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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Obsolete informational reference (is this intentional?): RFC 2845 (Obsoleted by RFC 8945) Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group W. Kumari 3 Internet-Draft Google 4 Intended status: Standards Track E. Hunt 5 Expires: July 18, 2020 ISC 6 R. Arends 7 ICANN 8 W. Hardaker 9 USC/ISI 10 D. Lawrence 11 Oracle + Dyn 12 January 15, 2020 14 Extended DNS Errors 15 draft-ietf-dnsop-extended-error-14 17 Abstract 19 This document defines an extensible method to return additional 20 information about the cause of DNS errors. Though created primarily 21 to extend SERVFAIL to provide additional information about the cause 22 of DNS and DNSSEC failures, the Extended DNS Errors option defined in 23 this document allows all response types to contain extended error 24 information. Extended DNS Error information does not change the 25 processing of RCODEs. 27 Status of This Memo 29 This Internet-Draft is submitted in full conformance with the 30 provisions of BCP 78 and BCP 79. 32 Internet-Drafts are working documents of the Internet Engineering 33 Task Force (IETF). Note that other groups may also distribute 34 working documents as Internet-Drafts. The list of current Internet- 35 Drafts is at https://datatracker.ietf.org/drafts/current/. 37 Internet-Drafts are draft documents valid for a maximum of six months 38 and may be updated, replaced, or obsoleted by other documents at any 39 time. It is inappropriate to use Internet-Drafts as reference 40 material or to cite them other than as "work in progress." 42 This Internet-Draft will expire on July 18, 2020. 44 Copyright Notice 46 Copyright (c) 2020 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (https://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. Code Components extracted from this document must 55 include Simplified BSD License text as described in Section 4.e of 56 the Trust Legal Provisions and are provided without warranty as 57 described in the Simplified BSD License. 59 Table of Contents 61 1. Introduction and background . . . . . . . . . . . . . . . . . 3 62 1.1. Requirements notation . . . . . . . . . . . . . . . . . . 4 63 2. Extended DNS Error EDNS0 option format . . . . . . . . . . . 4 64 3. Extended DNS Error Processing . . . . . . . . . . . . . . . . 5 65 4. Defined Extended DNS Errors . . . . . . . . . . . . . . . . . 5 66 4.1. Extended DNS Error Code 0 - Other . . . . . . . . . . . . 6 67 4.2. Extended DNS Error Code 1 - 68 Unsupported DNSKEY Algorithm . . . . . . . . . . . . . . 6 69 4.3. Extended DNS Error Code 2 - Unsupported DS 70 Digest Type . . . . . . . . . . . . . . . . . . . . . . . 6 71 4.4. Extended DNS Error Code 3 - Stale Answer . . . . . . . . 6 72 4.5. Extended DNS Error Code 4 - Forged Answer . . . . . . . . 6 73 4.6. Extended DNS Error Code 5 - DNSSEC Indeterminate . . . . 6 74 4.7. Extended DNS Error Code 6 - DNSSEC Bogus . . . . . . . . 6 75 4.8. Extended DNS Error Code 7 - Signature Expired . . . . . . 6 76 4.9. Extended DNS Error Code 8 - Signature Not Yet Valid . . . 7 77 4.10. Extended DNS Error Code 9 - DNSKEY Missing . . . . . . . 7 78 4.11. Extended DNS Error Code 10 - RRSIGs Missing . . . . . . . 7 79 4.12. Extended DNS Error Code 11 - No Zone Key Bit Set . . . . 7 80 4.13. Extended DNS Error Code 12 - NSEC Missing . . . . . . . . 7 81 4.14. Extended DNS Error Code 13 - Cached Error . . . . . . . . 7 82 4.15. Extended DNS Error Code 14 - Not Ready . . . . . . . . . 7 83 4.16. Extended DNS Error Code 15 - Blocked . . . . . . . . . . 7 84 4.17. Extended DNS Error Code 16 - Censored . . . . . . . . . . 7 85 4.18. Extended DNS Error Code 17 - Filtered . . . . . . . . . . 8 86 4.19. Extended DNS Error Code 18 - Prohibited . . . . . . . . . 8 87 4.20. Extended DNS Error Code 19 - Stale NXDOMAIN Answer . . . 8 88 4.21. Extended DNS Error Code 20 - Not Authoritative . . . . . 8 89 4.22. Extended DNS Error Code 21 - Not Supported . . . . . . . 8 90 4.23. Extended DNS Error Code 22 - No Reachable Authority . . . 8 91 4.24. Extended DNS Error Code 23 - Network Error . . . . . . . 8 92 4.25. Extended DNS Error Code 24 - Invalid Data . . . . . . . . 9 93 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 94 5.1. A New Extended DNS Error Code EDNS Option . . . . . . . . 9 95 5.2. New Registry Table for Extended DNS Error Codes . . . . . 9 96 6. Security Considerations . . . . . . . . . . . . . . . . . . . 11 97 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12 98 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 99 8.1. Normative References . . . . . . . . . . . . . . . . . . 12 100 8.2. Informative References . . . . . . . . . . . . . . . . . 13 101 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 103 1. Introduction and background 105 There are many reasons that a DNS query may fail, some of them 106 transient, some permanent; some can be resolved by querying another 107 server, some are likely best handled by stopping resolution. 108 Unfortunately, the error signals that a DNS server can return are 109 very limited, and are not very expressive. This means that 110 applications and resolvers often have to "guess" at what the issue is 111 - e.g. was the answer marked REFUSED because of a lame delegation, or 112 because the nameserver is still starting up and loading zones? Is a 113 SERVFAIL a DNSSEC validation issue, or is the nameserver experiencing 114 some other failure? What error messages should be presented to the 115 user or logged under these conditions? 117 A good example of issues that would benefit by additional error 118 information are errors caused by DNSSEC validation issues. When a 119 stub resolver queries a name which is DNSSEC bogus (using a 120 validating resolver), the stub resolver receives only a SERVFAIL in 121 response. Unfortunately, the SERVFAIL Response Code (RCODE) is used 122 to signal many sorts of DNS errors, and so the stub resolvers only 123 option is to ask the next configured DNS resolver. The result of 124 trying the next resolver is one of two outcomes: either the next 125 resolver also validates, and a SERVFAIL is returned again or the next 126 resolver is not a validating resolver, and the user is returned a 127 potentially harmful result. With an Extended DNS Error (EDE) option 128 enclosed in the response message, the resolver is able to return a 129 more descriptive reason as to why any failures happened, or add 130 additional context to a message containing a NOERROR RCODE. 132 This document specifies a mechanism to extend DNS errors to provide 133 additional information about the cause of an error. These extended 134 DNS error codes described in this document and can be used by any 135 system that sends DNS queries and receives a response containing an 136 EDE option. Different codes are useful in different circumstances, 137 and thus different systems (stub resolvers, recursive resolvers, and 138 authoritative resolvers) might receive and use them. 140 This document does not allow or prohibit any particular extended 141 error codes and information to be matched with any particular RCODEs. 142 Some combinations of extended error codes and RCODEs may seem 143 nonsensical (such as resolver-specific extended error codes in 144 responses from authoritative servers), so systems interpreting the 145 extended error codes MUST NOT assume that a combination will make 146 sense. Receivers MUST be able to accept EDE codes and EXTRA-TEXT in 147 all messages, including those with a NOERROR RCODE. Applications 148 MUST continue to follow requirements from applicable specs on how to 149 process RCODEs no matter what EDE values is also received. Senders 150 MAY include more than one EDE option and receivers MUST be able to 151 accept (but not necessarily process or act on) multiple EDE options 152 in a DNS message. 154 1.1. Requirements notation 156 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 157 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 158 document are to be interpreted as described in [RFC2119]. 160 2. Extended DNS Error EDNS0 option format 162 This draft uses an EDNS0 ([RFC6891]) option to include Extended DNS 163 Error (EDE) information in DNS messages. The option is structured as 164 follows: 166 1 1 1 1 1 1 167 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 168 +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ 169 0: | OPTION-CODE | 170 +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ 171 2: | OPTION-LENGTH | 172 +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ 173 4: | INFO-CODE | 174 +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ 175 6: / EXTRA-TEXT ... / 176 +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ 178 Field definition details: 180 o OPTION-CODE, 2-octets/16-bits (defined in [RFC6891]]), for EDE is 181 TBD. [RFC Editor: change TBD to the proper code once assigned by 182 IANA.] 183 o OPTION-LENGTH, 2-octets/16-bits ((defined in [RFC6891]]) contains 184 the length of the payload (everything after OPTION-LENGTH) in 185 octets and should be 2 plus the length of the EXTRA-TEXT field 186 (which may be a zero-length string). 187 o INFO-CODE, 16-bits, which is the principal contribution of this 188 document. This 16-bit value, encoded in network (MSB) byte order, 189 provides the additional context for the RESPONSE-CODE of the DNS 190 message. The INFO-CODE serves as an index into the "Extended DNS 191 Errors" registry Section 5.1. 193 o EXTRA-TEXT, a variable length, UTF-8 encoded, text field that may 194 hold additional textual information. Note: EXTRA-TEXT may be zero 195 octets in length, indicating there is no EXTRA-TEXT included. 196 Care should be taken not to leak private information that an 197 observer would not otherwise have access to, such as account 198 numbers. 200 The Extended DNS Error (EDE) option can be included in any response 201 (SERVFAIL, NXDOMAIN, REFUSED, and even NOERROR, etc) to a query that 202 includes OPT Pseudo-RR [RFC6891]. This document includes a set of 203 initial codepoints (and requests to the IANA to add them to the 204 registry), but is extensible via the IANA registry to allow 205 additional error and information codes to be defined in the future. 207 3. Extended DNS Error Processing 209 When the response grows beyond the requestor's UDP payload size 210 [RFC6891], servers SHOULD truncate messages by dropping EDE options 211 before dropping other data from packets. Implementations SHOULD set 212 the truncation bit when dropping EDE options. Long EXTRA-TEXT fields 213 may trigger truncation, which is usually undesirable for the 214 supplemental nature of EDE. Implementers and operators creating EDE 215 options SHOULD avoid setting unnecessarily long EXTRA-TEXT contents 216 to avoid truncation. 218 When a resolver or forwarder receives an EDE option, whether or not 219 (and how) to pass along EDE information on to their original client 220 is implementation dependent. Implementations MAY choose to not 221 forward information, or they MAY choose to create a new EDE option(s) 222 that conveys the information encoded in the received EDE. When doing 223 so, the source of the error SHOULD be attributed in the EXTRA-TEXT 224 field, since an EDNS0 option received by the original client will be 225 perceived only to have come from the resolver or forwarder sending 226 it. 228 4. Defined Extended DNS Errors 230 This document defines some initial EDE codes. The mechanism is 231 intended to be extensible, and additional code-points can be 232 registered in the "Extended DNS Errors" registry Section 5.1. The 233 INFO-CODE from the EDE EDNS option is used to serve as an index into 234 the "Extended DNS Error" IANA registry, the initial values for which 235 are defined in the following sub-sections. 237 4.1. Extended DNS Error Code 0 - Other 239 The error in question falls into a category that does not match known 240 extended error codes. Implementations SHOULD include a EXTRA-TEXT 241 value to augment this error code with additional information. 243 4.2. Extended DNS Error Code 1 - Unsupported DNSKEY Algorithm 245 The resolver attempted to perform DNSSEC validation, but a DNSKEY 246 RRSET contained only unsupported DNSSEC algorithms. 248 4.3. Extended DNS Error Code 2 - Unsupported DS Digest Type 250 The resolver attempted to perform DNSSEC validation, but a DS RRSET 251 contained only unsupported Digest Types. 253 4.4. Extended DNS Error Code 3 - Stale Answer 255 The resolver was unable to resolve answer within its time limits and 256 decided to answer with previously cached data instead of answering 257 with an error. This is typically caused by problems communicating 258 with an authoritative serever, possibly as result of a DoS attack 259 against another network. 261 4.5. Extended DNS Error Code 4 - Forged Answer 263 For policy reasons (legal obligation, or malware filtering, for 264 instance), an answer was forged. Note that this should be used when 265 an answer is still provided, not when failure codes are returned 266 instead. See Blocked(15), Censored (16), and Filtered (17) for use 267 when returning other response codes. 269 4.6. Extended DNS Error Code 5 - DNSSEC Indeterminate 271 The resolver attempted to perform DNSSEC validation, but validation 272 ended in the Indeterminate state [RFC4035]. 274 4.7. Extended DNS Error Code 6 - DNSSEC Bogus 276 The resolver attempted to perform DNSSEC validation, but validation 277 ended in the Bogus state. 279 4.8. Extended DNS Error Code 7 - Signature Expired 281 The resolver attempted to perform DNSSEC validation, but no 282 signatures are presently valid and some (often all) are expired. 284 4.9. Extended DNS Error Code 8 - Signature Not Yet Valid 286 The resolver attempted to perform DNSSEC validation, but but no 287 signatures are presently valid and at least some are not yet valid. 289 4.10. Extended DNS Error Code 9 - DNSKEY Missing 291 A DS record existed at a parent, but no supported matching DNSKEY 292 record could be found for the child. 294 4.11. Extended DNS Error Code 10 - RRSIGs Missing 296 The resolver attempted to perform DNSSEC validation, but no RRSIGs 297 could be found for at least one RRset where RRSIGs were expected. 299 4.12. Extended DNS Error Code 11 - No Zone Key Bit Set 301 The resolver attempted to perform DNSSEC validation, but no Zone Key 302 Bit was set in a DNSKEY. 304 4.13. Extended DNS Error Code 12 - NSEC Missing 306 The resolver attempted to perform DNSSEC validation, but the 307 requested data was missing and a covering NSEC or NSEC3 was not 308 provided. 310 4.14. Extended DNS Error Code 13 - Cached Error 312 The resolver is returning the SERVFAIL RCODE from its cache. 314 4.15. Extended DNS Error Code 14 - Not Ready 316 The server is unable to answer the query as it is not fully 317 functional (yet). 319 4.16. Extended DNS Error Code 15 - Blocked 321 The server is unable to respond to the request because the domain is 322 blacklisted due to an internal security policy imposed by the 323 operator of the server being directly talked to. 325 4.17. Extended DNS Error Code 16 - Censored 327 The server is unable to respond to the request because the domain is 328 blacklisted by a security policy imposed upon the server being talked 329 to by an external requirement. Note that how the imposed policy is 330 applied is irrelevant (in-band DNS filtering, court order, etc). 332 4.18. Extended DNS Error Code 17 - Filtered 334 The server is unable to respond to the request because the domain is 335 blacklisted as requested by the client. Functionally, this amounts 336 to "you requested that we filter domains like this one." 338 4.19. Extended DNS Error Code 18 - Prohibited 340 An authoritative or recursive resolver that receives a query from an 341 "unauthorized" client can annotate its REFUSED message with this 342 code. Examples of "unauthorized" clients are recursive queries from 343 IP addresses outside the network, blacklisted IP addresses, local 344 policy, etc. 346 4.20. Extended DNS Error Code 19 - Stale NXDOMAIN Answer 348 The resolver was unable to resolve an answer within its configured 349 time limits and decided to answer with a previously cached NXDOMAIN 350 answer instead of answering with an error. This is may be caused, 351 for example, by problems communicating with an authoritative server, 352 possibly as result of a DoS attack against another network. 354 4.21. Extended DNS Error Code 20 - Not Authoritative 356 An authoritative server that receives a query (with the RD bit clear, 357 or when not configured for recursion) for a domain for which it is 358 not authoritative SHOULD include this EDE code in the REFUSED 359 response. A resolver that receives a query (with the RD bit clear) 360 SHOULD include this EDE code in the REFUSED response. 362 4.22. Extended DNS Error Code 21 - Not Supported 364 The requested operation or query is not supported as its use has been 365 deprecated. 367 4.23. Extended DNS Error Code 22 - No Reachable Authority 369 The resolver could not reach any of the authoritative name servers 370 (or they refused to reply). 372 4.24. Extended DNS Error Code 23 - Network Error 374 An unrecoverable error occurred while communicating with another 375 server. 377 4.25. Extended DNS Error Code 24 - Invalid Data 379 An authoritative server that cannot answer with data for a zone it is 380 otherwise configured to support. This may occur because its most 381 recent zone is too old, or has expired, for example. 383 5. IANA Considerations 385 5.1. A New Extended DNS Error Code EDNS Option 387 This document defines a new EDNS(0) option, entitled "Extended DNS 388 Error", assigned a value of TBD from the "DNS EDNS0 Option Codes 389 (OPT)" registry [to be removed upon publication: 390 [http://www.iana.org/assignments/dns-parameters/dns- 391 parameters.xhtml#dns-parameters-11] 393 Value Name Status Reference 394 ----- ---------------- ------ ------------------ 395 TBD Extended DNS Error TBD [ This document ] 397 5.2. New Registry Table for Extended DNS Error Codes 399 This document defines a new IANA registry table, where the index 400 value is the INFO-CODE from the "Extended DNS Error" EDNS option 401 defined in this document. The IANA is requested to create and 402 maintain this "Extended DNS Error" codes registry. The code-point 403 space for the INFO-CODE index is to be broken into 2 ranges: 405 o 0 - 49151: First come, first served. 406 o 49152 - 65280: Private use. 408 A starting set of entries, based on the contents of this document, is 409 as follows: 411 INFO-CODE: 0 412 Purpose: Other Error 413 Reference: Section 4.1 415 INFO-CODE: 1 416 Purpose: Unsupported DNSKEY Algorithm 417 Reference: Section 4.2 419 INFO-CODE: 2 420 Purpose: Unsupported DS Digest Type 421 Reference: Section 4.3 423 INFO-CODE: 3 424 Purpose: Stale Answer 425 Reference: Section 4.4, [I-D.ietf-dnsop-serve-stale] 427 INFO-CODE: 4 428 Purpose: Forged Answer 429 Reference: Section 4.5 431 INFO-CODE: 5 432 Purpose: DNSSEC Indeterminate 433 Reference: Section 4.6 435 INFO-CODE: 6 436 Purpose: DNSSEC Bogus 437 Reference: Section 4.7 439 INFO-CODE: 7 440 Purpose: Signature Expired 441 Reference: Section 4.8 443 INFO-CODE: 8 444 Purpose: Signature Not Yet Valid 445 Reference: Section 4.9 447 INFO-CODE: 9 448 Purpose: DNSKEY Missing 449 Reference: Section 4.10 451 INFO-CODE: 10 452 Purpose: RRSIGs Missing 453 Reference: Section 4.11 455 INFO-CODE: 11 456 Purpose: No Zone Key Bit Set 457 Reference: Section 4.12 459 INFO-CODE: 12 460 Purpose: NSEC Missing 461 Reference: Section 4.13 463 INFO-CODE: 13 464 Purpose: Cached Error 465 Reference: Section 4.14 467 INFO-CODE: 14 468 Purpose: Not Ready. 469 Reference: Section 4.15 471 INFO-CODE: 15 472 Purpose: Blocked 473 Reference: Section 4.16 475 INFO-CODE: 16 476 Purpose: Censored 477 Reference: Section 4.17 479 INFO-CODE: 17 480 Purpose: Filtered 481 Reference: Section 4.18 483 INFO-CODE: 18 484 Purpose: Prohibited 485 Reference: Section 4.19 487 INFO-CODE: 19 488 Purpose: Stale NXDomain Answer 489 Reference: Section 4.20 491 INFO-CODE: 20 492 Purpose: Not Authoritative 493 Reference: Section 4.21 495 INFO-CODE: 21 496 Purpose: Not Supported 497 Reference: Section 4.22 499 INFO-CODE: 22 500 Purpose: No Reachable Authority 501 Reference: Section 4.23 503 INFO-CODE: 23 504 Purpose: Network Error 505 Reference: Section 4.24 507 INFO-CODE: 24 508 Purpose: Invalid Data 509 Reference: Section 4.25 511 6. Security Considerations 513 Though DNSSEC continues to be deployed, unfortunately a significant 514 number of clients (~11% according to [GeoffValidation]) that receive 515 a SERVFAIL from a validating resolver because of a DNSSEC validaion 516 issue will simply ask the next (potentially non-validating) resolver 517 in their list, and thus don't get any of the protections which DNSSEC 518 should provide. 520 This information is unauthenticated information, and an attacker (e.g 521 a MITM or malicious recursive server) could insert an extended error 522 response into already untrusted data -- ideally clients and resolvers 523 would not trust any unauthenticated information, but until we live in 524 an era where all DNS answers are authenticated via DNSSEC or other 525 mechanisms [RFC2845] [RFC8094], there are some tradeoffs. As an 526 example, an attacker who is able to insert the DNSSEC Bogus Extended 527 Error into a packet could instead simply reply with a fictitious 528 address (A or AAAA) record. Note that DNS Response Codes also 529 contain no authentication and can be just as easily manipulated. 531 7. Acknowledgements 533 The authors wish to thank Joe Abley, Mark Andrews, Tim April, 534 Vittorio Bertola, Stephane Bortzmeyer, Vladimir Cunat, Ralph Dolmans, 535 Peter DeVries, Peter van Dijk, Mats Dufberg, Donald Eastlake, Bob 536 Harold, Paul Hoffman, Geoff Huston, Shane Kerr, Edward Lewis, Carlos 537 M. Martinez, George Michelson, Eric Orth, Michael Sheldon, Puneet 538 Sood, Petr Spacek, Ondrej Sury, John Todd, Loganaden Velvindron, and 539 Paul Vixie. They also vaguely remember discussing this with a number 540 of people over the years, but have forgotten who all they were -- if 541 you were one of them, and are not listed, please let us know and 542 we'll acknowledge you. 544 One author also wants to thank the band "Infected Mushroom" for 545 providing a good background soundtrack (and to see if he can get away 546 with this in an RFC!) Another author would like to thank the band 547 "Mushroom Infectors". This was funny at the time we wrote it, but we 548 cannot remember why... 550 8. References 552 8.1. Normative References 554 [I-D.ietf-dnsop-serve-stale] 555 Lawrence, D., Kumari, W., and P. Sood, "Serving Stale Data 556 to Improve DNS Resiliency", draft-ietf-dnsop-serve- 557 stale-10 (work in progress), December 2019. 559 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 560 Requirement Levels", BCP 14, RFC 2119, 561 DOI 10.17487/RFC2119, March 1997, 562 . 564 [RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S. 565 Rose, "Protocol Modifications for the DNS Security 566 Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005, 567 . 569 [RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms 570 for DNS (EDNS(0))", STD 75, RFC 6891, 571 DOI 10.17487/RFC6891, April 2013, 572 . 574 8.2. Informative References 576 [GeoffValidation] 577 APNIC, G. H., "A quick review of DNSSEC Validation in 578 today's Internet", June 2016, . 581 [RFC2845] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B. 582 Wellington, "Secret Key Transaction Authentication for DNS 583 (TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000, 584 . 586 [RFC8094] Reddy, T., Wing, D., and P. Patil, "DNS over Datagram 587 Transport Layer Security (DTLS)", RFC 8094, 588 DOI 10.17487/RFC8094, February 2017, 589 . 591 Authors' Addresses 593 Warren Kumari 594 Google 595 1600 Amphitheatre Parkway 596 Mountain View, CA 94043 597 US 599 Email: warren@kumari.net 601 Evan Hunt 602 ISC 603 950 Charter St 604 Redwood City, CA 94063 605 US 607 Email: each@isc.org 609 Roy Arends 610 ICANN 612 Email: roy.arends@icann.org 613 Wes Hardaker 614 USC/ISI 615 P.O. Box 382 616 Davis, CA 95617 617 US 619 Email: ietf@hardakers.net 621 David C Lawrence 622 Oracle + Dyn 623 150 Dow St 624 Manchester, NH 03101 625 US 627 Email: tale@dd.org