--- 1/draft-ietf-dnsop-extended-error-04.txt 2019-03-11 15:20:02.281908587 -0700 +++ 2/draft-ietf-dnsop-extended-error-05.txt 2019-03-11 15:20:03.061927689 -0700 @@ -1,25 +1,25 @@ Network Working Group W. Kumari Internet-Draft Google Intended status: Standards Track E. Hunt -Expires: July 11, 2019 ISC +Expires: September 12, 2019 ISC R. Arends ICANN W. Hardaker USC/ISI D. Lawrence Oracle + Dyn - January 07, 2019 + March 11, 2019 Extended DNS Errors - draft-ietf-dnsop-extended-error-04 + draft-ietf-dnsop-extended-error-05 Abstract This document defines an extensible method to return additional information about the cause of DNS errors. Though created primarily to extend SERVFAIL to provide additional information about the cause of DNS and DNSSEC failures, the Extended DNS Errors option defined in this document allows all response types to contain extended error information. @@ -31,80 +31,93 @@ 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 http://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 July 11, 2019. + This Internet-Draft will expire on September 12, 2019. Copyright Notice Copyright (c) 2019 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 (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction and background . . . . . . . . . . . . . . . . . 3 - 1.1. Requirements notation . . . . . . . . . . . . . . . . . . 3 - 2. Extended Error EDNS0 option format . . . . . . . . . . . . . 3 - 3. Use of the Extended DNS Error option . . . . . . . . . . . . 4 + 1.1. Requirements notation . . . . . . . . . . . . . . . . . . 4 + 2. Extended Error EDNS0 option format . . . . . . . . . . . . . 4 + 3. Use of the Extended DNS Error option . . . . . . . . . . . . 5 3.1. The R (Retry) flag . . . . . . . . . . . . . . . . . . . 5 3.2. The RESPONSE-CODE field . . . . . . . . . . . . . . . . . 5 - 3.3. The INFO-CODE field . . . . . . . . . . . . . . . . . . . 5 - 3.4. The EXTRA-TEXT field . . . . . . . . . . . . . . . . . . 5 - 4. Defined Extended DNS Errors . . . . . . . . . . . . . . . . . 5 + 3.3. The INFO-CODE field . . . . . . . . . . . . . . . . . . . 6 + 3.4. The EXTRA-TEXT field . . . . . . . . . . . . . . . . . . 6 + 4. Defined Extended DNS Errors . . . . . . . . . . . . . . . . . 6 4.1. INFO-CODEs for use with RESPONSE-CODE: NOERROR(0) . . . . 6 4.1.1. NOERROR Extended DNS Error Code 1 - Unsupported DNSKEY Algorithm . . . . . . . . . . . . . . . . . . 6 4.1.2. NOERROR Extended DNS Error Code 2 - Unsupported DS Algorithm . . . . . . . . . . . . . . . . . . . . 6 - 4.2. INFO-CODEs for use with RESPONSE-CODE: SERVFAIL(2) . . . 6 - 4.2.1. SERVFAIL Extended DNS Error Code 1 - DNSSEC Bogus . . 6 - 4.2.2. SERVFAIL Extended DNS Error Code 2 - DNSSEC - Indeterminate . . . . . . . . . . . . . . . . . . . . 6 - 4.2.3. SERVFAIL Extended DNS Error Code 3 - Signature - Expired . . . . . . . . . . . . . . . . . . . . . . . 6 - 4.2.4. SERVFAIL Extended DNS Error Code 4 - Signature Not - Yet Valid . . . . . . . . . . . . . . . . . . . . . . 6 - 4.2.5. SERVFAIL Extended DNS Error Code 5 - DNSKEY missing . 6 - 4.2.6. SERVFAIL Extended DNS Error Code 6 - RRSIGs missing . 7 - 4.2.7. SERVFAIL Extended DNS Error Code 7 - No Zone Key Bit - Set . . . . . . . . . . . . . . . . . . . . . . . . . 7 - 4.3. INFO-CODEs for use with RESPONSE-CODE: REFUSED(5) . . . . 7 - 4.3.1. REFUSED Extended DNS Error Code 1 - Lame . . . . . . 7 - 4.3.2. REFUSED Extended DNS Error Code 2 - Prohibited . . . 7 - 4.4. INFO-CODEs for use with RESPONSE-CODE: NXDOMAIN(3) . . . 7 - 4.4.1. NXDOMAIN Extended DNS Error Code 1 - Blocked . . . . 7 - 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 - 5.1. new Extended Error Code EDNS Option . . . . . . . . . . . 7 - 5.2. New Extended Error Code EDNS Option . . . . . . . . . . . 8 - 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 - 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10 - 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 8.1. Normative References . . . . . . . . . . . . . . . . . . 10 - 8.2. Informative References . . . . . . . . . . . . . . . . . 10 - Appendix A. Changes / Author Notes. . . . . . . . . . . . . . . 11 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 + 4.1.3. INFO-CODEs for use with RESPONSE-CODE: NOERROR(3) . . 6 + 4.1.4. NOERROR Extended DNS Error Code 4 - Forged answer . . 7 + 4.1.5. SERVFAIL Extended DNS Error Code 5 - DNSSEC + Indeterminate . . . . . . . . . . . . . . . . . . . . 7 + 4.2. INFO-CODEs for use with RESPONSE-CODE: SERVFAIL(2) . . . 7 + 4.2.1. SERVFAIL Extended DNS Error Code 1 - DNSSEC Bogus . . 7 + 4.2.2. SERVFAIL Extended DNS Error Code 2 - Signature + Expired . . . . . . . . . . . . . . . . . . . . . . . 7 + 4.2.3. SERVFAIL Extended DNS Error Code 3 - Signature Not + Yet Valid . . . . . . . . . . . . . . . . . . . . . . 7 + 4.2.4. SERVFAIL Extended DNS Error Code 4 - DNSKEY missing . 7 + 4.2.5. SERVFAIL Extended DNS Error Code 5 - RRSIGs missing . 7 + 4.2.6. SERVFAIL Extended DNS Error Code 6 - No Zone Key Bit + Set . . . . . . . . . . . . . . . . . . . . . . . . . 8 + 4.2.7. SERVFAIL Extended DNS Error Code 7 - No + Reachable Authority . . . . . . . . . . . . . . . . . 8 + 4.2.8. SERVFAIL Extended DNS Error Code 8 - NSEC Missing . . 8 + 4.2.9. SERVFAIL Extended DNS Error Code 9 - Cached Error . . 8 + 4.2.10. SERVFAIL Extended DNS Error Code 10 - Not Ready . . . 8 + 4.3. INFO-CODEs for use with RESPONSE-CODE: NOTIMP(4) . . . . 8 + 4.3.1. NOTIMP Extended DNS Error Code 1 - Deprecated . . . . 8 + 4.4. INFO-CODEs for use with RESPONSE-CODE: REFUSED(5) . . . . 8 + 4.4.1. REFUSED Extended DNS Error Code 1 - Lame . . . . . . 8 + 4.4.2. REFUSED Extended DNS Error Code 2 - Prohibited . . . 9 + 4.5. INFO-CODEs for use with RESPONSE-CODE: NXDOMAIN(3) . . . 9 + 4.5.1. NXDOMAIN Extended DNS Error Code 1 - Blocked . . . . 9 + 4.6. INFO-CODEs for use with RESPONSE-CODE: NXDOMAIN(3) . . . 9 + 4.6.1. NXDOMAIN Extended DNS Error Code 2 - Censored . . . . 9 + 4.7. INFO-CODEs for use with RESPONSE-CODE: NXDOMAIN(3) . . . 9 + 4.7.1. NXDOMAIN Extended DNS Error Code 3 - Stale Answer . . 9 + 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 + 5.1. A New Extended Error Code EDNS Option . . . . . . . . . . 9 + 5.2. New Double-Index Registry Table for Extended Error Codes 10 + 6. Security Considerations . . . . . . . . . . . . . . . . . . . 12 + 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13 + 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 + 8.1. Normative References . . . . . . . . . . . . . . . . . . 13 + 8.2. Informative References . . . . . . . . . . . . . . . . . 13 + Appendix A. Changes / Author Notes. . . . . . . . . . . . . . . 14 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 1. Introduction and background There are many reasons that a DNS query may fail, some of them transient, some permanent; some can be resolved by querying another server, some are likely best handled by stopping resolution. Unfortunately, the error signals that a DNS server can return are very limited, and are not very expressive. This means that applications and resolvers often have to "guess" at what the issue is - e.g. was the answer marked REFUSED because of a lame delegation, or @@ -123,20 +136,26 @@ returned again, and the user gets an (largely) incomprehensible error message; or the next resolver is not a validating resolver, and the user is returned a potentially harmful result. This document specifies a mechanism to extend (or annotate) DNS errors to provide additional information about the cause of the error. When properly authenticated, this information can be used by the resolver to make a decision regarding whether or not to retry or it can be used or by technical users attempting to debug issues. + These extended error codes are specially useful when received by + resolvers, to return to stub resolvers or to downstream resolvers. + Authoritative servers MAY parse and use them, but most error codes + would make no sense for them. Authoritative servers may need to + generate extended error codes though. + 1.1. Requirements notation The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 2. Extended Error EDNS0 option format This draft uses an EDNS0 ([RFC2671]) option to include Extended DNS Error (EDE) information in DNS messages. The option is structured as @@ -161,72 +180,81 @@ o OPTION-CODE, 2 octets (defined in [RFC6891]), for EDE is TBD. [RFC Editor: change TBD to the proper code once assigned by IANA.] o OPTION-LENGTH, 2 octets ((defined in [RFC6891]) contains the length of the payload (everything after OPTION-LENGTH) in octets and should be 4 plus the length of the EXTRA-TEXT section (which may be a zero-length string). o The RETRY flag, 1 bit; the RETRY bit (R) indicates a flag defined for use in this specification. o The RESERVED bits, 15 bits: these bits are reserved for future use, potentially as additional flags. The RESERVED bits MUST be - set to 0 by the sender and SHOULD be ignored by the receiver. + set to 0 by the sender and MUST be ignored by the receiver. + o RESPONSE-CODE, 4 bits. o INFO-CODE, 12-bits. o EXTRA-TEXT, a variable length, UTF-8 encoded, text field that may hold additional textual information. 3. Use of the Extended DNS Error option The Extended DNS Error (EDE) is an EDNS option. It can be included in any response (SERVFAIL, NXDOMAIN, REFUSED, etc) to a query that - includes an EDNS option. This document includes a set of initial - codepoints (and requests to the IANA to add them to the registry), - but is extensible via the IANA registry to allow additional error and - information codes to be defined in the future. + includes OPT Pseudo-RR [RFC6891]. This document includes a set of + initial codepoints (and requests to the IANA to add them to the + registry), but is extensible via the IANA registry to allow + additional error and information codes to be defined in the future. The fields of the Extended DNS Error option are defined further in the following sub-sections. 3.1. The R (Retry) flag The R (Retry) flag provides a hint as to what the receiver may want to do with this annotated error. Specifically, the R (or Retry) flag provides a hint to the receiver that it should retry the query to another server. If the R bit is set (1), the sender believes that retrying the query may provide a successful answer next time; if the R bit is clear (0), the sender believes that the resolver should not ask another server. The mechanism is specifically designed to be extensible, and so implementations may receive EDE codes that it does not understand. The R flag allows implementations to make a decision as to what to do if it receives a response with an unknown code - retry or drop the query. Note that this flag is only a suggestion. Unless a - protective transport mechanism (like TSIG [RFC2845] or TLS [RFC8094]) - is used, the bit's value could have have been altered by a person-in- - the-middle. Receivers can choose to ignore this hint. See the - security considerations for additional considerations. + protective transport mechanism (like TSIG [RFC2845] or (D)TLS xref + target="RFC7858"/>, [RFC8094]) is used, the bit's value could have + have been altered by a person-in-the-middle. Receivers can choose to + ignore this hint. See the security considerations for additional + considerations. 3.2. The RESPONSE-CODE field This 4-bit value SHOULD be a copy of the RCODE from the primary DNS - packet. Multiple EDNS0/EDE records may be included in the response. - When including multiple EDNS0/EDE records in a response in order to - provide additional error information, other RESPONSE-CODEs MAY use a - different RCODE. + packet. RESPONSE-CODEs MAY use a different RCODE to provide + additional or better information. For example, multiple EDNS0/EDE + records may be included in the response and the supplemental EDNS0/ + EDE records may wish to include other RESPONSE-CODE values based on + communication results with other DNS servers. 3.3. The INFO-CODE field This 12-bit value provides the additional context for the RESPONSE- CODE value. This combination of the RESPONSE-CODE and the INFO-CODE serve as a joint-index into the IANA "Extended DNS Errors" registry. + Note to implementers: the combination of the RESPONSE-CODE and INFO- + CODE fits within a 16-bit field, allowing implementers the choice of + treating the combination as either two separate values, as defined in + this document, or as a single 16-bit integer as long as the results + are deterministic. + 3.4. The EXTRA-TEXT field The UTF-8-encoded, EXTRA-TEXT field may be zero-length, or may hold additional information useful to network operators. 4. Defined Extended DNS Errors This document defines some initial EDE codes. The mechanism is intended to be extensible, and additional code-points can be registered in the "Extended DNS Errors" registry. This document @@ -243,99 +271,166 @@ 4.1.1. NOERROR Extended DNS Error Code 1 - Unsupported DNSKEY Algorithm The resolver attempted to perform DNSSEC validation, but a DNSKEY RRSET contained only unknown algorithms. The R flag should be set. 4.1.2. NOERROR Extended DNS Error Code 2 - Unsupported DS Algorithm The resolver attempted to perform DNSSEC validation, but a DS RRSET contained only unknown algorithms. The R flag should be set. -4.2. INFO-CODEs for use with RESPONSE-CODE: SERVFAIL(2) +4.1.3. INFO-CODEs for use with RESPONSE-CODE: NOERROR(3) +4.1.3.1. NOERROR Extended DNS Error Code 3 - Stale Answer -4.2.1. SERVFAIL Extended DNS Error Code 1 - DNSSEC Bogus + The resolver was unable to resolve answer within its time limits and + decided to answer with a previously cached data instead of answering + with an error. This is typically caused by problems on authoritative + side, possibly as result of a DoS attack. The R flag should not be + set, since retrying is likely to create additional load without + yielding a more fresh answer. - The resolver attempted to perform DNSSEC validation, but validation - ended in the Bogus state. The R flag should not be set. +4.1.4. NOERROR Extended DNS Error Code 4 - Forged answer -4.2.2. SERVFAIL Extended DNS Error Code 2 - DNSSEC Indeterminate + For policy reasons (legal obligation, or malware filtering, for + instance), an answer was forged. The R flag should not be set. + +4.1.5. SERVFAIL Extended DNS Error Code 5 - DNSSEC Indeterminate The resolver attempted to perform DNSSEC validation, but validation ended in the Indeterminate state. The R flag should not be set. -4.2.3. SERVFAIL Extended DNS Error Code 3 - Signature Expired +4.2. INFO-CODEs for use with RESPONSE-CODE: SERVFAIL(2) - The resolver attempted to perform DNSSEC validation, but the - signature was expired. The R flag should not be set. +4.2.1. SERVFAIL Extended DNS Error Code 1 - DNSSEC Bogus -4.2.4. SERVFAIL Extended DNS Error Code 4 - Signature Not Yet Valid + The resolver attempted to perform DNSSEC validation, but validation + ended in the Bogus state. The R flag should not be set. + +4.2.2. SERVFAIL Extended DNS Error Code 2 - Signature Expired + + The resolver attempted to perform DNSSEC validation, a signature in + the validation chain was expired. The R flag should not be set. + +4.2.3. SERVFAIL Extended DNS Error Code 3 - Signature Not Yet Valid The resolver attempted to perform DNSSEC validation, but the signatures received were not yet valid. The R flag should not be set. -4.2.5. SERVFAIL Extended DNS Error Code 5 - DNSKEY missing +4.2.4. SERVFAIL Extended DNS Error Code 4 - DNSKEY missing - A DS record existed at a parent, but no DNSKEY record could be found - for the child. The R flag should not be set. + A DS record existed at a parent, but no supported matching DNSKEY + record could be found for the child. The R flag should not be set. -4.2.6. SERVFAIL Extended DNS Error Code 6 - RRSIGs missing +4.2.5. SERVFAIL Extended DNS Error Code 5 - RRSIGs missing The resolver attempted to perform DNSSEC validation, but no RRSIGs could be found for at least one RRset where RRSIGs were expected. -4.2.7. SERVFAIL Extended DNS Error Code 7 - No Zone Key Bit Set +4.2.6. SERVFAIL Extended DNS Error Code 6 - No Zone Key Bit Set The resolver attempted to perform DNSSEC validation, but no Zone Key Bit was set in a DNSKEY. -4.3. INFO-CODEs for use with RESPONSE-CODE: REFUSED(5) +4.2.7. SERVFAIL Extended DNS Error Code 7 - No Reachable Authority -4.3.1. REFUSED Extended DNS Error Code 1 - Lame + The resolver could not reach any of the authoritative name servers + (or they refused to reply). The R flag should be set. - An authoritative resolver that receives a query (with the RD bit - clear) for a domain for which it is not authoritative SHOULD include - this EDE code in the REFUSED response. Implementations should set - the R flag in this case (another nameserver might not be lame). +4.2.8. SERVFAIL Extended DNS Error Code 8 - NSEC Missing -4.3.2. REFUSED Extended DNS Error Code 2 - Prohibited + The resolver attempted to perform DNSSEC validation, but the + requested data was missing and a covering NSEC or NSEC3 was not + provided. The R flag should be set. + +4.2.9. SERVFAIL Extended DNS Error Code 9 - Cached Error + + The resolver has cached SERVFAIL for this query without additional + information. Th R flag should be set. + +4.2.10. SERVFAIL Extended DNS Error Code 10 - Not Ready + + The server is unable to answer the query as it is not fully up and + functional yet. + +4.3. INFO-CODEs for use with RESPONSE-CODE: NOTIMP(4) + +4.3.1. NOTIMP Extended DNS Error Code 1 - Deprecated + + The requested operation or query is not supported as its use has been + deprecated. Implementations should not set the R flag. (Retrying + request elsewhere is unlikely to yield any other results.) + +4.4. INFO-CODEs for use with RESPONSE-CODE: REFUSED(5) + +4.4.1. REFUSED Extended DNS Error Code 1 - Lame + + An authoritative server that receives a query (with the RD bit clear) + for a domain for which it is not authoritative SHOULD include this + EDE code in the SERVFAIL response. A resolver that receives a query + (with the RD bit clear) SHOULD include this EDE code in the REFUSED + response. Implementations should set the R flag in this case + (another nameserver or resolver might not be lame). + +4.4.2. REFUSED Extended DNS Error Code 2 - Prohibited An authoritative or recursive resolver that receives a query from an "unauthorized" client can annotate its REFUSED message with this code. Examples of "unauthorized" clients are recursive queries from IP addresses outside the network, blacklisted IP addresses, local policy, etc. Implementations SHOULD allow operators to define what to set the R flag to in this case. -4.4. INFO-CODEs for use with RESPONSE-CODE: NXDOMAIN(3) +4.5. INFO-CODEs for use with RESPONSE-CODE: NXDOMAIN(3) -4.4.1. NXDOMAIN Extended DNS Error Code 1 - Blocked +4.5.1. NXDOMAIN Extended DNS Error Code 1 - Blocked The resolver attempted to perfom a DNS query but the domain is - blacklisted due to a security policy. The R flag should not be set. + blacklisted due to a security policy implemented on the server being + directly talked to. The R flag should be set. + +4.6. INFO-CODEs for use with RESPONSE-CODE: NXDOMAIN(3) + +4.6.1. NXDOMAIN Extended DNS Error Code 2 - Censored + + The resolver attempted to perfom a DNS query but the domain was + blacklisted by a security policy imposed upon the server being talked + to. Note that how the imposed policy is applied is irrelevant (in- + band DNS somehow, court order, etc). The R flag should be set. + +4.7. INFO-CODEs for use with RESPONSE-CODE: NXDOMAIN(3) + +4.7.1. NXDOMAIN Extended DNS Error Code 3 - Stale Answer + + The resolver was unable to resolve answer within its time limits and + decided to answer with a previously cached NXDOMAIN answer instead of + answering with an error. This is typically caused by problems on + authoritative side, possibly as result of a DoS attack. The R flag + should not be set, since retrying is likely to create additional load + without yielding a more fresh answer. 5. IANA Considerations -5.1. new Extended Error Code EDNS Option +5.1. A New Extended Error Code EDNS Option This document defines a new EDNS(0) option, entitled "Extended DNS Error", assigned a value of TBD1 from the "DNS EDNS0 Option Codes (OPT)" registry [to be removed upon publication: [http://www.iana.org/assignments/dns-parameters/dns- parameters.xhtml#dns-parameters-11] Value Name Status Reference ----- ---------------- ------ ------------------ TBD Extended DNS Error TBD [ This document ] -5.2. New Extended Error Code EDNS Option +5.2. New Double-Index Registry Table for Extended Error Codes This document defines a new double-index IANA registry table, where the first index value is the RCODE value and the second index value is the INFO-CODE from the Extended DNS Error EDNS option defined in this document. The IANA is requested to create and maintain this "Extended DNS Error codes" registry. The codepoint space for each INFO-CODE index is to be broken into 3 ranges: o 0 - 3583: Specification required. o 3584 - 3839: First Come First Served. @@ -347,69 +442,109 @@ RESPONSE-CODE: 0 (NOERROR) INFO-CODE: 1 Purpose: Unsupported DNSKEY Reference: Section 4.1.1 RESPONSE-CODE: 0 (NOERROR) INFO-CODE: 2 Purpose: Unsupported DS Algorithm Reference: Section 4.1.2 + RESPONSE-CODE: 3 (NOERROR) + INFO-CODE: 3 + Purpose: Answering with stale/cached data + Reference: Section 4.1.3.1 + + RESPONSE-CODE: 0 (NOERROR) + INFO-CODE: 4 + Purpose: Forged answer + Reference: Section 4.1.4 + + RESPONSE-CODE: 0 (NOERROR) + INFO-CODE: 5 + Purpose: DNSSEC Indeterminate + Reference: Section 4.1.5 + RESPONSE-CODE: 2 (SERVFAIL) INFO-CODE: 1 Purpose: DNSSEC Bogus Reference: Section 4.2.1 RESPONSE-CODE: 2 (SERVFAIL) INFO-CODE: 2 - Purpose: DNSSEC Indeterminate + Purpose: Signature Expired Reference: Section 4.2.2 RESPONSE-CODE: 2 (SERVFAIL) INFO-CODE: 3 - Purpose: Signature Expired + Purpose: Signature Not Yet Valid Reference: Section 4.2.3 RESPONSE-CODE: 2 (SERVFAIL) INFO-CODE: 4 - Purpose: Signature Not Yet Valid + Purpose: DNSKEY missing Reference: Section 4.2.4 RESPONSE-CODE: 2 (SERVFAIL) INFO-CODE: 5 - Purpose: DNSKEY missing + Purpose: RRSIGs missing Reference: Section 4.2.5 RESPONSE-CODE: 2 (SERVFAIL) INFO-CODE: 6 - Purpose: RRSIGs missing + Purpose: No Zone Key Bit Set Reference: Section 4.2.6 RESPONSE-CODE: 2 (SERVFAIL) INFO-CODE: 7 - Purpose: No Zone Key Bit Set - Reference: Section 4.2.7 + Purpose: No NSEC records could be obtained + Reference: Section 4.2.8 + + RESPONSE-CODE: 2 (SERVFAIL) + INFO-CODE: 9 + Purpose: The SERVFAIL error comes from the cache + Reference: Section 4.2.9 + + RESPONSE-CODE: 2 (SERVFAIL) + INFO-CODE: 10 + Purpose: Not Ready. + Reference: Section 4.2.10 RESPONSE-CODE: 3 (NXDOMAIN) INFO-CODE: 1 Purpose: Blocked - Reference: Section 4.4.1 + Reference: Section 4.5.1 + + RESPONSE-CODE: 3 (NXDOMAIN) + INFO-CODE: 2 + Purpose: Censored + Reference: Section 4.6.1 + + RESPONSE-CODE: 3 (NXDOMAIN) + INFO-CODE: 3 + Purpose: Answering with stale/cached NXDOMAIN data + Reference: Section 4.7.1 + + RESPONSE-CODE: 4 (NOTIMP) + INFO-CODE: 1 + Purpose: + Reference: Section 4.4.2 RESPONSE-CODE: 5 (REFUSED) INFO-CODE: 1 Purpose: Lame - Reference: Section 4.3.1 + Reference: Section 4.4.1 RESPONSE-CODE: 5 (REFUSED) INFO-CODE: 2 Purpose: Prohibited - Reference: Section 4.3.2 + Reference: Section 4.4.2 6. Security Considerations Though DNSSEC continues to be deployed, unfortunately a significant number of clients (~11% according to [GeoffValidation]) that receive a SERVFAIL from a validating resolver because of a DNSSEC validaion issue will simply ask the next (potentially non-validating) resolver in their list, and thus don't get any of the protections which DNSSEC should provide. This is very similar to a kid asking his mother if he can have another cookie. When the mother says "No, it will ruin @@ -424,43 +559,49 @@ mechanisms, there are some tradeoffs. As an example, an attacker who is able to insert the DNSSEC Bogus Extended Error into a packet could instead simply reply with a fictitious address (A or AAAA) record. The R bit hint and extended error information are informational - implementations can choose how much to trust this information and validating resolvers / stubs may choose to put a different weight on it. 7. Acknowledgements - The authors wish to thank Joe Abley, Mark Andrews, Vladimir Cunat, - Peter DeVries, Peter van Dijk, Donald Eastlake, Bob Harold, Evan - Hunt, Geoff Huston, Shane Kerr, Edward Lewis, Carlos M. Martinez, - George Michelson, Petr Spacek, Ondrej Sury, Loganaden Velvindron, and - Paul Vixie. They also vaguely remember discussing this with a number - 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 - we'll acknowledge you. + The authors wish to thank Joe Abley, Mark Andrews, Stephane + Bortzmeyer, Vladimir Cunat, Peter DeVries, Peter van Dijk, Donald + Eastlake, Bob Harold, Evan Hunt, Geoff Huston, Shane Kerr, Edward + Lewis, Carlos M. Martinez, George Michelson, Michael Sheldon, Petr + Spacek, Ondrej Sury, Loganaden Velvindron, and Paul Vixie. They also + vaguely remember discussing this with a number 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 we'll acknowledge + you. I also want to thank the band "Infected Mushroom" for providing a good background soundtrack (and to see if I can get away with this!) Another author would like to thank the band "Mushroom Infectors". This was funny at the time we wrote it, but I cannot remember why... 8. References 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . + [RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms + for DNS (EDNS(0))", STD 75, RFC 6891, + DOI 10.17487/RFC6891, April 2013, . + 8.2. Informative References [GeoffValidation] IANA, "A quick review of DNSSEC Validation in today's Internet", June 2016, . [RFC2845] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B. Wellington, "Secret Key Transaction Authentication for DNS (TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000,