of a Uniform Resource Identifier (URI) {{-uri}} or Constrained Resource Identifier (CRI) {{-cri}},
or automatic configuration, e.g., using a CoRE resource directory
{{-core-rd}}, DHCP or Router Advertisement options {{-dnr}}, or discovery of designated resolvers
{{-ddr}}.
Automatic configuration MUST only be done from a trusted source.
## Discovery by Resource Type
For discovery of the DoC resource through a link mechanism that allows describing a resource type
(e.g., the Resource Type attribute in {{-core-link-format}}), this document introduces the resource type "core.dns".
It can be used to identify a generic DNS resolver that is available to the client.
## Discovery using SVCB Resource Records or DNR
A DoC server can also be discovered using Service Binding (SVCB) Resource Records (RR) {{-svcb}} {{-svcb-dns}} resolved via another DNS service (e.g., provided by an unencrypted local resolver) or Discovery of Network-designated Resolvers (DNR)
Service Parameters {{-dnr}} via DHCP or Router Advertisements.
{{-coap-tcp}} defines the Application-Layer Protocol Negotiation (ALPN) ID for CoAP over TLS servers and {{-coap-dtls-alpn}} defines the ALPN ID for CoAP over DTLS servers.
DoC servers that use only OSCORE {{-oscore}} and Ephemeral Diffie-Hellman Over COSE (EDHOC) {{-edhoc}} (with COSE abbreviating "Concise Binary Object Notation (CBOR) Object Signing and Encryption" {{?RFC9052}}) to support security cannot be discovered using these SVCB RR or DNR mechanisms.
Specifying an alternate discovery mechanism is out of scope of this document.
This document is not an SVCB mapping document for the CoAP schemes
as defined in {{Section 2.4.3 of -svcb}}.
A full SVCB mapping is specified in {{-transport-indication}}.
It generalizes mechanisms for all CoAP services.
This document introduces only the discovery of DoC services.
This document specifies "docpath" as
a single-valued SvcParamKey that is mandatory for DoC SVCB records.
If the "docpath" SvcParamKey is absent, the service should not be considered a valid DoC service.
The docpath is devided up into segments of the absolute path to the DoC resource (docpath-segment),
each a sequence of 1-255 octets.
In ABNF {{-abnf}}:
~~~
docpath-segment = 1*255OCTET
~~~
Note that this restricts the length of each docpath-segment to at most 255 octets.
Paths with longer segments cannot be advertised with the "docpath" SvcParam and are thus NOT
RECOMMENDED for the path to the DoC resource.
The presentation format value of "docpath" SHALL be a comma-separated list ({{Appendix A.1 of -svcb}})
of 0 or more docpath-segments.
The root path "/" is represented by 0 docpath-segments, i.e., an empty list.
The same considerations for the "," and "\" characters in docpath-segments for zone-file
implementations as for the alpn-ids in an "alpn" SvcParam apply ({{Section 7.1.1 of -svcb}}).
The wire-format value for "docpath" consists of 0 or more sequences of octets prefixed by their
respective length as a single octet.
We call this single octet the length octet.
The length octet and the corresponding sequence form a length-value pair.
These length-value pairs are concatenated to form the SvcParamValue.
These pairs MUST exactly fill the SvcParamValue; otherwise, the SvcParamValue is malformed.
Each such length-value pair represents one segment of the absolute path to the DoC resource.
The root path "/" is represented by 0 length-value pairs, i.e., SvcParamValue length 0.
Note that this format uses the same encoding as the "alpn" SvcParam and can reuse the
decoders and encoders for that SvcParam with the adaption that a length of zero is allowed.
As long as each docpath-segment is of length 0 and 24 octets, it is easily transferred into the path
representation in CRIs {{-cri}} by masking each length octet with the CBOR text string major type 3
(`0x60` as an octet, see {{-cbor}}).
Furthermore, it is easily transferable into a sequence of CoAP Uri-Path options by
mapping each length octet into the Option Delta and Option Length of the corresponding CoAP Uri-Path
option, provided the docpath-segments are all of a length between 0 and 12 octets (see {{-coap,
Section 3.1}}).
Likewise, it can be transferred into a URI path-abempty form by replacing each length octet with the "/" character
None of the abovementioned prevent longer docpath-segments than the considered, they just make the
translation harder, as they require to make space for the longer delimiters, in turn requiring to move octets.
To use the service binding from an SVCB RR or DNR Encrypted DNS option, the DoC client MUST send a DoC request constructed from the SvcParams including "docpath".
The construction algorithm for DoC requests is as follows, going through the provided records in order of their priority.
For the purposes of this algorithm, the DoC client is assumed to be SVCB-optional (see {{Section 3 of -svcb}}).
- If the "alpn" SvcParam value for the service is "coap", a CoAP request for CoAP over TLS MUST be constructed {{-coap-tcp}}.
If it is "co", a CoAP request for CoAP over DTLS MUST be constructed {{-coap-dtls-alpn}}.
Any other SvcParamKeys specifying a transport are out of the scope of this document.
- The destination address for the request SHOULD be taken from additional information about the target.
This may include (1) A or AAAA RRs associated with the target name and delivered with the SVCB RR (see {{-ddr}}), (2) "ipv4hint" or "ipv6hint" SvcParams from the SVCB RR (see {{-svcb-dns}}), or (3) from IPv4 or IPv6 addresses provided if DNR {{-dnr}} is used.
As a fallback, an address MAY be queried for the target name of the SVCB record from another DNS service.
- The destination port for the request MUST be taken from the "port" SvcParam value, if present.
Otherwise, take the default port of the CoAP transport, e.g., with regards to this specification TCP port 5684 for "coap" or UDP port 5684 for "co".
This document introduces no limitations on the ports that can be used.
If a malicious SVCB record allows its originator to influence message payloads, {{Section 12 of -svcb}} recommends placing such restrictions in the SVCB mapping document.
The records used in this document only infuence the Uri-Path option.
That option is only sent in the plaintext of an encrytped (D)TLS channel,
and thus does not warrant any limitations.
- The request URI's hostname component MUST be the Authentication Domain Name (ADN) when obtained through DNR
and MUST be the target name of the SVCB record when obtained through a `_dns` query
(if AliasMode is used, to the target name of the AliasMode record).
This can be achieved efficiently by setting that name in TLS Server Name Indication (SNI) {{?RFC8446}},
or by setting the Uri-Host option on each request.
- For each element in the CBOR sequence of the "docpath" SvcParam value, a Uri-Path option MUST be added to the request.
- If the request constructed this way receives a response, the same SVCB record MUST be used for construction of future DoC queries.
If not, or if the endpoint becomes unreachable, the algorithm repeats with the SVCB RR or DNR Encrypted DNS option with the next highest Service Priority as a fallback (see {{Sections 2.4.1 and 3 of -svcb}}).
A more generalized construction algorithm for any CoAP request can be found in {{-transport-indication}}.
### Examples
[^replace-hex]
[^replace-hex]: RFC Ed.: Since the number for "docpath" was not assigned at the time of writing, we
used the hex `ff 0a` (in decimal 65290; from the private use range of SvcParamKeys) throughout
this section. Before publication, please replace `ff 0a` with the hexadecimal representation of
the final value assigned by IANA in this section. Please remove this paragraph after that.
A typical SVCB resource record response for a DoC server at the root path "/" of the server looks
like the following (the "docpath" SvcParam is the last 4 bytes `ff 0a 00 00` in the binary):
Resource record (binary):
04 5f 64 6e 73 07 65 78 61 6d 70 6c 65 03 6f 72
67 00 00 40 00 01 00 00 06 28 00 1e 00 01 03 64
6e 73 07 65 78 61 6d 70 6c 65 03 6f 72 67 00 00
01 00 03 02 63 6f ff 0a 00 00
Resource record (human-readable):
_dns.example.org. 1576 IN SVCB 1 dns.example.org (
alpn=co docpath )
The root path is RECOMMENDED but not required. Here are two examples where the "docpath" represents
paths of varying depth. First, "/dns" is provided in the following example
(the last 8 bytes `ff 0a 00 04 03 64 6e 73`):
Resource record (binary):
04 5f 64 6e 73 07 65 78 61 6d 70 6c 65 03 6f 72
67 00 00 40 00 01 00 00 00 55 00 22 00 01 03 64
6e 73 07 65 78 61 6d 70 6c 65 03 6f 72 67 00 00
01 00 03 02 63 6f ff 0a 00 04 03 64 6e 73
Resource record (human-readable):
_dns.example.org. 85 IN SVCB 1 dns.example.org (
alpn=co docpath=dns )
Second, an examples for the path "/n/s" (the last 8 bytes `ff 0a 00 04 01 6e 01 73`):
Resource record (binary):
04 5f 64 6e 73 07 65 78 61 6d 70 6c 65 03 6f 72
67 00 00 40 00 01 00 00 06 6b 00 22 00 01 03 64
6e 73 07 65 78 61 6d 70 6c 65 03 6f 72 67 00 00
01 00 03 02 63 6f ff 0a 00 04 01 6e 01 73
Resource record (human-readable):
_dns.example.org. 643 IN SVCB 1 dns.example.org (
alpn=co docpath=n,s )
If the server also provides DNS over HTTPS, "dohpath" and "docpath" MAY co-exist:
Resource record (binary):
04 5f 64 6e 73 07 65 78 61 6d 70 6c 65 03 6f 72
67 00 00 40 00 01 00 00 01 ad 00 2b 00 01 03 64
6e 73 07 65 78 61 6d 70 6c 65 03 6f 72 67 00 00
01 00 06 02 68 33 02 63 6f 00 07 00 07 2f 7b 3f
64 6e 73 7d ff 0a 00 00
Resource record (human-readable):
_dns.example.org. 429 IN SVCB 1 dns.example.org (
alpn=h3,co dohpath=/{?dns} docpath )
Basic Message Exchange
======================
The "application/dns-message" Content-Format {#sec:content-format}
--------------------------------------------
This document defines a CoAP Content-Format identifier for the Internet
media type "application/dns-message" to be the mnemonic 553 — based on the port assignment of DNS.
This media type is defined as in {{Section 6 of -doh}}, i.e., a single DNS message encoded in the DNS on-the-wire format {{-dns}}.
Both DoC client and DoC server MUST be able to parse contents in the "application/dns-message" Content-Format.
This document only specifies OPCODE 0 (Query) for DNS over CoAP messages.
Future documents can provide considerations for additional OPCODEs or extend its specification (e.g. by describing whether other CoAP codes need to be used for which OPCODE).
Unless another error takes precedence, a DoC server uses RCODE = 4, NotImp {{-dns}}, in its response to a query with an OPCODE that it does not implement (see also {{sec:resp-examples}}).
DNS Queries in CoAP Requests {#sec:queries}
----------------------------
A DoC client encodes a single DNS query in one or more CoAP request
messages that use the CoAP FETCH {{-coap-fetch}} request method.
Requests SHOULD include an Accept option to indicate the type of content that can be parsed in the response.
Since CoAP provides reliability at the message layer (e.g., through Confirmable messages) the retransmission mechanism of the
DNS protocol as defined in {{-dns}} is not needed.
### Request Format
When sending a CoAP request, a DoC client MUST include the DNS query in the body of the CoAP request.
As specified in {{Section 2.3.1 of -coap-fetch}}, the type of content of the body MUST be indicated using the Content-Format option.
This document specifies the usage of Content-Format "application/dns-message" (for details, see {{sec:content-format}}).
### Support of CoAP Caching {#sec:req-caching}
The DoC client SHOULD set the ID field of the DNS header to 0 to enable a CoAP cache (e.g., a CoAP proxy en-route) to respond to the same DNS queries with a cache entry.
This ensures that the CoAP Cache-Key (see {{-coap-fetch, Section 2}}) does not change when multiple DNS queries for the same DNS data, carried in CoAP requests, are issued.
Apart from losing these caching benefits, there is no harm it not setting it to 0, e.g., when the query was received from somewhere else.
In any instance, a DoC server MUST copy the ID from the query in its response to that query.
### Example {#sec:req-examples}
The following example illustrates the usage of a CoAP message to
resolve "example.org. IN AAAA" based on the URI "coaps://\[2001:db8::1\]/". The
CoAP body is encoded in the "application/dns-message" Content-Format.
FETCH coaps://[2001:db8::1]/
Content-Format: 553 (application/dns-message)
Accept: 553 (application/dns-message)
Payload (binary):
00 00 01 00 00 01 00 00 00 00 00 00 07 65 78 61
6d 70 6c 65 03 6f 72 67 00 00 1c 00 01
Payload (human-readable):
;; ->>Header<<- opcode: QUERY, status: NOERROR, id: 0
;; flags: rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;example.org. IN AAAA
DNS Responses in CoAP Responses
-------------------------------
Each DNS query-response pair is mapped to a CoAP request-response operation.
DNS responses are provided in the body of the CoAP response, i.e., it is also possible to transfer them using block-wise transfer {{-coap-blockwise}}.
A DoC server MUST be able to produce responses in the "application/dns-message"
Content-Format (for details, see {{sec:content-format}}) when requested.
The use of the Accept option in the request is optional.
However, all DoC clients MUST be able to parse a "application/dns-message" response (see also {{sec:content-format}}).
Any response Content-Format other than "application/dns-message" MUST be indicated with
the Content-Format option by the DoC server.
### Response Codes and Handling DNS and CoAP errors {#sec:resp-codes}
A DNS response indicates either success or failure in the RCODE of the DNS header (see {{-dns}}).
It is RECOMMENDED that CoAP responses that carry a parseable DNS response use a 2.05 (Content) response code.
CoAP responses using non-successful response codes MUST NOT contain a DNS response
and MUST only be used for errors in the CoAP layer or when a request does not
fulfill the requirements of the DoC protocol.
Communication errors with an upstream DNS server (e.g., timeouts) MUST be indicated by including a DNS response with the appropriate RCODE in a successful CoAP response, i.e., using a 2.xx response code.
When an error occurs at the CoAP layer, e.g., if an unexpected request method or an unsupported Content-Format in the request are used, the DoC server SHOULD respond with an appropriate CoAP error.
A DoC client might try to repeat a non-successful exchange unless otherwise prohibited.
The DoC client might also decide to repeat a non-successful exchange with a different URI, for instance, when the response indicates an unsupported Content-Format.
### Support of CoAP Caching {#sec:resp-caching}
For reliability and energy saving measures, content decoupling (such as en-route caching on proxies) takes a far greater role than it does in HTTP.
Likewise, CoAP makes it possible to use cache validation to refresh stale cache entries to reduce the number of large response messages.
For cache validation, CoAP implementations regularly use hashing over the message content for ETag generation (see {{-coap, Section 5.10.6}}).
As such, the approach to guarantee the same cache key for DNS responses as proposed in DoH ({{-doh, Section 5.1}}) is not sufficient and needs to be updated so that the TTLs in the response are more often the same regardless of query time.
The DoC server MUST ensure that the sum of the Max-Age value of a CoAP response and any TTL in the
DNS response is less than or equal to the corresponding TTL received from an upstream DNS server.
This also includes the default Max-Age value of 60 seconds (see {{Section 5.10.5 of -coap}}) when no Max-Age option is provided.
The DoC client MUST then add the Max-Age value of the carrying CoAP response to all TTLs in a DNS response on reception and use these calculated TTLs for the associated records.
The RECOMMENDED algorithm for a DoC server to meet the requirement for DoC is as follows:
Set the Max-Age option of a response to the minimum TTL of a DNS response and subtract this value from all TTLs of that DNS response.
This prevents expired records unintentionally being served from an intermediate CoAP cache.
Additionally, if the ETag for cache validation is based on the content of the response, it allows that ETag not to change.
This then remains the case even if the TTL values are updated by an upstream DNS cache.
If only one record set per DNS response is assumed, a simplification of this algorithm is to just set all TTLs in the response to 0 and set the TTLs at the DoC client to the value of the Max-Age option.
If shorter caching periods are plausible, e.g., if the RCODE of the message indicates an error that should only be cached for a minimal duration, the value for the Max-Age option SHOULD be set accordingly.
This value might be 0, but if the DoC server knows that the error will persist, greater values are also conceivable, depending on the projected duration of the error.
The same applies for DNS responses that for any reason do not carry any records with a TTL.
### Examples {#sec:resp-examples}
The following example illustrates the response to the query "example.org. IN
AAAA record", with recursion turned on. Successful responses carry one answer
record including address 2001:db8:1:0:1:2:3:4 and TTL 79689.
A successful response:
2.05 Content
Content-Format: 553 (application/dns-message)
Max-Age: 58719
Payload (human-readable):
;; ->>Header<<- opcode: QUERY, status: NOERROR, id: 0
;; flags: qr rd ad; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;example.org. IN AAAA
;; ANSWER SECTION:
;example.org. 79689 IN AAAA 2001:db8:1:0:1:2:3:4
When a DNS error – NxDomain (RCODE = 3) for "does.not.exist" in this case – is noted in the DNS response, the CoAP response still indicates success.
2.05 Content
Content-Format: 553 (application/dns-message)
Payload (human-readable):
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 0
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;does.not.exist. IN AAAA
As described in {{sec:content-format}}, a DoC server uses NotImp (RCODE = 4) if it does not support an OPCODE—a DNS Update (OPCODE = 5) for "example.org" in this case.
2.05 Content
Content-Format: 553 (application/dns-message)
Payload (human-readable):
;; ->>Header<<- opcode: UPDATE, status: NOTIMP, id: 0
;; flags: qr ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;; QUERY SECTION:
;example.org. IN AAAA
When an error occurs at the CoAP layer, the DoC server responds with
an appropriate CoAP error, for instance 4.15 (Unsupported Content-Format)
if the Content-Format option in the request was not set to
"application/dns-message" and the Content-Format is not otherwise supported by
the server.
4.15 Unsupported Content-Format
[no payload]
Interaction with other CoAP and CoRE Features
=============================================
DNS Push Notifications and CoAP Observe
---------------------------------------
DNS Push Notifications {{-dns-push}} provides the capability to asynchronously notify clients about resource record changes.
However, it results in additional overhead, which conflicts with constrained resources.
This is the reason why it is RECOMMENDED to use CoAP Observe {{-coap-observe}} instead of DNS Push
in the DoC domain.
This is particularly useful if a short-lived record is requested frequently.
The DoC server SHOULD provide Observe capabilities on its DoC resource and do as follows.
If a DoC clients wants to observe a resource record, a DoC server can respond with a notification
and add the client to its list of observers for that resource in accordance to {{-coap-observe}}.
The DoC server MAY subscribe to DNS push notifications for that record.
This involves sending a DNS Subscribe message (see ({{Section 6.2 of -dns-push}}),
instead of a classic DNS query to fetch the
information on behalf of the DoC client.
After the list of observers for a particular DNS query has become empty
(by explicit or implicit cancellation of the observation as per {{Section 3.6 of -coap-observe}}),
and no other reason to subscribe to that request is present,
the DoC server SHOULD cancel the corresponding subscription.
This can involve sending an DNS Unsubscribe message or closing the session (see {{Section 6.4 of -dns-push}}).
As there is no CoAP observer anymore from the perspective of the DoC server, a failure to do so cannot be communicated back to any DoC observer.
As such, error handling (if any) needs to be resolved between the DoC server and the upstream DNS infrastructure.
Whenever the DoC server receives a DNS Push message from the DNS
infrastructure for an observed resource record, the DoC server sends an appropriate Observe notification response
to the DoC client.
A server that responds with notifications (i.e., sends the Observe option) needs to have means of obtaining current resource records.
This may happen through DNS Push, but also by upstream polling or implicit circumstances (e.g., if the DoC server is the authoritative name server for the record and wants to notify about changes).
OSCORE
------
It is RECOMMENDED to carry DNS messages protected using OSCORE {{-oscore}} between the DoC client
and the DoC server. The establishment and maintenance of the OSCORE Security Context is out of the
scope of this document.
{{-cachable-oscore}} describes a method to allow cache retrieval of OSCORE responses and discusses
the corresponding implications on message sizes and security properties.
Mapping DoC to DoH
------------------
This document provides no specification on how to map between DoC and DoH, e.g., at a CoAP-to-HTTP-proxy; such a direct mapping is NOT RECOMMENDED:
rewriting the FETCH method ({{sec:queries}}) and the TTL rewriting ({{sec:resp-caching}}) as
specified in this draft would be non-trivial.
It is RECOMMENDED to use a DNS forwarder to map between DoC and DoH, as would be the case for
mapping between any other pair of DNS transports.
Considerations for Unprotected Use {#sec:unprotected-coap}
==================================
The use of DoC without confidentiality and integrity protection is NOT RECOMMENDED.
Without secure communication, many possible attacks need to be evaluated in the context of
the application's threat model.
This includes known threats for unprotected DNS {{-dns-threats}} {{-dns-privacy}} and CoAP {{Section 11 of -coap}}.
While DoC does not use the random ID of the DNS header (see {{sec:req-caching}}), equivalent protection against off-path poisoning attacks is achieved by using random large token values for unprotected CoAP requests.
If a DoC message is unprotected it MUST use a random token of at least 2 bytes length to mitigate this kind of poisoning attack.
Implementation Status
=====================
{::boilerplate rfc7942}
[^remove-impl-status]
[^remove-impl-status]: RFC Ed.: Please remove this section before publication. When deleting this
section, please also remove RFC7942 from the references of this document.
DoC Client
----------
The authors of this document provide a [DoC client implementation available
in the IoT operating system RIOT][gcoap_dns].
Level of maturity:
: production
Version compatibility:
: draft-ietf-core-dns-over-coap-13
License:
: LGPL-2.1
Contact information:
: `Martine S. Lenders <martine.lend...@tu-dresden.de>`
Last update of this information:
: September 2024
DoC Server
----------
The authors of this document provide a [DoC server implementation in
Python][aiodnsprox].
Level of maturity:
: production
Version compatibility:
: draft-ietf-core-dns-over-coap-13
License:
: MIT
Contact information:
: `Martine S. Lenders <martine.lend...@tu-dresden.de>`
Last update of this information:
: September 2024
Security Considerations
=======================
General CoAP security considerations ({{RFC7252, Section 11}}) apply to DoC.
DoC also inherits the security considerations of the protocols used for secure communication, e.g., OSCORE ({{-oscore, Section 12}}) as well as DTLS 1.2 or newer ({{-dtls12, Section 5}} {{-dtls13, Section 11}}).
Additionally, DoC uses request patterns that require the maintenance of long-lived security
contexts.
{{Section 2.6 of -core-corrclar}} provides insights on what can be done when those are resumed from a new endpoint.
Though DTLS v1.2 {{-dtls12}} was obsoleteted by DTLS v1.3 {{-dtls13}} there are still many CoAP
implementations that still use v1.2 at the time of writing.
As such, this document also accounts for the usage of DTLS v1.2 even though newer versions are
RECOMMENDED when using DTLS to secure CoAP.
When using unprotected CoAP (see {{sec:unprotected-coap}}), setting the ID of a DNS message to 0 as
specified in {{sec:req-caching}} opens the DNS cache of a DoC client to cache poisoning attacks
via response spoofing.
This document requires an unpredictable CoAP token in each DoC query from the client when CoAP is
not secured to mitigate such an attack over DoC (see {{sec:unprotected-coap}}).
For secure communication via (D)TLS or OSCORE, an unpredictable ID against spoofing is not necessary.
Both (D)TLS and OSCORE offer mechanisms to harden against injecting spoofed responses in their protocol design.
Consequently, the ID of the DNS message can be set to 0 without any concern in order to leverage the advantages of CoAP caching.
A DoC client must be aware that the DoC server
may communicate unprotected with the upstream DNS infrastructure, e.g., using DNS over UDP.
DoC can only guarantee confidentiality and integrity of communication between parties for which the
security context is exchanged.
The DoC server may use another security context to communicate upstream with both confidentiality and integrity
(e.g., DNS over QUIC {{-doq}}), but, while recommended, this is opaque to the DoC client on the protocol level.
Record integrity can also be ensured upstream using DNSSEC {{-dnssec}}.
A DoC client may not be able to perform DNSSEC validation,
e.g., due to code size constraints, or due to the size of the responses.
It may trust its DoC server to perform DNSSEC validation;
how that trust is expressed is out of the scope of this document.
For instance, a DoC client may be, configured to use a particular credential by which it recognizes an eligible DoC server.
That information can also imply trust in the DNSSEC validation by that DoC server.
IANA Considerations
===================
[^replace-xxxx]
[^replace-xxxx]: RFC Ed.: throughout this section, please replace
RFC-XXXX with the RFC number of this specification and remove this
note.
This document has the following actions for IANA.
CoAP Content-Formats Registry
-----------------------------
IANA is requested to assign a CoAP Content-Format ID for the "application/dns-message" media
type in the "CoAP Content-Formats" registry, within the "Constrained RESTful Environments (CoRE) Parameters"
registry group {{-coap}}, corresponding to the "application/dns-message" media
type from the "Media Types" registry (see {{-doh}}).
Content Type: application/dns-message
Content Coding: -
ID: 553 (suggested)
Reference: {{-doh}} and \[RFC-XXXX\], {{sec:content-format}}
DNS Service Bindings (SVCB) Registry
------------------------------------
IANA is requested to add the following entry to the "Service Parameter Keys (SvcParamKeys)" registry within the "DNS Service Bindings (SVCB)" registry group.
The definition of this parameter can be found in {{sec:doc-server-selection}}.
| Number | Name | Meaning | Change Controller | Reference |
| ------- | -------------- | ---------------------------------- | ----------------- | --------------- |
| 10 (suggested) | docpath | DNS over CoAP resource path | IETF | \[RFC-XXXX\], {{sec:doc-server-selection}} |
{: #tab-svc-param-keys title="Values for SvcParamKeys"}
Resource Type (rt=) Link Target Attribute Values Registry
---------------------------------------------------------
IANA is requested to add a new Resource Type (rt=) Link Target Attribute "core.dns" to the "Resource Type (rt=) Link Target Attribute Values" registry within the "Constrained RESTful Environments (CoRE) Parameters" registry group.
Value: core.dns
Description: DNS over CoAP resource.
Reference: \[RFC-XXXX\], {{sec:doc-server-selection}}
Operational Considerations
==========================
## Co-existence of different DNS and CoAP transports
Many DNS transports may co-exist on the DoC server, such as DNS over UDP {{-dns}}, DNS over (D)TLS {{-dot}} {{-dodtls}}, DNS over HTTPS {{-doh}}, or DNS over QUIC {{-doq}}.
In principle, transports employing channel or object security should be preferred.
In constrained scenarios, DNS over CoAP is preferable to DNS over DTLS.
The final decision regarding the preference, however, heavily depends on the use case and is therefore left to the implementers or users and is not defined in this document.
CoAP supports Confirmable and Non-Confirmable messages {{-coap}} to deploy different levels of reliability.
This document, however, does not enforce any of these message types, as the decision on which one is appropriate depends on the characteristics of the network where DoC is deployed.
## Redirects
Application-layer redirects (e.g., HTTP) redirct a client to a new server.
In the case of DoC, this leads to a new DNS server.
This new DNS server may provide different answers to the same DNS query than the previous DNS server.
At the time of writing, CoAP does not support redirection.
Future specifications of CoAP redirect may need to consider the impact of different results between previous and new DNS server.
## Proxy Hop-Limit
Mistakes might lead to CoAP proxies forming infinite loops.
Using the CoAP Hop-Limit option {{-coap-hop-limit}} mitigates such loops.
## Error Handling
{{sec:resp-codes}} specifies that DNS operational errors should be reported back to a DoC client
using the appropriate DNS RCODE.
If a DoC client did not receive any successful DNS message from a DoC server for a while, it might
indicate that the DoC server lost connectivity to the upstream DNS infrastructure.
The DoC client should handle this error case like a recursive resolver that lost connectivity to the upstream DNS infrastructure.
In case of CoAP errors, the usual mechanisms for CoAP response codes apply.
## DNS Extensions
DNS extensions that are specific to the choice of transport, such as {{?RFC7828}}, are not applicable to DoC.
--- back
Evaluation {#sec:evaluation}
==========
The authors of this document presented the design, implementation, and analysis of DoC in their
paper "Securing Name Resolution in the IoT: DNS over CoAP" {{DoC-paper}}.
Change Log
==========
[^remove-changelog]
[^remove-changelog]: RFC Ed.: Please remove this section before publication.
Since [draft-ietf-core-dns-over-coap-18]
----------------------------------------
- Address Address Mohamed Boucadair's COMMENT:
- Add Operational Considerations Section
- Make SVCB references normative
- Remove redundant requirement on parsing application/dns-message
- Remove contradicting statement and outdated reference about ALPN
- Add DNS client to Fig. 1
- Clarify recursion termination in the CoAP realm
- Clarify where addresses are coming from with DDR/DNR
- Address Gorry Fairhurst's follow-up DISCUSS:
- Refer to Observe terminology in Section 2
- Clarify registration
- Provide alternative observation examples
- Clarify that error handling is in the hands of the DoC server
Since [draft-ietf-core-dns-over-coap-17]
----------------------------------------
- Address Roman Danyliw's COMMENT:
- Remove unused RFC8742 reference
- Address Vladimír Čunát's DNSDIR review
- Address Éric Vyncke' COMMENT:
- Mention OPCODE 0 in Abstract and Introduction
- Reference to STD13 instead of RFC1035
- Provide extension pointers for future documents on other OPCODES
- Use only singular for example section if there is only one example
- Improvements on DNSSEC
- Hyphenate link-layer as modifier to frame
- Address Paul Wouters's DISCUSS and COMMENT:
- Remove unnecessary and confusing ad flag from query example
- Phrase full SVCB mapping sentence more neutrally
- Address Gorry Fairhurst's COMMENT:
- Add note (in addition to the `RFC Ed.:`) about paragraph removal
- Add references for "coap" and "co" ALPN to SvcParam algorithm
- Address Gorry's nits
- Address Gorry Fairhurst's DISCUSS:
- Update push notifications
- observation: Do not use normative language
- Address Orie Steele's COMMENT:
- Automatic configuration MUST only be done from a trusted source
- Remove confusing and unnecessary MAY
- Remove normative repeat of SvcParam algorithm by citing RFC 9461
- Fix wording around Accept option
- Address Deb Cooley's COMMENT:
- Group (D)TLS references
- Automatic configuration MUST only be done from a trusted source
- Fix wording about unpredictable ID and spoofing
- Remove confusing "e.g."
Since [draft-ietf-core-dns-over-coap-16]
----------------------------------------
- Mention TLS as possible protection mechanism in abstract and intro
- Fix representation format in the docpath examples
- Make docpath wire-format paragraph easier to parse
Since [draft-ietf-core-dns-over-coap-15]
----------------------------------------
- Address Genart and Artart review:
- Add editor's note about removing RFC7228 reference in case rfc7228bis comes out before
publication
- Address minor nits
- Resolve less well-known abbreviations
- Name default ports for "coap" and "co"
- Add reasoning why we also consider DTLS v1.2 (RFC 6347)
- Add illustrative reference for ETag generation
- Address DNS SVCB SvcParamKeys IANA expert review:
- docpath: clarifications and examples
- Rework representation format and wire-format of "docpath"
- State that we don't do the full SVCB mapping
- Explicitly do not limit what port= can do.
- port limitations: We're not the SVCB mapping document
- Address Tsvart Review
- Prefer ADN for Uri-Host; don't prescribe *how* it is set
Since [draft-ietf-core-dns-over-coap-14]
----------------------------------------
- Remove superfluous and confusing step in SVCB to request algorithm
- Address AD review:
- Remove RFC8949 as CBOR diagnostic notation reference
- CoRE-specific FETCH method -> CoAP-specific FETCH method
- Remove double reference to BCP 219
- Fix wording and references around SVCB records and ALPN
- Move format description for examples to Terminology section
- Retitle section 5 to "Interaction with other CoAP and CoRE Features"
- Make prevention of poisoning attacks normative for unprotected CoAP
- Provide specs on if the SHOULD on ID=0 does not apply
- Make construction algorithm normative
- Add definition for CoRE
- General grammar, wording, and spelling cleanups
Since [draft-ietf-core-dns-over-coap-13]
----------------------------------------
- Address shepherd review
Since [draft-ietf-core-dns-over-coap-12]
----------------------------------------
- Address Esko's review
- Address Marcos's review
- Address Mikolai's review
Since [draft-ietf-core-dns-over-coap-10]
----------------------------------------
- Replace imprecise or wrong terms:
- disjunct => distinct
- unencrypted CoAP => unprotected CoAP
- security mode => confidential communication
- Pull in definition of CBOR sequences and their EDN
- Fix broken external section references
- Define terminology for "upstream DNS infrastructure" and "upstream DNS server"
- Fix wording on DNS error handling
- Clarify that any OpCode beyond 0 is not supported for now and remove now redundant DNS Upgrade
section as a consequence
- Clarify that the DoC/DoH mapping is what is NOT RECOMMENDED
- Avoid use of undefined term “CoAP resource identifier”
- Discuss Max-Age option value in an error case
- Add human-readable format to examples
- General language check pass
Since [draft-ietf-core-dns-over-coap-09]
----------------------------------------
- Update SVCB SvcParamKey
- Update corr-clar reference
- Add reference to DNS Update [\[RFC2136\]](https://datatracker.ietf.org/doc/html/rfc2136), clarify that it is currently not considered
- Add to security considerations: unprotected upstream DNS and DNSSEC
Since [draft-ietf-core-dns-over-coap-08]
----------------------------------------
- Update Cenk's Affiliation
Since [draft-ietf-core-dns-over-coap-07]
----------------------------------------
- Address IANA early review #1368678
- Update normative reference to CoAP over DTLS alpn SvcParam
- Add missing DTLSv1.2 reference
- Security considerations: Point into corr-clar-future
- Implementation Status: Update to current version
Since [draft-ietf-core-dns-over-coap-06]
----------------------------------------
- Add "docpath" SVCB ParamKey definition
- IANA fixes
+ Use new column names (see Errata 4954)
+ Add reference to RFC 8484 for application/dns-message Media Type
+ IANA: unify self references
Since [draft-ietf-core-dns-over-coap-05]
----------------------------------------
- Add references to relevant SVCB/DNR RFCs and drafts
Since [draft-ietf-core-dns-over-coap-04]
----------------------------------------
- Add note on cacheable OSCORE
- Address early IANA review
Since [draft-ietf-core-dns-over-coap-03]
----------------------------------------
- Amended Introduction with short contextualization of constrained environments
- Add {{sec:evaluation}} on evaluation
Since [draft-ietf-core-dns-over-coap-02]
----------------------------------------
- Move implementation details to Implementation Status (in accordance with {{RFC7942}})
- Recommend root path to keep the CoAP options small
- Set Content-Format for application/dns-message to 553
- SVCB/DNR: Move to Server Selection Section but leave TBD based on DNSOP discussion for now
- Clarify that DoC and DoH are distinct
- Clarify mapping between DoC and DoH
- Update considerations on unprotected use
- Don't call OSCORE end-to-end encrypted
Since [draft-ietf-core-dns-over-coap-01]
----------------------------------------
- Specify DoC server role in terms of DNS terminology
- Clarify communication of DoC to DNS infrastructure is agnostic of the transport
- Add subsection on how to implement DNS Push in DoC
- Add appendix on reference implementation
Since [draft-ietf-core-dns-over-coap-00]
----------------------------------------
- SVGify ASCII art
- Move section on "DoC Server Considerations" (was Section 5.1) to its own draft
([draft-lenders-dns-cns])
- Replace layer violating statement for CON with statement of fact
- Add security considerations on ID=0
Since [draft-lenders-dns-over-coap-04]
--------------------------------------
- Removed change log of draft-lenders-dns-over-coap
# Acknowledgments
{:unnumbered}
The authors of this document want to thank Mike Bishop, Carsten Bormann, Mohamed Boucadair, Deb Cooley, Vladimír Čunát, Roman Danyliw, Elwyn B. Davies, Esko Dijk, Gorry Fairhurst, Thomas Fossati, Mikolai Gütschow, Todd Herr, Tommy Pauly, Jan Romann, Ben Schwartz, Orie Steele, Marco Tiloca, Éric Vyncke, Tim Wicinski, and Paul Wouters for their feedback and comments.
[draft-ietf-core-dns-over-coap-18]: https://datatracker.ietf.org/doc/html/draft-ietf-core-dns-over-coap-18
[draft-ietf-core-dns-over-coap-17]: https://datatracker.ietf.org/doc/html/draft-ietf-core-dns-over-coap-17
[draft-ietf-core-dns-over-coap-16]: https://datatracker.ietf.org/doc/html/draft-ietf-core-dns-over-coap-16
[draft-ietf-core-dns-over-coap-15]: https://datatracker.ietf.org/doc/html/draft-ietf-core-dns-over-coap-15
[draft-ietf-core-dns-over-coap-14]: https://datatracker.ietf.org/doc/html/draft-ietf-core-dns-over-coap-14
[draft-ietf-core-dns-over-coap-13]: https://datatracker.ietf.org/doc/html/draft-ietf-core-dns-over-coap-13
[draft-ietf-core-dns-over-coap-12]: https://datatracker.ietf.org/doc/html/draft-ietf-core-dns-over-coap-12
[draft-ietf-core-dns-over-coap-10]: https://datatracker.ietf.org/doc/html/draft-ietf-core-dns-over-coap-10
[draft-ietf-core-dns-over-coap-09]: https://datatracker.ietf.org/doc/html/draft-ietf-core-dns-over-coap-09
[draft-ietf-core-dns-over-coap-08]: https://datatracker.ietf.org/doc/html/draft-ietf-core-dns-over-coap-08
[draft-ietf-core-dns-over-coap-07]: https://datatracker.ietf.org/doc/html/draft-ietf-core-dns-over-coap-07
[draft-ietf-core-dns-over-coap-06]: https://datatracker.ietf.org/doc/html/draft-ietf-core-dns-over-coap-06
[draft-ietf-core-dns-over-coap-05]: https://datatracker.ietf.org/doc/html/draft-ietf-core-dns-over-coap-05
[draft-ietf-core-dns-over-coap-04]: https://datatracker.ietf.org/doc/html/draft-ietf-core-dns-over-coap-04
[draft-ietf-core-dns-over-coap-03]: https://datatracker.ietf.org/doc/html/draft-ietf-core-dns-over-coap-03
[draft-ietf-core-dns-over-coap-02]: https://datatracker.ietf.org/doc/html/draft-ietf-core-dns-over-coap-02
[draft-ietf-core-dns-over-coap-01]: https://datatracker.ietf.org/doc/html/draft-ietf-core-dns-over-coap-01
[draft-ietf-core-dns-over-coap-00]: https://datatracker.ietf.org/doc/html/draft-ietf-core-dns-over-coap-00
[draft-lenders-dns-cns]: https://datatracker.ietf.org/doc/draft-lenders-dns-cns/
[draft-lenders-dns-over-coap-04]: https://datatracker.ietf.org/doc/html/draft-lenders-dns-over-coap-04
[gcoap_dns]: https://doc.riot-os.org/group__net__gcoap__dns.html
[aiodnsprox]: https://github.com/anr-bmbf-pivot/aiodnsprox
smime.p7s
Description: S/MIME Cryptographic Signature
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