< draft-ietf-dnsop-extended-error-12.txt   draft-ietf-dnsop-extended-error-13.txt >
Network Working Group W. Kumari Network Working Group W. Kumari
Internet-Draft Google Internet-Draft Google
Intended status: Standards Track E. Hunt Intended status: Standards Track E. Hunt
Expires: April 3, 2020 ISC Expires: June 20, 2020 ISC
R. Arends R. Arends
ICANN ICANN
W. Hardaker W. Hardaker
USC/ISI USC/ISI
D. Lawrence D. Lawrence
Oracle + Dyn Oracle + Dyn
October 01, 2019 December 18, 2019
Extended DNS Errors Extended DNS Errors
draft-ietf-dnsop-extended-error-12 draft-ietf-dnsop-extended-error-13
Abstract Abstract
This document defines an extensible method to return additional This document defines an extensible method to return additional
information about the cause of DNS errors. Though created primarily information about the cause of DNS errors. Though created primarily
to extend SERVFAIL to provide additional information about the cause to extend SERVFAIL to provide additional information about the cause
of DNS and DNSSEC failures, the Extended DNS Errors option defined in of DNS and DNSSEC failures, the Extended DNS Errors option defined in
this document allows all response types to contain extended error this document allows all response types to contain extended error
information. Extended DNS Error information does not change the information. Extended DNS Error information does not change the
processing of RCODEs. processing of RCODEs.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 3, 2020. This Internet-Draft will expire on June 20, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction and background . . . . . . . . . . . . . . . . . 3 1. Introduction and background . . . . . . . . . . . . . . . . . 3
1.1. Requirements notation . . . . . . . . . . . . . . . . . . 4 1.1. Requirements notation . . . . . . . . . . . . . . . . . . 4
2. Extended DNS Error EDNS0 option format . . . . . . . . . . . 4 2. Extended DNS Error EDNS0 option format . . . . . . . . . . . 4
3. Defined Extended DNS Errors . . . . . . . . . . . . . . . . . 5 3. Extended DNS Error Processing . . . . . . . . . . . . . . . . 5
3.1. Extended DNS Error Code 0 - Other . . . . . . . . . . . . 5 4. Defined Extended DNS Errors . . . . . . . . . . . . . . . . . 5
3.2. Extended DNS Error Code 1 - 4.1. Extended DNS Error Code 0 - Other . . . . . . . . . . . . 5
Unsupported DNSKEY Algorithm . . . . . . . . . . . . . . 5 4.2. Extended DNS Error Code 1 -
3.3. Extended DNS Error Code 2 - Unsupported DS Unsupported DNSKEY Algorithm . . . . . . . . . . . . . . 6
Digest Type . . . . . . . . . . . . . . . . . . . . . . . 5 4.3. Extended DNS Error Code 2 - Unsupported DS
3.4. Extended DNS Error Code 3 - Stale Answer . . . . . . . . 5 Digest Type . . . . . . . . . . . . . . . . . . . . . . . 6
3.5. Extended DNS Error Code 4 - Forged Answer . . . . . . . . 6 4.4. Extended DNS Error Code 3 - Stale Answer . . . . . . . . 6
3.6. Extended DNS Error Code 5 - DNSSEC Indeterminate . . . . 6 4.5. Extended DNS Error Code 4 - Forged Answer . . . . . . . . 6
3.7. Extended DNS Error Code 6 - DNSSEC Bogus . . . . . . . . 6 4.6. Extended DNS Error Code 5 - DNSSEC Indeterminate . . . . 6
3.8. Extended DNS Error Code 7 - Signature Expired . . . . . . 6 4.7. Extended DNS Error Code 6 - DNSSEC Bogus . . . . . . . . 6
3.9. Extended DNS Error Code 8 - Signature Not Yet Valid . . . 6 4.8. Extended DNS Error Code 7 - Signature Expired . . . . . . 6
3.10. Extended DNS Error Code 9 - DNSKEY Missing . . . . . . . 6 4.9. Extended DNS Error Code 8 - Signature Not Yet Valid . . . 6
3.11. Extended DNS Error Code 10 - RRSIGs Missing . . . . . . . 6 4.10. Extended DNS Error Code 9 - DNSKEY Missing . . . . . . . 7
3.12. Extended DNS Error Code 11 - No Zone Key Bit Set . . . . 6 4.11. Extended DNS Error Code 10 - RRSIGs Missing . . . . . . . 7
3.13. Extended DNS Error Code 12 - NSEC Missing . . . . . . . . 6 4.12. Extended DNS Error Code 11 - No Zone Key Bit Set . . . . 7
3.14. Extended DNS Error Code 13 - Cached Error . . . . . . . . 7 4.13. Extended DNS Error Code 12 - NSEC Missing . . . . . . . . 7
3.15. Extended DNS Error Code 14 - Not Ready . . . . . . . . . 7 4.14. Extended DNS Error Code 13 - Cached Error . . . . . . . . 7
3.16. Extended DNS Error Code 15 - Blocked . . . . . . . . . . 7 4.15. Extended DNS Error Code 14 - Not Ready . . . . . . . . . 7
3.17. Extended DNS Error Code 16 - Censored . . . . . . . . . . 7 4.16. Extended DNS Error Code 15 - Blocked . . . . . . . . . . 7
3.18. Extended DNS Error Code 17 - Filtered . . . . . . . . . . 7 4.17. Extended DNS Error Code 16 - Censored . . . . . . . . . . 7
3.19. Extended DNS Error Code 18 - Prohibited . . . . . . . . . 7 4.18. Extended DNS Error Code 17 - Filtered . . . . . . . . . . 7
3.20. Extended DNS Error Code 19 - Stale NXDOMAIN Answer . . . 7 4.19. Extended DNS Error Code 18 - Prohibited . . . . . . . . . 8
3.21. Extended DNS Error Code 20 - Not Authoritative . . . . . 8 4.20. Extended DNS Error Code 19 - Stale NXDOMAIN Answer . . . 8
3.22. Extended DNS Error Code 21 - Not Supported . . . . . . . 8 4.21. Extended DNS Error Code 20 - Not Authoritative . . . . . 8
3.23. Extended DNS Error Code 22 - No Reachable Authority . . . 8 4.22. Extended DNS Error Code 21 - Not Supported . . . . . . . 8
3.24. Extended DNS Error Code 23 - Network Error . . . . . . . 8 4.23. Extended DNS Error Code 22 - No Reachable Authority . . . 8
3.25. Extended DNS Error Code 24 - Invalid Data . . . . . . . . 8 4.24. Extended DNS Error Code 23 - Network Error . . . . . . . 8
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 4.25. Extended DNS Error Code 24 - Invalid Data . . . . . . . . 8
4.1. A New Extended DNS Error Code EDNS Option . . . . . . . . 8 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
4.2. New Registry Table for Extended DNS Error Codes . . . . . 8 5.1. A New Extended DNS Error Code EDNS Option . . . . . . . . 9
5. Security Considerations . . . . . . . . . . . . . . . . . . . 11 5.2. New Registry Table for Extended DNS Error Codes . . . . . 9
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11 6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12
7.1. Normative References . . . . . . . . . . . . . . . . . . 12 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.2. Informative References . . . . . . . . . . . . . . . . . 12 8.1. Normative References . . . . . . . . . . . . . . . . . . 12
8.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction and background 1. Introduction and background
There are many reasons that a DNS query may fail, some of them There are many reasons that a DNS query may fail, some of them
transient, some permanent; some can be resolved by querying another transient, some permanent; some can be resolved by querying another
server, some are likely best handled by stopping resolution. server, some are likely best handled by stopping resolution.
Unfortunately, the error signals that a DNS server can return are Unfortunately, the error signals that a DNS server can return are
very limited, and are not very expressive. This means that very limited, and are not very expressive. This means that
applications and resolvers often have to "guess" at what the issue is applications and resolvers often have to "guess" at what the issue is
skipping to change at page 4, line 20 skipping to change at page 4, line 21
in a DNS message. in a DNS message.
1.1. Requirements notation 1.1. Requirements notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Extended DNS Error EDNS0 option format 2. Extended DNS Error EDNS0 option format
This draft uses an EDNS0 ([RFC2671]) option to include Extended DNS This draft uses an EDNS0 ([RFC6891]) option to include Extended DNS
Error (EDE) information in DNS messages. The option is structured as Error (EDE) information in DNS messages. The option is structured as
follows: follows:
1 1 1 1 1 1 1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
0: | OPTION-CODE | 0: | OPTION-CODE |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
2: | OPTION-LENGTH | 2: | OPTION-LENGTH |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
skipping to change at page 4, line 43 skipping to change at page 4, line 44
6: / EXTRA-TEXT ... / 6: / EXTRA-TEXT ... /
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
Field definition details: Field definition details:
o OPTION-CODE, 2-octets/16-bits (defined in [RFC6891]]), for EDE is o OPTION-CODE, 2-octets/16-bits (defined in [RFC6891]]), for EDE is
TBD. [RFC Editor: change TBD to the proper code once assigned by TBD. [RFC Editor: change TBD to the proper code once assigned by
IANA.] IANA.]
o OPTION-LENGTH, 2-octets/16-bits ((defined in [RFC6891]]) contains o OPTION-LENGTH, 2-octets/16-bits ((defined in [RFC6891]]) contains
the length of the payload (everything after OPTION-LENGTH) in the length of the payload (everything after OPTION-LENGTH) in
octets and should be 4 plus the length of the EXTRA-TEXT section octets and should be 2 plus the length of the EXTRA-TEXT field
(which may be a zero-length string). (which may be a zero-length string).
o INFO-CODE, 16-bits, which is the principal contribution of this o INFO-CODE, 16-bits, which is the principal contribution of this
document. This 16-bit value, encoded in network (MSB) byte order, document. This 16-bit value, encoded in network (MSB) byte order,
provides the additional context for the RESPONSE-CODE of the DNS provides the additional context for the RESPONSE-CODE of the DNS
message. The INFO-CODE serves as an index into the "Extended DNS message. The INFO-CODE serves as an index into the "Extended DNS
Errors" registry Section 4.1. Errors" registry Section 5.1.
o EXTRA-TEXT, a variable length, UTF-8 encoded, text field that may o EXTRA-TEXT, a variable length, UTF-8 encoded, text field that may
hold additional textual information. Note: EXTRA-TEXT may be zero hold additional textual information. Note: EXTRA-TEXT may be zero
octets in length, indicating there is no EXTRA-TEXT included. octets in length, indicating there is no EXTRA-TEXT included.
Care should be taken not to leak private information that an Care should be taken not to leak private information that an
observer would not otherwise have access to, such as account observer would not otherwise have access to, such as account
numbers. numbers.
The Extended DNS Error (EDE) option can be included in any response The Extended DNS Error (EDE) option can be included in any response
(SERVFAIL, NXDOMAIN, REFUSED, and even NOERROR, etc) to a query that (SERVFAIL, NXDOMAIN, REFUSED, and even NOERROR, etc) to a query that
includes OPT Pseudo-RR [RFC6891]. This document includes a set of includes OPT Pseudo-RR [RFC6891]. This document includes a set of
initial codepoints (and requests to the IANA to add them to the initial codepoints (and requests to the IANA to add them to the
registry), but is extensible via the IANA registry to allow registry), but is extensible via the IANA registry to allow
additional error and information codes to be defined in the future. additional error and information codes to be defined in the future.
3. Defined Extended DNS Errors 3. Extended DNS Error Processing
When the response grows beyond the requestor's UDP payload size
[RFC6891], servers SHOULD truncate messages by dropping EDE options
before dropping other data from packets. Implementations SHOULD set
the truncation bit when dropping EDE options.
When a resolver or forwarder receives an EDE option, whether or not
(and how) to pass along EDE information on to their original client
is implementation dependent. Implementations MAY choose to not
forward information, or they MAY choose to create a new EDE option(s)
that conveys the information encoded in the received EDE. When doing
so, care should be taken to ensure any information is properly
attributed since an EDNS0 option received by the original client will
be perceived only to have come from the resolver or forwarder sending
it.
4. Defined Extended DNS Errors
This document defines some initial EDE codes. The mechanism is This document defines some initial EDE codes. The mechanism is
intended to be extensible, and additional code-points can be intended to be extensible, and additional code-points can be
registered in the "Extended DNS Errors" registry Section 4.1. The registered in the "Extended DNS Errors" registry Section 5.1. The
INFO-CODE from the EDE EDNS option is used to serve as an index into INFO-CODE from the EDE EDNS option is used to serve as an index into
the "Extended DNS Error" IANA registry, the initial values for which the "Extended DNS Error" IANA registry, the initial values for which
are defined in the following sub-sections. are defined in the following sub-sections.
3.1. Extended DNS Error Code 0 - Other 4.1. Extended DNS Error Code 0 - Other
The error in question falls into a category that does not match known The error in question falls into a category that does not match known
extended error codes. Implementations SHOULD include a EXTRA-TEXT extended error codes. Implementations SHOULD include a EXTRA-TEXT
value to augment this error code with additional information. value to augment this error code with additional information.
3.2. Extended DNS Error Code 1 - Unsupported DNSKEY Algorithm 4.2. Extended DNS Error Code 1 - Unsupported DNSKEY Algorithm
The resolver attempted to perform DNSSEC validation, but a DNSKEY The resolver attempted to perform DNSSEC validation, but a DNSKEY
RRSET contained only unsupported DNSSEC algorithms. RRSET contained only unsupported DNSSEC algorithms.
3.3. Extended DNS Error Code 2 - Unsupported DS Digest Type 4.3. Extended DNS Error Code 2 - Unsupported DS Digest Type
The resolver attempted to perform DNSSEC validation, but a DS RRSET The resolver attempted to perform DNSSEC validation, but a DS RRSET
contained only unsupported Digest Types. contained only unsupported Digest Types.
3.4. Extended DNS Error Code 3 - Stale Answer 4.4. Extended DNS Error Code 3 - Stale Answer
The resolver was unable to resolve answer within its time limits and The resolver was unable to resolve answer within its time limits and
decided to answer with previously cached data instead of answering decided to answer with previously cached data instead of answering
with an error. This is typically caused by problems communicating with an error. This is typically caused by problems communicating
with an authoritative serever, possibly as result of a DoS attack with an authoritative serever, possibly as result of a DoS attack
against another network. against another network.
3.5. Extended DNS Error Code 4 - Forged Answer 4.5. Extended DNS Error Code 4 - Forged Answer
For policy reasons (legal obligation, or malware filtering, for For policy reasons (legal obligation, or malware filtering, for
instance), an answer was forged. Note that this should be used when instance), an answer was forged. Note that this should be used when
an answer is still provided, not when failure codes are returned an answer is still provided, not when failure codes are returned
instead. See Blocked(15), Censored (16), and Filtered (17) for use instead. See Blocked(15), Censored (16), and Filtered (17) for use
when returning other response codes. when returning other response codes.
3.6. Extended DNS Error Code 5 - DNSSEC Indeterminate 4.6. Extended DNS Error Code 5 - DNSSEC Indeterminate
The resolver attempted to perform DNSSEC validation, but validation The resolver attempted to perform DNSSEC validation, but validation
ended in the Indeterminate state [RFC4035]. ended in the Indeterminate state [RFC4035].
3.7. Extended DNS Error Code 6 - DNSSEC Bogus 4.7. Extended DNS Error Code 6 - DNSSEC Bogus
The resolver attempted to perform DNSSEC validation, but validation The resolver attempted to perform DNSSEC validation, but validation
ended in the Bogus state. ended in the Bogus state.
3.8. Extended DNS Error Code 7 - Signature Expired 4.8. Extended DNS Error Code 7 - Signature Expired
The resolver attempted to perform DNSSEC validation, but no The resolver attempted to perform DNSSEC validation, but no
signatures are presently valid and some (often all) are expired. signatures are presently valid and some (often all) are expired.
3.9. Extended DNS Error Code 8 - Signature Not Yet Valid 4.9. Extended DNS Error Code 8 - Signature Not Yet Valid
The resolver attempted to perform DNSSEC validation, but but no The resolver attempted to perform DNSSEC validation, but but no
signatures are presently valid and at least some are not yet valid. signatures are presently valid and at least some are not yet valid.
3.10. Extended DNS Error Code 9 - DNSKEY Missing 4.10. Extended DNS Error Code 9 - DNSKEY Missing
A DS record existed at a parent, but no supported matching DNSKEY A DS record existed at a parent, but no supported matching DNSKEY
record could be found for the child. record could be found for the child.
3.11. Extended DNS Error Code 10 - RRSIGs Missing 4.11. Extended DNS Error Code 10 - RRSIGs Missing
The resolver attempted to perform DNSSEC validation, but no RRSIGs The resolver attempted to perform DNSSEC validation, but no RRSIGs
could be found for at least one RRset where RRSIGs were expected. could be found for at least one RRset where RRSIGs were expected.
3.12. Extended DNS Error Code 11 - No Zone Key Bit Set 4.12. Extended DNS Error Code 11 - No Zone Key Bit Set
The resolver attempted to perform DNSSEC validation, but no Zone Key The resolver attempted to perform DNSSEC validation, but no Zone Key
Bit was set in a DNSKEY. Bit was set in a DNSKEY.
3.13. Extended DNS Error Code 12 - NSEC Missing 4.13. Extended DNS Error Code 12 - NSEC Missing
The resolver attempted to perform DNSSEC validation, but the The resolver attempted to perform DNSSEC validation, but the
requested data was missing and a covering NSEC or NSEC3 was not requested data was missing and a covering NSEC or NSEC3 was not
provided. provided.
3.14. Extended DNS Error Code 13 - Cached Error 4.14. Extended DNS Error Code 13 - Cached Error
The resolver is returning the SERVFAIL RCODE from its cache. The resolver is returning the SERVFAIL RCODE from its cache.
3.15. Extended DNS Error Code 14 - Not Ready 4.15. Extended DNS Error Code 14 - Not Ready
The server is unable to answer the query as it is not fully The server is unable to answer the query as it is not fully
functional (yet). functional (yet).
3.16. Extended DNS Error Code 15 - Blocked 4.16. Extended DNS Error Code 15 - Blocked
The server is unable to respond to the request because the domain is The server is unable to respond to the request because the domain is
blacklisted due to an internal security policy imposed by the blacklisted due to an internal security policy imposed by the
operator of the server being directly talked to. operator of the server being directly talked to.
3.17. Extended DNS Error Code 16 - Censored 4.17. Extended DNS Error Code 16 - Censored
The server is unable to respond to the request because the domain is The server is unable to respond to the request because the domain is
blacklisted by a security policy imposed upon the server being talked blacklisted by a security policy imposed upon the server being talked
to by an external requirement. Note that how the imposed policy is to by an external requirement. Note that how the imposed policy is
applied is irrelevant (in-band DNS filtering, court order, etc). applied is irrelevant (in-band DNS filtering, court order, etc).
3.18. Extended DNS Error Code 17 - Filtered 4.18. Extended DNS Error Code 17 - Filtered
The server is unable to respond to the request because the domain is The server is unable to respond to the request because the domain is
blacklisted as requested by the client. Functionally, this amounts blacklisted as requested by the client. Functionally, this amounts
to "you requested that we filter domains like this one." to "you requested that we filter domains like this one."
3.19. Extended DNS Error Code 18 - Prohibited 4.19. Extended DNS Error Code 18 - Prohibited
An authoritative or recursive resolver that receives a query from an An authoritative or recursive resolver that receives a query from an
"unauthorized" client can annotate its REFUSED message with this "unauthorized" client can annotate its REFUSED message with this
code. Examples of "unauthorized" clients are recursive queries from code. Examples of "unauthorized" clients are recursive queries from
IP addresses outside the network, blacklisted IP addresses, local IP addresses outside the network, blacklisted IP addresses, local
policy, etc. policy, etc.
3.20. Extended DNS Error Code 19 - Stale NXDOMAIN Answer 4.20. Extended DNS Error Code 19 - Stale NXDOMAIN Answer
The resolver was unable to resolve an answer within its configured The resolver was unable to resolve an answer within its configured
time limits and decided to answer with a previously cached NXDOMAIN time limits and decided to answer with a previously cached NXDOMAIN
answer instead of answering with an error. This is may be caused, answer instead of answering with an error. This is may be caused,
for example, by problems communicating with an authoritative server, for example, by problems communicating with an authoritative server,
possibly as result of a DoS attack against another network. possibly as result of a DoS attack against another network.
3.21. Extended DNS Error Code 20 - Not Authoritative 4.21. Extended DNS Error Code 20 - Not Authoritative
An authoritative server that receives a query (with the RD bit clear, An authoritative server that receives a query (with the RD bit clear,
or when not configured for recursion) for a domain for which it is or when not configured for recursion) for a domain for which it is
not authoritative SHOULD include this EDE code in the REFUSED not authoritative SHOULD include this EDE code in the REFUSED
response. A resolver that receives a query (with the RD bit clear) response. A resolver that receives a query (with the RD bit clear)
SHOULD include this EDE code in the REFUSED response. SHOULD include this EDE code in the REFUSED response.
3.22. Extended DNS Error Code 21 - Not Supported 4.22. Extended DNS Error Code 21 - Not Supported
The requested operation or query is not supported as its use has been The requested operation or query is not supported as its use has been
deprecated. deprecated.
3.23. Extended DNS Error Code 22 - No Reachable Authority 4.23. Extended DNS Error Code 22 - No Reachable Authority
The resolver could not reach any of the authoritative name servers The resolver could not reach any of the authoritative name servers
(or they refused to reply). (or they refused to reply).
3.24. Extended DNS Error Code 23 - Network Error 4.24. Extended DNS Error Code 23 - Network Error
An unrecoverable error occurred while communicating with another An unrecoverable error occurred while communicating with another
server. server.
3.25. Extended DNS Error Code 24 - Invalid Data 4.25. Extended DNS Error Code 24 - Invalid Data
An authoritative server that cannot answer with data for a zone it is An authoritative server that cannot answer with data for a zone it is
otherwise configured to support. This may occur because its most otherwise configured to support. This may occur because its most
recent zone is too old, or has expired, for example. recent zone is too old, or has expired, for example.
4. IANA Considerations 5. IANA Considerations
4.1. A New Extended DNS Error Code EDNS Option 5.1. A New Extended DNS Error Code EDNS Option
This document defines a new EDNS(0) option, entitled "Extended DNS This document defines a new EDNS(0) option, entitled "Extended DNS
Error", assigned a value of TBD1 from the "DNS EDNS0 Option Codes Error", assigned a value of TBD1 from the "DNS EDNS0 Option Codes
(OPT)" registry [to be removed upon publication: (OPT)" registry [to be removed upon publication:
[http://www.iana.org/assignments/dns-parameters/dns- [http://www.iana.org/assignments/dns-parameters/dns-
parameters.xhtml#dns-parameters-11] parameters.xhtml#dns-parameters-11]
Value Name Status Reference Value Name Status Reference
----- ---------------- ------ ------------------ ----- ---------------- ------ ------------------
TBD Extended DNS Error TBD [ This document ] TBD Extended DNS Error TBD [ This document ]
4.2. New Registry Table for Extended DNS Error Codes 5.2. New Registry Table for Extended DNS Error Codes
This document defines a new IANA registry table, where the index This document defines a new IANA registry table, where the index
value is the INFO-CODE from the "Extended DNS Error" EDNS option value is the INFO-CODE from the "Extended DNS Error" EDNS option
defined in this document. The IANA is requested to create and defined in this document. The IANA is requested to create and
maintain this "Extended DNS Error" codes registry. The code-point maintain this "Extended DNS Error" codes registry. The code-point
space for the INFO-CODE index is to be broken into 3 ranges: space for the INFO-CODE index is to be broken into 2 ranges:
o 0 - 32767: Expert Review [RFC2434]. o 0 - 49151: First come, first served.
o 32768 - 49151: First come, first served. o 49152 - 65280: Private use.
o 49152 - 65535: Experimental / Private use.
A starting set of entries, based on the contents of this document, is A starting set of entries, based on the contents of this document, is
as follows: as follows:
INFO-CODE: 0 INFO-CODE: 0
Purpose: Other Error Purpose: Other Error
Reference: Section 3.1 Reference: Section 4.1
INFO-CODE: 1 INFO-CODE: 1
Purpose: Unsupported DNSKEY Algorithm Purpose: Unsupported DNSKEY Algorithm
Reference: Section 3.2 Reference: Section 4.2
INFO-CODE: 2 INFO-CODE: 2
Purpose: Unsupported DS Digest Type Purpose: Unsupported DS Digest Type
Reference: Section 3.3 Reference: Section 4.3
INFO-CODE: 3 INFO-CODE: 3
Purpose: Stale Answer Purpose: Stale Answer
Reference: Section 3.4, [I-D.ietf-dnsop-serve-stale] Reference: Section 4.4, [I-D.ietf-dnsop-serve-stale]
INFO-CODE: 4 INFO-CODE: 4
Purpose: Forged Answer Purpose: Forged Answer
Reference: Section 3.5 Reference: Section 4.5
INFO-CODE: 5 INFO-CODE: 5
Purpose: DNSSEC Indeterminate Purpose: DNSSEC Indeterminate
Reference: Section 3.6 Reference: Section 4.6
INFO-CODE: 6 INFO-CODE: 6
Purpose: DNSSEC Bogus Purpose: DNSSEC Bogus
Reference: Section 3.7 Reference: Section 4.7
INFO-CODE: 7 INFO-CODE: 7
Purpose: Signature Expired Purpose: Signature Expired
Reference: Section 3.8 Reference: Section 4.8
INFO-CODE: 8 INFO-CODE: 8
Purpose: Signature Not Yet Valid Purpose: Signature Not Yet Valid
Reference: Section 3.9 Reference: Section 4.9
INFO-CODE: 9 INFO-CODE: 9
Purpose: DNSKEY Missing Purpose: DNSKEY Missing
Reference: Section 3.10 Reference: Section 4.10
INFO-CODE: 10 INFO-CODE: 10
Purpose: RRSIGs Missing Purpose: RRSIGs Missing
Reference: Section 3.11 Reference: Section 4.11
INFO-CODE: 11 INFO-CODE: 11
Purpose: No Zone Key Bit Set Purpose: No Zone Key Bit Set
Reference: Section 3.12 Reference: Section 4.12
INFO-CODE: 12 INFO-CODE: 12
Purpose: NSEC Missing Purpose: NSEC Missing
Reference: Section 3.13 Reference: Section 4.13
INFO-CODE: 13 INFO-CODE: 13
Purpose: Cached Error Purpose: Cached Error
Reference: Section 3.14 Reference: Section 4.14
INFO-CODE: 14 INFO-CODE: 14
Purpose: Not Ready. Purpose: Not Ready.
Reference: Section 3.15 Reference: Section 4.15
INFO-CODE: 15 INFO-CODE: 15
Purpose: Blocked Purpose: Blocked
Reference: Section 3.16 Reference: Section 4.16
INFO-CODE: 16 INFO-CODE: 16
Purpose: Censored Purpose: Censored
Reference: Section 3.17 Reference: Section 4.17
INFO-CODE: 17 INFO-CODE: 17
Purpose: Filtered Purpose: Filtered
Reference: Section 3.18 Reference: Section 4.18
INFO-CODE: 18 INFO-CODE: 18
Purpose: Prohibited Purpose: Prohibited
Reference: Section 3.19 Reference: Section 4.19
INFO-CODE: 19 INFO-CODE: 19
Purpose: Stale NXDomain Answer Purpose: Stale NXDomain Answer
Reference: Section 3.20 Reference: Section 4.20
INFO-CODE: 20 INFO-CODE: 20
Purpose: Not Authoritative Purpose: Not Authoritative
Reference: Section 3.21 Reference: Section 4.21
INFO-CODE: 21 INFO-CODE: 21
Purpose: Not Supported Purpose: Not Supported
Reference: Section 3.22 Reference: Section 4.22
INFO-CODE: 22 INFO-CODE: 22
Purpose: No Reachable Authority Purpose: No Reachable Authority
Reference: Section 3.23 Reference: Section 4.23
INFO-CODE: 23 INFO-CODE: 23
Purpose: Network Error Purpose: Network Error
Reference: Section 3.24 Reference: Section 4.24
INFO-CODE: 24 INFO-CODE: 24
Purpose: Invalid Data Purpose: Invalid Data
Reference: Section 3.25 Reference: Section 4.25
5. Security Considerations 6. Security Considerations
Though DNSSEC continues to be deployed, unfortunately a significant Though DNSSEC continues to be deployed, unfortunately a significant
number of clients (~11% according to [GeoffValidation]) that receive number of clients (~11% according to [GeoffValidation]) that receive
a SERVFAIL from a validating resolver because of a DNSSEC validaion a SERVFAIL from a validating resolver because of a DNSSEC validaion
issue will simply ask the next (potentially non-validating) resolver issue will simply ask the next (potentially non-validating) resolver
in their list, and thus don't get any of the protections which DNSSEC in their list, and thus don't get any of the protections which DNSSEC
should provide. should provide.
This information is unauthenticated information, and an attacker (e.g This information is unauthenticated information, and an attacker (e.g
a MITM or malicious recursive server) could insert an extended error a MITM or malicious recursive server) could insert an extended error
response into already untrusted data -- ideally clients and resolvers response into already untrusted data -- ideally clients and resolvers
would not trust any unauthenticated information, but until we live in would not trust any unauthenticated information, but until we live in
an era where all DNS answers are authenticated via DNSSEC or other an era where all DNS answers are authenticated via DNSSEC or other
mechanisms [RFC2845] [RFC8094], there are some tradeoffs. As an mechanisms [RFC2845] [RFC8094], there are some tradeoffs. As an
example, an attacker who is able to insert the DNSSEC Bogus Extended example, an attacker who is able to insert the DNSSEC Bogus Extended
Error into a packet could instead simply reply with a fictitious Error into a packet could instead simply reply with a fictitious
address (A or AAAA) record. Note that DNS Response Codes also address (A or AAAA) record. Note that DNS Response Codes also
contain no authentication and can be just as easily manipulated. contain no authentication and can be just as easily manipulated.
6. Acknowledgements 7. Acknowledgements
The authors wish to thank Joe Abley, Mark Andrews, Tim April, The authors wish to thank Joe Abley, Mark Andrews, Tim April,
Vittorio Bertola, Stephane Bortzmeyer, Vladimir Cunat, Ralph Dolmans, Vittorio Bertola, Stephane Bortzmeyer, Vladimir Cunat, Ralph Dolmans,
Peter DeVries, Peter van Dijk, Mats Dufberg, Donald Eastlake, Bob Peter DeVries, Peter van Dijk, Mats Dufberg, Donald Eastlake, Bob
Harold, Paul Hoffman, Geoff Huston, Shane Kerr, Edward Lewis, Carlos Harold, Paul Hoffman, Geoff Huston, Shane Kerr, Edward Lewis, Carlos
M. Martinez, George Michelson, Eric Orth, Michael Sheldon, Puneet M. Martinez, George Michelson, Eric Orth, Michael Sheldon, Puneet
Sood, Petr Spacek, Ondrej Sury, John Todd, Loganaden Velvindron, and Sood, Petr Spacek, Ondrej Sury, John Todd, Loganaden Velvindron, and
Paul Vixie. They also vaguely remember discussing this with a number Paul Vixie. They also vaguely remember discussing this with a number
of people over the years, but have forgotten who all they were -- if of people over the years, but have forgotten who all they were -- if
you were one of them, and are not listed, please let us know and you were one of them, and are not listed, please let us know and
we'll acknowledge you. we'll acknowledge you.
One author also wants to thank the band "Infected Mushroom" for One author also wants to thank the band "Infected Mushroom" for
providing a good background soundtrack (and to see if he can get away providing a good background soundtrack (and to see if he can get away
with this in an RFC!) Another author would like to thank the band with this in an RFC!) Another author would like to thank the band
"Mushroom Infectors". This was funny at the time we wrote it, but we "Mushroom Infectors". This was funny at the time we wrote it, but we
cannot remember why... cannot remember why...
7. References 8. References
7.1. Normative References 8.1. Normative References
[I-D.ietf-dnsop-serve-stale] [I-D.ietf-dnsop-serve-stale]
Lawrence, D., Kumari, W., and P. Sood, "Serving Stale Data Lawrence, D., Kumari, W., and P. Sood, "Serving Stale Data
to Improve DNS Resiliency", draft-ietf-dnsop-serve- to Improve DNS Resiliency", draft-ietf-dnsop-serve-
stale-08 (work in progress), September 2019. stale-10 (work in progress), December 2019.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, <https://www.rfc- DOI 10.17487/RFC2119, March 1997,
editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 2434,
DOI 10.17487/RFC2434, October 1998, <https://www.rfc-
editor.org/info/rfc2434>.
[RFC2671] Vixie, P., "Extension Mechanisms for DNS (EDNS0)",
RFC 2671, DOI 10.17487/RFC2671, August 1999,
<https://www.rfc-editor.org/info/rfc2671>.
[RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S. [RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Protocol Modifications for the DNS Security Rose, "Protocol Modifications for the DNS Security
Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005, Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005,
<https://www.rfc-editor.org/info/rfc4035>. <https://www.rfc-editor.org/info/rfc4035>.
[RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms [RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms
for DNS (EDNS(0))", STD 75, RFC 6891, for DNS (EDNS(0))", STD 75, RFC 6891,
DOI 10.17487/RFC6891, April 2013, <https://www.rfc- DOI 10.17487/RFC6891, April 2013,
editor.org/info/rfc6891>. <https://www.rfc-editor.org/info/rfc6891>.
7.2. Informative References 8.2. Informative References
[GeoffValidation] [GeoffValidation]
IANA, "A quick review of DNSSEC Validation in today's APNIC, G. H., "A quick review of DNSSEC Validation in
Internet", June 2016, <http://www.potaroo.net/ today's Internet", June 2016, <http://www.potaroo.net/
presentations/2016-06-27-dnssec.pdf>. presentations/2016-06-27-dnssec.pdf>.
[RFC2845] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B. [RFC2845] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B.
Wellington, "Secret Key Transaction Authentication for DNS Wellington, "Secret Key Transaction Authentication for DNS
(TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000, (TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000,
<https://www.rfc-editor.org/info/rfc2845>. <https://www.rfc-editor.org/info/rfc2845>.
[RFC8094] Reddy, T., Wing, D., and P. Patil, "DNS over Datagram [RFC8094] Reddy, T., Wing, D., and P. Patil, "DNS over Datagram
Transport Layer Security (DTLS)", RFC 8094, Transport Layer Security (DTLS)", RFC 8094,
DOI 10.17487/RFC8094, February 2017, <https://www.rfc- DOI 10.17487/RFC8094, February 2017,
editor.org/info/rfc8094>. <https://www.rfc-editor.org/info/rfc8094>.
Authors' Addresses Authors' Addresses
Warren Kumari Warren Kumari
Google Google
1600 Amphitheatre Parkway 1600 Amphitheatre Parkway
Mountain View, CA 94043 Mountain View, CA 94043
US US
Email: warren@kumari.net Email: warren@kumari.net
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