idnits 2.17.1 draft-ietf-dnsop-dns-catalog-zones-03.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: When a "serial" property is present for a member zone and it matches the SOA serial of that member zone, implementations of catalog zones which are secondary for that member zone MAY ignore the refresh time in the SOA record of the member zone and rely on updates via the "serial" property of the member zone. A refresh timer of a catalog zone MUST not be ignored. -- The document date (25 August 2021) is 972 days in the past. Is this intentional? -- Found something which looks like a code comment -- if you have code sections in the document, please surround them with '' and '' lines. Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) No issues found here. Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 DNSOP Working Group P. van Dijk 3 Internet-Draft PowerDNS 4 Intended status: Standards Track L. Peltan 5 Expires: 26 February 2022 CZ.NIC 6 O. Sury 7 Internet Systems Consortium 8 W. Toorop 9 NLnet Labs 10 L. Vandewoestijne 11 25 August 2021 13 DNS Catalog Zones 14 draft-ietf-dnsop-dns-catalog-zones-03 16 Abstract 18 This document describes a method for automatic DNS zone provisioning 19 among DNS primary and secondary nameservers by storing and 20 transferring the catalog of zones to be provisioned as one or more 21 regular DNS zones. 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at https://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on 26 February 2022. 40 Copyright Notice 42 Copyright (c) 2021 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 47 license-info) in effect on the date of publication of this document. 48 Please review these documents carefully, as they describe your rights 49 and restrictions with respect to this document. Code Components 50 extracted from this document must include Simplified BSD License text 51 as described in Section 4.e of the Trust Legal Provisions and are 52 provided without warranty as described in the Simplified BSD License. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 57 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 58 3. Description . . . . . . . . . . . . . . . . . . . . . . . . . 4 59 4. Catalog Zone Structure . . . . . . . . . . . . . . . . . . . 4 60 4.1. SOA and NS Records . . . . . . . . . . . . . . . . . . . 4 61 4.2. Catalog Zone Schema Version . . . . . . . . . . . . . . . 5 62 4.3. List of Member Zones . . . . . . . . . . . . . . . . . . 5 63 5. Properties . . . . . . . . . . . . . . . . . . . . . . . . . 6 64 5.1. The Change of ownership (Coo) Property . . . . . . . . . 6 65 5.2. The Group Property . . . . . . . . . . . . . . . . . . . 7 66 5.2.1. Group Property Example . . . . . . . . . . . . . . . 7 67 5.3. The Epoch Property . . . . . . . . . . . . . . . . . . . 8 68 5.3.1. The TIMESTAMP Resource Record . . . . . . . . . . . . 8 69 5.4. The Serial Property . . . . . . . . . . . . . . . . . . . 9 70 5.4.1. The SERIAL Resource Record . . . . . . . . . . . . . 10 71 5.4.2. SERIAL RDATA Wire Format . . . . . . . . . . . . . . 10 72 5.4.3. SERIAL Presentation Format . . . . . . . . . . . . . 11 73 5.4.4. SERIAL RR Usage . . . . . . . . . . . . . . . . . . . 11 74 5.5. Custom properties . . . . . . . . . . . . . . . . . . . . 11 75 6. Nameserver Behavior . . . . . . . . . . . . . . . . . . . . . 11 76 6.1. General Requirements . . . . . . . . . . . . . . . . . . 11 77 6.2. Member zone removal . . . . . . . . . . . . . . . . . . . 12 78 6.3. Member zone name clash . . . . . . . . . . . . . . . . . 12 79 6.4. Migrating member zones between catalogs . . . . . . . . . 12 80 6.5. Zone associated state reset . . . . . . . . . . . . . . . 13 81 7. Implementation Notes . . . . . . . . . . . . . . . . . . . . 13 82 8. Implementation Status . . . . . . . . . . . . . . . . . . . . 14 83 9. Security Considerations . . . . . . . . . . . . . . . . . . . 14 84 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 85 10.1. TIMESTAMP RR type . . . . . . . . . . . . . . . . . . . 15 86 10.2. SERIAL RR type . . . . . . . . . . . . . . . . . . . . . 15 87 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 16 88 12. Normative References . . . . . . . . . . . . . . . . . . . . 16 89 13. Informative References . . . . . . . . . . . . . . . . . . . 17 90 Appendix A. Change History (to be removed before final 91 publication) . . . . . . . . . . . . . . . . . . . . . . 17 92 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 94 1. Introduction 96 The content of a DNS zone is synchronized amongst its primary and 97 secondary nameservers using AXFR and IXFR. However, the list of 98 zones served by the primary (called a catalog in [RFC1035]) is not 99 automatically synchronized with the secondaries. To add or remove a 100 zone, the administrator of a DNS nameserver farm not only has to add 101 or remove the zone from the primary, they must also add/remove the 102 zone from all secondaries, either manually or via an external 103 application. This can be both inconvenient and error-prone; it is 104 also dependent on the nameserver implementation. 106 This document describes a method in which the catalog is represented 107 as a regular DNS zone (called a "catalog zone" here), and transferred 108 using DNS zone transfers. As zones are added to or removed from the 109 catalog zone, these changes are distributed to the secondary 110 nameservers in the normal way. The secondary nameservers then 111 add/remove/modify the zones they serve in accordance with the changes 112 to the catalog zone. 114 The contents and representation of catalog zones are described in 115 Section 3. Nameserver behavior is described in Section 6. 117 2. Terminology 119 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 120 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 121 "OPTIONAL" in this document are to be interpreted as described in BCP 122 14 [RFC2119] [RFC8174] when, and only when, they appear in all 123 capitals, as shown here. 125 Catalog zone A DNS zone containing a DNS catalog, that is, a list of 126 DNS zones and associated properties. 128 Member zone A DNS zone whose configuration is published inside a 129 catalog zone. 131 "$CATZ" Used in examples as a placeholder to represent the domain 132 name of the catalog zone itself (c.f. $ORIGIN). 134 Catalog producer An entity that generates and is responsible for the 135 contents of the catalog zone. 137 Catalog consumer An entity that extracts information from the 138 catalog zone (such as a DNS server that configures itself 139 according to the catalog zone's contents). 141 Member node The DNS name of the DNS subtree representing a given 142 member zone (two levels below "$CATZ"). 144 3. Description 146 A catalog zone is a specially crafted DNS zone that contains, as DNS 147 zone content: 149 * A list of DNS zones (called "member zones"), plus properties 150 associated with those zones. 152 Implementations of catalog zones SHOULD ignore any RR in the catalog 153 zone which is meaningless or useless to the implementation. 155 Authoritative servers may be preconfigured with multiple catalog 156 zones, each associated with a different set of configurations. A 157 member zone can as such be reconfigured with a different set of 158 preconfigured settings by removing it as a member of one catalog zone 159 and making it a member of another. 161 Although the contents of a catalog zone are interpreted and acted 162 upon by nameservers, a catalog zone is a regular DNS zone and so must 163 adhere to the standards for such zones. 165 A catalog zone is primarily intended for the management of a farm of 166 authoritative nameservers. It is not expected that the content of 167 catalog zones will be accessible from any recursive nameserver. 169 4. Catalog Zone Structure 171 4.1. SOA and NS Records 173 As with any other DNS zone, a catalog zone MUST have a syntactically 174 correct SOA record and at least one NS record at its apex. 176 The SOA record's SERIAL, REFRESH, RETRY and EXPIRE fields [RFC1035] 177 are used during zone transfer. A catalog zone's SOA SERIAL field 178 MUST increase when an update is made to the catalog zone's contents 179 as per serial number arithmetic defined in [RFC1982]. Otherwise, 180 secondary nameservers might not notice updates to the catalog zone's 181 contents. 183 There is no requirement to be able to query the catalog zone via 184 recursive nameservers. Implementations of catalog zones MUST ignore 185 and MUST NOT assume or require NS records at the apex. However, at 186 least one is still required so that catalog zones are syntactically 187 correct DNS zones. A single NS RR with a NSDNAME field containing 188 the absolute name "invalid." is RECOMMENDED [RFC2606]. 190 4.2. Catalog Zone Schema Version 192 The catalog zone schema version is specified by an integer value 193 embedded in a TXT RR named "version.$CATZ". All catalog zones MUST 194 have a TXT RRset named "version.$CATZ" with at least one RR. Primary 195 and secondary nameservers MUST NOT apply catalog zone processing to 196 zones without the expected value in one of the RRs in the 197 "version.$CATZ" TXT RRset, but they may be transferred as ordinary 198 zones. For this memo, the value of one of the RRs in the 199 "version.CATZ" TXT RRset MUST be set to "2", i.e. 201 version.$CATZ 0 IN TXT "2" 203 NB: Version 1 was used in a draft version of this memo and reflected 204 the implementation first found in BIND 9.11. 206 4.3. List of Member Zones 208 The list of member zones is specified as a collection of member 209 nodes, represented by domain names under the owner name "zones" where 210 "zones" is a direct child domain of the catalog zone. 212 The names of member zones are represented on the RDATA side (instead 213 of as a part of owner names) of a PTR record, so that all valid 214 domain names may be represented regardless of their length [RFC1035]. 215 This PTR record MUST be the only record in the PTR RRset with the 216 same name. 218 For example, if a catalog zone lists three zones "example.com.", 219 "example.net." and "example.org.", the member node RRs would appear 220 as follows: 222 .zones.$CATZ 0 IN PTR example.com. 223 .zones.$CATZ 0 IN PTR example.net. 224 .zones.$CATZ 0 IN PTR example.org. 226 where "" is a label that tags each record in the 227 collection. "" has an unique value in the collection. 229 Member node labels carry no informational meaning beyond labeling 230 member zones. A changed label may indicate that the state for a zone 231 needs to be reset (see Section 6.5). 233 Having the zones uniquely tagged with the "" label ensures 234 that additional RRs can be added below the member node (see 235 Section 5). Further, if member zones do not share a PTR RRset, the 236 list of member zones can be split over multiple DNS messages in a 237 zone transfer. 239 A catalog zone consumer MUST ignore PTR RRsets with more than a 240 single record. 242 The CLASS field of every RR in a catalog zone MUST be IN (1). 244 The TTL field's value is not defined by this memo. Catalog zones are 245 for authoritative nameserver management only and are not intended for 246 general querying via recursive resolvers. 248 5. Properties 250 Each member zone MAY have one or more additional properties, 251 described in this chapter. These properties are completely optional 252 and the catalog zone consumer SHOULD ignore those it does not 253 understand. Properties are represented by RRsets below the 254 corresponding member node. 256 5.1. The Change of ownership (Coo) Property 258 The 'coo' property facilitates controlled migration of a member zone 259 from one catalog to another. 261 A Change Of Ownership is signaled by the 'coo' property in the 262 catalog zone currently `"owning'' the zone. The name of the new 263 catalog is in the value of a PTR record in the old catalog. For 264 example if member "example.com." will migrate from catalog 265 zone""OLDCATZ` to catalog zone `"NEWCATZ", this appears in 266 the"$OLDCATZ` catalog zone as follows: 268 .zones.$OLDCATZ 0 IN PTR example.com. 269 coo..zones.$OLDCATZ 0 IN PTR zones.$NEWCATZ 271 The PTR RRset MUST consist of a single PTR record. A catalog zone 272 consumer MUST ignore PTR RRsets with more than a single record. 274 When a catalog zone consumer of catalog zone "$OLDCATZ" receives an 275 update which adds or changes a "coo" property for a member zone in 276 "$OLDCATZ" signalling a new owner "$NEWCATZ", it does _not_ migrate 277 the member zone immediately. 279 This is because the catalog zone consumer may not have the "" identifier associated with the member zone in "$NEWCATZ" and 281 because name servers do not index Resource Records by RDATA, it may 282 not know wether or not the member zone is configured in "$NEWCATZ" at 283 all. It may have to wait for an update of "$NEWCATZ" adding or 284 changing that member zone. 286 When a catalog zone consumer of catalog zone "$NEWCATZ" receives an 287 update of "$NEWCATZ" which adds or changes a member zone, _and_ that 288 consumer had the member zone associated with "$OLDCATZ", _and_ there 289 is a "coo" property of the member zone in "$OLDCATZ" pointing to 290 "$NEWCATS", _only then_ it will reconfigure the member zone with the 291 for "$NEWCATZ" preconfigured settings. 293 All associated state for the zone (such as the zone data, or DNSSEC 294 keys) is in such case reset, unless the "epoch" property (see 295 Section 5.3) is supported by the catalog zone consumer and the member 296 zone in both "$OLDCATZ" and "$NEWCATZ" have an "epoch" property with 297 the same value. 299 The new owner is advised to increase the serial of the member zone 300 after the ownership change, so that the old owner can detect that the 301 transition is done. The old owner then removes the member zone from 302 "old.catalog". 304 5.2. The Group Property 306 With a "group" property, consumer(s) can be signalled to treat some 307 member zones within the catalog zone differently. 309 The consumer MAY apply different configuration options when 310 processing member zones, based on the value of the "group" property. 311 The exact handling of configuration referred to by the "group" 312 property value is left to the consumer's implementation and 313 configuration. The property is defined by a TXT record in the sub- 314 node labelled "group". 316 The producer MAY assign a "group" property to all, some, or none of 317 the member zones within a catalog zone. The producer MUST NOT assign 318 more than one "group" property to one member zone. 320 The consumer MUST ignore either all or none of the "group" properties 321 in a catalog zone. 323 The value of the TXT record MUST be at most 255 octets long and MUST 324 NOT contain whitespace characters. The consumer MUST interpret the 325 value case-sensitively. 327 5.2.1. Group Property Example 329 .zones.$CATZ 0 IN PTR example.com. 330 group..zones.$CATZ 0 IN TXT sign-with-nsec3 331 .zones.$CATZ 0 IN PTR example.net. 332 group..zones.$CATZ 0 IN TXT nodnssec 333 In this case, the consumer might be implemented and configured in the 334 way that the member zones with "nodnssec" group assigned will not be 335 signed with DNSSEC, and the zones with "sign-with-nsec3" group 336 assigned will be signed with DNSSEC with NSEC3 chain. 338 By generating the catalog zone (snippet) above, the producer signals 339 how the consumer shall treat DNSSEC for the zones example.net. and 340 example.com., respectively. 342 5.3. The Epoch Property 344 A "epoch" property allows a producer to trigger, on the consumer, a 345 reset of all state associated with a zone. 347 The epoch property is represented by a the "TIMESTAMP" Resource 348 Record (see Section 5.3.1). 350 * "epoch..zones.$CATZ 0 IN TIMESTAMP ..." 352 When a member zone's epoch changes, the secondary server resets the 353 member zone's state. The secondary can detect a member zone epoch 354 change as follows: 356 * When the epoch changes, the primary will set the TIMESTAMP RR of 357 the member zone's epoch property to the current time. 359 * When the secondary processes a member node with an epoch property 360 that is larger than the point in time when the member zone itself 361 was last retrieved, then a new epoch has begun. 363 The steps entailed in the process of resetting the zone state depend 364 on the operational context of the secondary (e.g. regenerate DNSSEC 365 keys). 367 5.3.1. The TIMESTAMP Resource Record 369 Epoch values (both for the catalog zone and for member zones) are 370 provided with a TIMESTAMP Resource Record. The Type value for the 371 TIMESTAMP RR is TBD. The TIMESTAMP RR is class independent. The 372 RDATA of the resource record consists of a single field: Timestamp. 374 5.3.1.1. TIMESTAMP RDATA Wire Format 376 The TIMESTAMP RDATA wire format is encoded as follows: 378 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 379 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 380 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 381 | Timestamp | 382 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 384 The wire format is identical to the wire format of the Signature 385 Expiration and Inception Fields of the RRSIG RR ([RFC4034] section 386 3.1.5) and follows the same rules with respect to wrapping. 388 5.3.1.2. TIMESTAMP RDATA Presentation Format 390 The presentation format is identical to that of the Signature 391 Expiration and Inception Fields of the RRSIG RR ([RFC4034] section 392 3.2). Example: 394 epoch.$CATZ 0 IN TIMESTAMP 20210304124652 395 epoch..zones.$CATZ 0 IN TIMESTAMP 20201231235959 397 5.4. The Serial Property 399 The serial property helps in increasing reliability of zone update 400 signaling and may help in reducing NOTIFY and SOA query traffic. 402 The current default mechanism for prompting notifications of zone 403 changes from a primary nameserver to the secondaries via DNS NOTIFY 404 [RFC1996], can be unreliable due to packet loss, or secondary 405 nameservers temporarily not being reachable. In such cases the 406 secondary might pick up the change only after the refresh timer runs 407 out, which might take long time and be out of the control of the 408 primary nameserver operator. Low refresh values in the zones being 409 served can alleviate update delays, but burden both the primary and 410 secondary nameservers with more refresh queries, especially with 411 larger numbers of secondary nameservers serving large numbers of 412 zones. To mitigate this, updates of zones MAY be signalled via 413 catalog zones with the help of a "serial" property. 415 The serial number in the SOA record of the most recent version of a 416 member zone MAY be provided by a "serial" property. When a "serial" 417 property is present for a member zone, implementations of catalog 418 zones MAY assume this number to be the current serial number in the 419 SOA record of the most recent version of the member zone. 421 Nameservers that are secondary for that member zone, MAY compare the 422 "serial" property with the SOA serial since the last time the zone 423 was fetched. When the "serial" property is larger, the secondary MAY 424 initiate a zone transfer immediately without doing a SOA query first. 425 The SOA query may be omitted, because the SOA serial has been 426 obtained reliably via the catalog zone already. 428 When a "serial" property is present for a member zone and it matches 429 the SOA serial of that member zone, implementations of catalog zones 430 which are secondary for that member zone MAY ignore the refresh time 431 in the SOA record of the member zone and rely on updates via the 432 "serial" property of the member zone. A refresh timer of a catalog 433 zone MUST not be ignored. 435 Primary nameservers MAY be configured to omit sending DNS NOTIFY 436 messages to secondary nameservers which are known to process the 437 "serial" property of the member zones in that catalog. However they 438 MAY also combine signalling of zone changes with the "serial" 439 property of a member zone, as well as sending DNS NOTIFY messages, to 440 anticipate slow updates of the catalog zone (due to packet loss or 441 other reasons) and to cater for secondaries that do not process the 442 "serial" property. 444 All comparisons of serial numbers MUST use "Serial number 445 arithmetic", as defined in [RFC1982] 447 5.4.1. The SERIAL Resource Record 449 The "serial" property value is provided with a SERIAL Resource 450 Record. The Type value for the SERIAL RR is TBD. The SERIAL RR is 451 class independent. The RDATA of the resource record consist of a 452 single field: Serial. 454 5.4.2. SERIAL RDATA Wire Format 456 The SERIAL RDATA wire format is encoded as follows: 458 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 459 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 460 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 461 | Serial | 462 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 464 5.4.2.1. The Serial Field 466 The Serial field is a 32-bit unsigned integer in network byte order. 467 It is the serial number of the member zone's SOA record ([RFC1035] 468 section 3.3.13). 470 5.4.3. SERIAL Presentation Format 472 The presentation format of the RDATA portion is as follows: 474 The Serial fields is represented as an unsigned decimal integer. 476 5.4.4. SERIAL RR Usage 478 The "serial" property of a member zone is provided by a SERIAL RRset 479 with a single SERIAL RR named "serial..zones.$CATZ". 481 For example, if a catalog zone lists three zones "example.com.", 482 "example.net." and "example.org.", and a "serial" property is 483 provided for each of them, the RRs would appear as follows: 485 .zones.$CATZ 0 IN PTR example.com. 486 serial..zones.$CATZ 0 IN SERIAL 2020111712 487 .zones.$CATZ 0 IN PTR example.net. 488 serial..zones.$CATZ 0 IN SERIAL 2020111709 489 .zones.$CATZ 0 IN PTR example.org. 490 serial..zones.$CATZ 0 IN SERIAL 2020112405 492 5.5. Custom properties 494 Implementations and operators of catalog zones may choose to provide 495 their own properties below the label "private-extension..zones.$CATZ". "private-extension" is not a placeholder, so a 497 custom property would have the domain name ".private- 498 extension..zones.$CATZ" 500 6. Nameserver Behavior 502 6.1. General Requirements 504 As it is a regular DNS zone, a catalog zone can be transferred using 505 DNS zone transfers among nameservers. 507 Although they are regular DNS zones, catalog zones contain only 508 information for the management of a set of authoritative nameservers. 509 For this reason, operators may want to limit the systems able to 510 query these zones. It may be inconvenient to serve some contents of 511 catalog zones via DNS queries anyway due to the nature of their 512 representation. A separate method of querying entries inside the 513 catalog zone may be made available by nameserver implementations (see 514 Section 7). 516 Catalog updates should be automatic, i.e., when a nameserver that 517 supports catalog zones completes a zone transfer for a catalog zone, 518 it SHOULD apply changes to the catalog within the running nameserver 519 automatically without any manual intervention. 521 As with regular zones, primary and secondary nameservers for a 522 catalog zone may be operated by different administrators. The 523 secondary nameservers may be configured to synchronize catalog zones 524 from the primary, but the primary's administrators may not have any 525 administrative access to the secondaries. 527 A catalog zone can be updated via DNS UPDATE on a reference primary 528 nameserver, or via zone transfers. Nameservers MAY allow loading and 529 transfer of broken zones with incorrect catalog zone syntax (as they 530 are treated as regular zones), but nameservers MUST NOT process such 531 broken zones as catalog zones. For the purpose of catalog 532 processing, the broken catalogs MUST be ignored. 534 6.2. Member zone removal 536 When a member zone is removed from a specific catalog zone, an 537 authoritative server MUST NOT remove the zone and associated state 538 data if the zone was not configured from that specific catalog zone. 539 Only when the zone was configured from a specific catalog zone, and 540 the zone is removed as a member from that specific catalog zone, the 541 zone and associated state (such as zone data and DNSSEC keys) MAY be 542 removed. 544 6.3. Member zone name clash 546 If there is a clash between an existing zone's name (either from an 547 existing member zone or otherwise configured zone) and an incoming 548 member zone's name (via transfer or update), the new instance of the 549 zone MUST be ignored and an error SHOULD be logged. 551 A clash between an existing member zone's name and an incoming member 552 zone's name (via transfer or update), may be an attempt to migrate a 553 zone to a different catalog. 555 6.4. Migrating member zones between catalogs 557 If all consumers of the catalog zones involved support the "coo" 558 property, it is RECOMMENDED to perform migration of a member zone by 559 following the procedure described in Section 5.1. Otherwise a 560 migration of member zone from a catalog zone "$OLDCATZ" to a catalog 561 zone "$NEWCATZ" has to be done by: first removing the member zone 562 from "$OLDCATZ"; second adding the member zone to "$NEWCATZ". 564 If in the process of a migration some consumers of the involved 565 catalog zones did not catch the removal of the member zone from 566 "$OLDCATZ" yet (because of a lost packet or down time or otherwise), 567 but did already see the update of "$NEWCATZ", they may consider the 568 update adding the member zone in "$NEWCATZ" to be a name clash (see 569 #nameclash) and as a consequence the member is not migrated to 570 "$NEWCATZ". This possibility needs to be anticipated with a member 571 zone migration. Recovery from such a situation is out of the scope 572 of this document. It may for example entail a manually forced 573 retransfer of "$NEWCATZ" to consumers after they have been detected 574 to have received and processed the removal of the member zone from 575 "$OLDCATZ". 577 6.5. Zone associated state reset 579 It may be desirable to reset state (such as zone data and DNSSEC 580 keys) associated with a member zone. If all consumers of the catalog 581 zone support the "epoch" property, it is RECOMMENDED to perform a 582 zone state reset following the procedure described in Section 5.3. 583 Otherwise a zone state reset has to be done by: first removing the 584 member zone from the catalog; add the member zone to the catalog 585 again after having made sure all catalog zone consumers did process 586 the member zone removal. 588 If in the process of a zone state reset some consumers of the 589 involved catalog zone did not catch the removal (because of a lost 590 packet or down time or otherwise) they will not have the zone 591 associated state reset. This possibility needs to be anticipated. 592 Recovery from it is out of the scope of this document. It may for 593 example entail manual removal of the zone associated state from the 594 catalog zone consumers that did not catch the removal and re-addition 595 of the member. 597 7. Implementation Notes 599 Catalog zones on secondary nameservers would have to be setup 600 manually, perhaps as static configuration, similar to how ordinary 601 DNS zones are configured. Members of such catalog zones will be 602 automatically synchronized by the secondary after the catalog zone is 603 configured. 605 An administrator may want to look at data inside a catalog zone. 606 Typical queries might include dumping the list of member zones, 607 dumping a member zone's effective configuration, querying a specific 608 property value of a member zone, etc. Because of the structure of 609 catalog zones, it may not be possible to perform these queries 610 intuitively, or in some cases, at all, using DNS QUERY. For example, 611 it is not possible to enumerate the contents of a multi-valued 612 property (such as the list of member zones) with a single QUERY. 613 Implementations are therefore advised to provide a tool that uses 614 either the output of AXFR or an out-of-band method to perform queries 615 on catalog zones. 617 8. Implementation Status 619 *Note to the RFC Editor*: please remove this entire section before 620 publication. 622 In the following implementation status descriptions, "DNS Catalog 623 Zones" refers to DNS Catalog Zones as described in this document. 625 * Knot DNS has processing of DNS Catalog Zones since Knot DNS 626 Version 3.0.0, which was released on September 9, 2020. 628 * Knot DNS has generation of DNS Catalog Zones on a development 629 branch (https://gitlab.nic.cz/knot/knot-dns/-/tree/ 630 catalog_generate). 632 * PowerDNS has a proof of concept external program called PowerCATZ 633 (https://github.com/PowerDNS/powercatz/), that can process DNS 634 Catalog Zones. 636 * Proof of concept python scripts (https://github.com/IETF- 637 Hackathon/NSDCatZ) that can be used for both generating and 638 consuming DNS Catalog Zones with NSD have been developed during 639 the hackathon at the IETF-109. 641 Interoperability between the above implementations has been tested 642 during the hackathon at the IETF-109. 644 9. Security Considerations 646 As catalog zones are transmitted using DNS zone transfers, it is key 647 for these transfers to be protected from unexpected modifications on 648 the route. So, catalog zone transfers SHOULD be authenticated using 649 TSIG [RFC8945]. A primary nameserver SHOULD NOT serve a catalog zone 650 for transfer without using TSIG and a secondary nameserver SHOULD 651 abandon an update to a catalog zone that was received without using 652 TSIG. 654 Use of DNS UPDATE [RFC2136] to modify the content of catalog zones 655 SHOULD similarly be authenticated using TSIG. 657 Zone transfers of member zones SHOULD similarly be authenticated 658 using TSIG [RFC8945]. The TSIG shared secrets used for member zones 659 MUST NOT be mentioned anywhere in the catalog zone data. However, 660 key identifiers may be shared within catalog zones. 662 Catalog zones reveal the zones served by the consumers of the catalog 663 zone. It is RECOMMENDED to limit the systems able to query these 664 zones. It is RECOMMENDED to transfer catalog zones confidentially 665 [RFC9103]. 667 Administrative control over what zones are served from the configured 668 name servers shifts completely from the server operator (consumer) to 669 the "owner" (producer) of the catalog zone content. 671 10. IANA Considerations 673 10.1. TIMESTAMP RR type 675 This document defines a new DNS RR type, TIMESTAMP, in the "Resource 676 Record (RR) TYPEs" subregistry of the "Domain Name System (DNS) 677 Parameters" registry: 679 +===========+=======+===========+=================+ 680 | TYPE | Value | Meaning | Reference | 681 +===========+=======+===========+=================+ 682 | TIMESTAMP | TBD | Timestamp | [this document] | 683 +-----------+-------+-----------+-----------------+ 685 Table 1 687 10.2. SERIAL RR type 689 This document defines a new DNS RR type, SERIAL, in the "Resource 690 Record (RR) TYPEs" subregistry of the "Domain Name System (DNS) 691 Parameters" registry: 693 +========+=======+===========================+===========+ 694 | TYPE | Value | Meaning | Reference | 695 +========+=======+===========================+===========+ 696 | SERIAL | TBD | Version number of the | [this | 697 | | | original copy of the zone | document] | 698 +--------+-------+---------------------------+-----------+ 700 Table 2 702 11. Acknowledgements 704 Our deepest thanks and appreciation go to Stephen Morris, Ray Bellis 705 and Witold Krecicki who initiated this draft and did the bulk of the 706 work. 708 Catalog zones originated as the chosen method among various proposals 709 that were evaluated at ISC for easy zone management. The chosen 710 method of storing the catalog as a regular DNS zone was proposed by 711 Stephen Morris. 713 The initial authors discovered that Paul Vixie's earlier [Metazones] 714 proposal implemented a similar approach and reviewed it. Catalog 715 zones borrows some syntax ideas from Metazones, as both share this 716 scheme of representing the catalog as a regular DNS zone. 718 Thanks to Brian Conry, Tony Finch, Evan Hunt, Patrik Lundin, Victoria 719 Risk, Carsten Strotmann, Peter Thomassen and Kees Monshouwer for 720 reviewing draft proposals and offering comments and suggestions. 722 Thanks to Klaus Darilion who came up with the idea for the "serial" 723 property during the hackathon at the IETF-109. Thanks also to Shane 724 Kerr, Petr Spacek, Brian Dickson for further brainstorming and 725 discussing the "serial" property and how it would work best with 726 catalog zones. 728 12. Normative References 730 [RFC1035] Mockapetris, P., "Domain names - implementation and 731 specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, 732 November 1987, . 734 [RFC1982] Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982, 735 DOI 10.17487/RFC1982, August 1996, 736 . 738 [RFC1996] Vixie, P., "A Mechanism for Prompt Notification of Zone 739 Changes (DNS NOTIFY)", RFC 1996, DOI 10.17487/RFC1996, 740 August 1996, . 742 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 743 Requirement Levels", BCP 14, RFC 2119, 744 DOI 10.17487/RFC2119, March 1997, 745 . 747 [RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound, 748 "Dynamic Updates in the Domain Name System (DNS UPDATE)", 749 RFC 2136, DOI 10.17487/RFC2136, April 1997, 750 . 752 [RFC2606] Eastlake 3rd, D. and A. Panitz, "Reserved Top Level DNS 753 Names", BCP 32, RFC 2606, DOI 10.17487/RFC2606, June 1999, 754 . 756 [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. 757 Rose, "Resource Records for the DNS Security Extensions", 758 RFC 4034, DOI 10.17487/RFC4034, March 2005, 759 . 761 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 762 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 763 May 2017, . 765 [RFC8945] Dupont, F., Morris, S., Vixie, P., Eastlake 3rd, D., 766 Gudmundsson, O., and B. Wellington, "Secret Key 767 Transaction Authentication for DNS (TSIG)", STD 93, 768 RFC 8945, DOI 10.17487/RFC8945, November 2020, 769 . 771 [RFC9103] Toorop, W., Dickinson, S., Sahib, S., Aras, P., and A. 772 Mankin, "DNS Zone Transfer over TLS", RFC 9103, 773 DOI 10.17487/RFC9103, August 2021, 774 . 776 13. Informative References 778 [Metazones] 779 Vixie, P., "Federated Domain Name Service Using DNS 780 Metazones", 2005, . 782 Appendix A. Change History (to be removed before final publication) 784 * draft-muks-dnsop-dns-catalog-zones-00 786 | Initial public draft. 788 * draft-muks-dnsop-dns-catalog-zones-01 790 | Added Witold, Ray as authors. Fixed typos, consistency issues. 791 | Fixed references. Updated Area. Removed newly introduced custom 792 | RR TYPEs. Changed schema version to 1. Changed TSIG requirement 793 | from MUST to SHOULD. Removed restrictive language about use of 794 | DNS QUERY. When zones are introduced into a catalog zone, a 795 | primary SHOULD first make the new zones available for transfers 796 | first (instead of MUST). Updated examples, esp. use IPv6 in 797 | examples per Fred Baker. Add catalog zone example. 799 * draft-muks-dnsop-dns-catalog-zones-02 801 | Addressed some review comments by Patrik Lundin. 803 * draft-muks-dnsop-dns-catalog-zones-03 805 | Revision bump. 807 * draft-muks-dnsop-dns-catalog-zones-04 809 | Reordering of sections into more logical order. Separation of 810 | multi-valued properties into their own category. 812 * draft-toorop-dnsop-dns-catalog-zones-00 814 | New authors to pickup the editor pen on this draft 815 | 816 | Remove data type definitions for zone properties Removing 817 | configuration of member zones through zone properties altogether 818 | 819 | Remove Open issues and discussion Appendix, which was about zone 820 | options (including primary/secondary relationships) only. 822 * draft-toorop-dnsop-dns-catalog-zones-01 824 | Added a new section "The Serial Property", introducing a new 825 | mechanism which can help with disseminating zones from the primary 826 | to the secondary nameservers in a timely fashion more reliably. 827 | 828 | Three different ways to provide a "serial" property with a member 829 | zone are offered to or the workgroup for discussion. 830 | 831 | Added a new section "Implementation Status", listing production 832 | ready, upcoming and Proof of Concept implementations, and 833 | reporting on interoperability of the different implementations. 835 * draft-toorop-dnsop-dns-catalog-zones-02 837 | Adding the "coo" property for zone migration in a controlled 838 | fashion 839 | 840 | Adding the "group" property for reconfigure settings of member 841 | zones in an atomic update 842 | 843 | Adding the "epoch" property to reset zone associated state in a 844 | controlled fashion 846 * draft-toorop-dnsop-dns-catalog-zones-03 848 | Big cleanup! 849 | 850 | Introducing the terms catalog zone consumer and catalog zone 851 | producer 852 | 853 | Reorganized topics to create a more coherent whole 854 | 855 | Properties all have consistent format now 856 | 857 | Try to assume the least possible from implementations w.r.t.: 858 | 859 | 1) Predictability of the IDs of member zones 860 | 861 | 2) Whether or not fallback catalog zones can be found for a member 862 | 863 | 3) Whether or not a catalog zone consumer can maintain state 865 Authors' Addresses 867 Peter van Dijk 868 PowerDNS 869 Den Haag 870 Netherlands 872 Email: peter.van.dijk@powerdns.com 874 Libor Peltan 875 CZ.NIC 876 Czechia 878 Email: libor.peltan@nic.cz 880 Ondrej Sury 881 Internet Systems Consortium 882 Czechia 884 Email: ondrej@isc.org 885 Willem Toorop 886 NLnet Labs 887 Science Park 400 888 1098 XH Amsterdam 889 Netherlands 891 Email: willem@nlnetlabs.nl 893 Leo Vandewoestijne 894 Netherlands 896 Email: leo@dns.company