| Internet-Draft | EDE NTA | July 2026 |
| Farrokhi, et al. | Expires 20 January 2027 | [Page] |
This document describes a mechanism for disclosing that a Negative Trust Anchor (NTA) was in effect at the time that a DNS response was generated, using an Extended DNS Error (EDE).¶
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/.¶
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."¶
This Internet-Draft will expire on 20 January 2027.¶
Copyright (c) 2026 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 Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.¶
[RFC8914] defines the Extended DNS Error (EDE) mechanism, which allows DNS servers to encode additional information in a DNS response.¶
[RFC7646] defines the concept of a DNSSEC Negative Trust Anchor (NTA), an operational mechanism by which a validating resolver can be configured to temporarily disable DNSSEC validation for a specific domain to mitigate misconfiguration.¶
A resolver with an NTA in effect might send a response that ordinarily would have been suppressed because of validation failures. This document defines a new EDE that can be sent within a response to indicate that the response was subject to an active NTA.¶
A further goal of this signal is transparency toward end users and applications. Section 3.1 of [RFC7646] recommends that operators disclose the NTAs they have in place, for example on a website, and notes that no in-band DNS signal exists to indicate that an NTA is in effect. This document defines that in-band signal, complementing such out-of-band disclosure.¶
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.¶
This document assumes a familiarity with common DNS terminology as described in [RFC9499].¶
A response that includes one or more instances of EDE 33 was generated with a covering NTA [RFC7646] in effect.¶
As with all EDEs, the EDE defined in this document is diagnostic; per Section 6 of [RFC8914] a client MUST NOT use its presence to alter protocol processing. The inclusion of this EDE in a response does not change AD bit processing in DNS messages in any way. The only purpose of this EDE is to provide additional information about the response in which it appears.¶
This EDE is intended for use in DNS responses sent by a DNS resolver with a configured NTA and MUST NOT be included in other responses. For example, a DNS response sent by an authoritative-only DNS server, which does not perform validation and hence has no obvious use for an NTA, SHOULD NOT include this EDE.¶
An operator that applies an NTA SHOULD return this EDE in affected responses, so that end users and applications can tell that the response may not have been DNSSEC-validated. This complements, and does not replace, the disclosure recommended in Section 3.1 of [RFC7646].¶
A response might be affected by an NTA for various reasons, not just in the case where the QNAME is subordinate to the domain for which an NTA has been configured. In any case, a resolver MAY include this EDE on any responses while an NTA is in effect, regardless of whether the presence of the NTA had a material effect on the contents of the response.¶
A resolver with multiple NTAs in place simultaneously MAY include multiple instances of this EDE in a single response. Multiple instances of this EDE in a single response might each have different EXTRA-TEXT fields, for example, and might each describe a different active, applicable NTA. When multiple instances of this EDE are included in a response, the EXTRA-TEXT field in each instance MUST be populated.¶
The operator MAY use the EXTRA-TEXT field to add context about the NTA, such as the name at which it was configured, the reason it was put in place, a reference where more information can be found, or its expected duration. As noted in Section 2 of [RFC8914], EXTRA-TEXT is intended for human consumption; operators SHOULD keep it readable and SHOULD NOT include private or sensitive information.¶
Structured data MAY be included in the EXTRA-TEXT field, as described in [I-D.ietf-dnsop-structured-dns-error]. The JSON Names "d" and "t" have been registered for this purpose (see Section 5) and should be used and interpreted when used with this EDE as follows:¶
| JSON Name | Use and interpretation for this EDE |
|---|---|
| d | The domain name at which an active NTA has been configured |
| t | An indicative time at which this NTA might be expected to remain in place until |
Note that it is usual for NTAs to be configured in response to unplanned events that have afflicted unaffiliated third parties, and hence consumers of structured EXTRA-TEXT should be interpret timestamps with generous flexibility.¶
The IANA has made the following allocation in the "Extended DNS Error Codes" registry under the "Domain Name System (DNS) Parameters" registry group:¶
| INFO-CODE | Purpose | Reference |
|---|---|---|
| 33 | Negative Trust Anchor | This document |
The IANA is directed to update the "EXTRA-TEXT JSON Names" registry under the "Domain Name System (DNS) Parameters) registry group by adding the following entries:¶
| JSON Name | Field Meaning | Description | Reference |
|---|---|---|---|
| d | domain-name | A fully-qualified domain name (in the case of an IDN, containing only A-labels) with no trailing period | This document |
| t | timestamp | A timestamp in [RFC3339] format | This document |
An NTA represents an intentional, operator-driven suspension of DNSSEC validation for a specific domain. See [RFC7646] for further discussion of the operational and security implications of NTAs.¶
The presence of the EDE defined in this document does not modify AD bit processing in DNS messages, and its only purpose is to provide additional information.¶
EDEs encoded in DNS messages carry no cryptographic signatures and hence enjoy no inherent integrity protection. An on-path attacker could add, remove, or modify an EDE. Clients that require integrity protection of these signals should use a suitable mechanism, such as TSIG [RFC8945], SIG(0) [RFC2931] or an authenticated and encrypted transport protocol such as DNS over TLS [RFC7858] or DNS over HTTPS [RFC8484]. See Section 6 of [RFC8914] for more discussion.¶
The authors acknowledge review and ideas from Carlos Horowicz, Mukund Sivaraman, Ralf Weber, Warren Kumari, Robert Edmonds and Petr Spacek.¶
The following examples use configurations that exist in the DNS at the time of writing. Readers from the future may need to create analogous configurations in order to reproduce the results illustrated here.¶
These examples were constructed using the well-known diagnostic tool dig, as shipped with BIND9. The output was hand-edited slightly to fit the formatting constraints of the document, but is otherwise consistent with the original output.¶
The zone NTAMUCH.ORG is signed and an intact and functional path of trust exists back to the root zone. An NTA is applied to the domain NTAMUCH.ORG at the security-aware, validating resolver 1.1.1.1, but not at 9.9.9.9.¶
jabley@manta ~ % dig @1.1.1.1 NTAMUCH.ORG SOA +nocd +rec +multiline
; <<>> DiG 9.20.24 <<>> @1.1.1.1 NTAMUCH.ORG SOA +nocd +rec +multiline
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 46491
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
; EDE: 33: (a Negative Trust Anchor has been applied for this query
; (see RFC 7646))
;; QUESTION SECTION:
;NTAMUCH.ORG. IN SOA
;; ANSWER SECTION:
NTAMUCH.ORG. 1800 IN SOA barbara.ns.cloudflare.com. dns.cloudflare.com. (
2407706086 ; serial
10000 ; refresh (2 hours 46 minutes 40 seconds)
2400 ; retry (40 minutes)
604800 ; expire (1 week)
1800 ; minimum (30 minutes)
)
;; Query time: 21 msec
;; SERVER: 1.1.1.1#53(1.1.1.1) (UDP)
;; WHEN: Fri Jun 26 10:49:10 CEST 2026
;; MSG SIZE rcvd: 181
jabley@manta ~ % dig @9.9.9.9 NTAMUCH.ORG SOA +nocd +rec +multiline
; <<>> DiG 9.20.24 <<>> @9.9.9.9 NTAMUCH.ORG SOA +nocd +rec +multiline
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 7960
;; flags: qr rd ra ad; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;NTAMUCH.ORG. IN SOA
;; ANSWER SECTION:
NTAMUCH.ORG. 1767 IN SOA barbara.ns.cloudflare.com. dns.cloudflare.com. (
2407706086 ; serial
10000 ; refresh (2 hours 46 minutes 40 seconds)
2400 ; retry (40 minutes)
604800 ; expire (1 week)
1800 ; minimum (30 minutes)
)
;; Query time: 11 msec
;; SERVER: 9.9.9.9#53(9.9.9.9) (UDP)
;; WHEN: Fri Jun 26 10:49:20 CEST 2026
;; MSG SIZE rcvd: 105
jabley@manta ~ %
¶
The zone BROKEN.NTAMUCH.ORG is delegated from the NTAMUCH.ORG zone using an accurate NS RRSet both sides of the zone cut, but a deliberately-fabricated DS RRSet at on the parent side. Records in the child zone are not signed, and no child zone DNSKEY RRSet exists. The effect is a secure delegation to an unsigned zone, a broken configuration that we should expect to trigger validation failures.¶
The same NTA as described in the previous example is in place for the domain NTAMUCH.ORG on the resolver 1.1.1.1, but, again, not on the resolver 9.9.9.9.¶
Both resolvers include different EDEs in the response which illustrate the problem, but note the different RCODEs: with the NTA in place, the 1.1.1.1 resolver returns an answer with NOERROR while the 9.9.9.9 resolver with no applicable NTA correctly returns RCODE SERVFAIL.¶
jabley@manta ~ % dig @1.1.1.1 BROKEN.NTAMUCH.ORG SOA +nocd +rec +multiline
; <<>> DiG 9.20.24 <<>> @1.1.1.1 BROKEN.NTAMUCH.ORG SOA +nocd +rec +multiline
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 25660
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
; EDE: 9 (DNSKEY Missing): (no SEP matching the DS found for
; broken.ntamuch.org.)
; EDE: 33: (a Negative Trust Anchor has been applied for this
; query (see RFC 7646))
;; QUESTION SECTION:
;BROKEN.NTAMUCH.ORG. IN SOA
;; ANSWER SECTION:
BROKEN.NTAMUCH.ORG. 300 IN SOA maleah.ns.cloudflare.com. dns.cloudflare.com. (
2407705944 ; serial
10000 ; refresh (2 hours 46 minutes 40 seconds)
2400 ; retry (40 minutes)
604800 ; expire (1 week)
1800 ; minimum (30 minutes)
)
;; Query time: 20 msec
;; SERVER: 1.1.1.1#53(1.1.1.1) (UDP)
;; WHEN: Fri Jun 26 10:52:52 CEST 2026
;; MSG SIZE rcvd: 245
jabley@manta ~ % dig @9.9.9.9 BROKEN.NTAMUCH.ORG SOA +nocd +rec +multiline
; <<>> DiG 9.20.24 <<>> @9.9.9.9 BROKEN.NTAMUCH.ORG SOA +nocd +rec +multiline
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 20047
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
; EDE: 9 (DNSKEY Missing)
;; QUESTION SECTION:
;BROKEN.NTAMUCH.ORG. IN SOA
;; Query time: 116 msec
;; SERVER: 9.9.9.9#53(9.9.9.9) (UDP)
;; WHEN: Fri Jun 26 10:53:05 CEST 2026
;; MSG SIZE rcvd: 53
jabley@manta ~ %
¶