DNS Catalog Zones
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This is an older version of an Internet-Draft whose latest revision state is "Active".
|Authors||Peter van Dijk , Libor Peltan , Ondřej Surý , Willem Toorop , Leo Vandewoestijne|
|Last updated||2021-08-25 (Latest revision 2021-02-22)|
|RFC stream||Internet Engineering Task Force (IETF)|
GENART Last Call review (of -08) by Russ Housley Almost Ready
DNSDIR Last Call review (of -08) by David Blacka Ready with Nits
OPSDIR Last Call Review Incomplete, due 2022-12-13
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DNSOP Working Group P. van Dijk Internet-Draft PowerDNS Intended status: Standards Track L. Peltan Expires: 26 February 2022 CZ.NIC O. Sury Internet Systems Consortium W. Toorop NLnet Labs L. Vandewoestijne 25 August 2021 DNS Catalog Zones draft-ietf-dnsop-dns-catalog-zones-03 Abstract This document describes a method for automatic DNS zone provisioning among DNS primary and secondary nameservers by storing and transferring the catalog of zones to be provisioned as one or more regular DNS zones. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 26 February 2022. Copyright Notice Copyright (c) 2021 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights van Dijk, et al. Expires 26 February 2022 [Page 1] Internet-Draft dns-catalog-zones August 2021 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 . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Description . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Catalog Zone Structure . . . . . . . . . . . . . . . . . . . 4 4.1. SOA and NS Records . . . . . . . . . . . . . . . . . . . 4 4.2. Catalog Zone Schema Version . . . . . . . . . . . . . . . 5 4.3. List of Member Zones . . . . . . . . . . . . . . . . . . 5 5. Properties . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.1. The Change of ownership (Coo) Property . . . . . . . . . 6 5.2. The Group Property . . . . . . . . . . . . . . . . . . . 7 5.2.1. Group Property Example . . . . . . . . . . . . . . . 7 5.3. The Epoch Property . . . . . . . . . . . . . . . . . . . 8 5.3.1. The TIMESTAMP Resource Record . . . . . . . . . . . . 8 5.4. The Serial Property . . . . . . . . . . . . . . . . . . . 9 5.4.1. The SERIAL Resource Record . . . . . . . . . . . . . 10 5.4.2. SERIAL RDATA Wire Format . . . . . . . . . . . . . . 10 5.4.3. SERIAL Presentation Format . . . . . . . . . . . . . 11 5.4.4. SERIAL RR Usage . . . . . . . . . . . . . . . . . . . 11 5.5. Custom properties . . . . . . . . . . . . . . . . . . . . 11 6. Nameserver Behavior . . . . . . . . . . . . . . . . . . . . . 11 6.1. General Requirements . . . . . . . . . . . . . . . . . . 11 6.2. Member zone removal . . . . . . . . . . . . . . . . . . . 12 6.3. Member zone name clash . . . . . . . . . . . . . . . . . 12 6.4. Migrating member zones between catalogs . . . . . . . . . 12 6.5. Zone associated state reset . . . . . . . . . . . . . . . 13 7. Implementation Notes . . . . . . . . . . . . . . . . . . . . 13 8. Implementation Status . . . . . . . . . . . . . . . . . . . . 14 9. Security Considerations . . . . . . . . . . . . . . . . . . . 14 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 10.1. TIMESTAMP RR type . . . . . . . . . . . . . . . . . . . 15 10.2. SERIAL RR type . . . . . . . . . . . . . . . . . . . . . 15 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 16 12. Normative References . . . . . . . . . . . . . . . . . . . . 16 13. Informative References . . . . . . . . . . . . . . . . . . . 17 Appendix A. Change History (to be removed before final publication) . . . . . . . . . . . . . . . . . . . . . . 17 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 van Dijk, et al. Expires 26 February 2022 [Page 2] Internet-Draft dns-catalog-zones August 2021 1. Introduction The content of a DNS zone is synchronized amongst its primary and secondary nameservers using AXFR and IXFR. However, the list of zones served by the primary (called a catalog in [RFC1035]) is not automatically synchronized with the secondaries. To add or remove a zone, the administrator of a DNS nameserver farm not only has to add or remove the zone from the primary, they must also add/remove the zone from all secondaries, either manually or via an external application. This can be both inconvenient and error-prone; it is also dependent on the nameserver implementation. This document describes a method in which the catalog is represented as a regular DNS zone (called a "catalog zone" here), and transferred using DNS zone transfers. As zones are added to or removed from the catalog zone, these changes are distributed to the secondary nameservers in the normal way. The secondary nameservers then add/remove/modify the zones they serve in accordance with the changes to the catalog zone. The contents and representation of catalog zones are described in Section 3. Nameserver behavior is described in Section 6. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. Catalog zone A DNS zone containing a DNS catalog, that is, a list of DNS zones and associated properties. Member zone A DNS zone whose configuration is published inside a catalog zone. "$CATZ" Used in examples as a placeholder to represent the domain name of the catalog zone itself (c.f. $ORIGIN). Catalog producer An entity that generates and is responsible for the contents of the catalog zone. Catalog consumer An entity that extracts information from the catalog zone (such as a DNS server that configures itself according to the catalog zone's contents). Member node The DNS name of the DNS subtree representing a given van Dijk, et al. Expires 26 February 2022 [Page 3] Internet-Draft dns-catalog-zones August 2021 member zone (two levels below "$CATZ"). 3. Description A catalog zone is a specially crafted DNS zone that contains, as DNS zone content: * A list of DNS zones (called "member zones"), plus properties associated with those zones. Implementations of catalog zones SHOULD ignore any RR in the catalog zone which is meaningless or useless to the implementation. Authoritative servers may be preconfigured with multiple catalog zones, each associated with a different set of configurations. A member zone can as such be reconfigured with a different set of preconfigured settings by removing it as a member of one catalog zone and making it a member of another. Although the contents of a catalog zone are interpreted and acted upon by nameservers, a catalog zone is a regular DNS zone and so must adhere to the standards for such zones. A catalog zone is primarily intended for the management of a farm of authoritative nameservers. It is not expected that the content of catalog zones will be accessible from any recursive nameserver. 4. Catalog Zone Structure 4.1. SOA and NS Records As with any other DNS zone, a catalog zone MUST have a syntactically correct SOA record and at least one NS record at its apex. The SOA record's SERIAL, REFRESH, RETRY and EXPIRE fields [RFC1035] are used during zone transfer. A catalog zone's SOA SERIAL field MUST increase when an update is made to the catalog zone's contents as per serial number arithmetic defined in [RFC1982]. Otherwise, secondary nameservers might not notice updates to the catalog zone's contents. There is no requirement to be able to query the catalog zone via recursive nameservers. Implementations of catalog zones MUST ignore and MUST NOT assume or require NS records at the apex. However, at least one is still required so that catalog zones are syntactically correct DNS zones. A single NS RR with a NSDNAME field containing the absolute name "invalid." is RECOMMENDED [RFC2606]. van Dijk, et al. Expires 26 February 2022 [Page 4] Internet-Draft dns-catalog-zones August 2021 4.2. Catalog Zone Schema Version The catalog zone schema version is specified by an integer value embedded in a TXT RR named "version.$CATZ". All catalog zones MUST have a TXT RRset named "version.$CATZ" with at least one RR. Primary and secondary nameservers MUST NOT apply catalog zone processing to zones without the expected value in one of the RRs in the "version.$CATZ" TXT RRset, but they may be transferred as ordinary zones. For this memo, the value of one of the RRs in the "version.CATZ" TXT RRset MUST be set to "2", i.e. version.$CATZ 0 IN TXT "2" NB: Version 1 was used in a draft version of this memo and reflected the implementation first found in BIND 9.11. 4.3. List of Member Zones The list of member zones is specified as a collection of member nodes, represented by domain names under the owner name "zones" where "zones" is a direct child domain of the catalog zone. The names of member zones are represented on the RDATA side (instead of as a part of owner names) of a PTR record, so that all valid domain names may be represented regardless of their length [RFC1035]. This PTR record MUST be the only record in the PTR RRset with the same name. For example, if a catalog zone lists three zones "example.com.", "example.net." and "example.org.", the member node RRs would appear as follows: <unique-1>.zones.$CATZ 0 IN PTR example.com. <unique-2>.zones.$CATZ 0 IN PTR example.net. <unique-3>.zones.$CATZ 0 IN PTR example.org. where "<unique-N>" is a label that tags each record in the collection. "<unique-N>" has an unique value in the collection. Member node labels carry no informational meaning beyond labeling member zones. A changed label may indicate that the state for a zone needs to be reset (see Section 6.5). Having the zones uniquely tagged with the "<unique-N>" label ensures that additional RRs can be added below the member node (see Section 5). Further, if member zones do not share a PTR RRset, the list of member zones can be split over multiple DNS messages in a zone transfer. van Dijk, et al. Expires 26 February 2022 [Page 5] Internet-Draft dns-catalog-zones August 2021 A catalog zone consumer MUST ignore PTR RRsets with more than a single record. The CLASS field of every RR in a catalog zone MUST be IN (1). The TTL field's value is not defined by this memo. Catalog zones are for authoritative nameserver management only and are not intended for general querying via recursive resolvers. 5. Properties Each member zone MAY have one or more additional properties, described in this chapter. These properties are completely optional and the catalog zone consumer SHOULD ignore those it does not understand. Properties are represented by RRsets below the corresponding member node. 5.1. The Change of ownership (Coo) Property The 'coo' property facilitates controlled migration of a member zone from one catalog to another. A Change Of Ownership is signaled by the 'coo' property in the catalog zone currently `"owning'' the zone. The name of the new catalog is in the value of a PTR record in the old catalog. For example if member "example.com." will migrate from catalog zone""OLDCATZ` to catalog zone `"NEWCATZ", this appears in the"$OLDCATZ` catalog zone as follows: <unique-N>.zones.$OLDCATZ 0 IN PTR example.com. coo.<unique-N>.zones.$OLDCATZ 0 IN PTR zones.$NEWCATZ The PTR RRset MUST consist of a single PTR record. A catalog zone consumer MUST ignore PTR RRsets with more than a single record. When a catalog zone consumer of catalog zone "$OLDCATZ" receives an update which adds or changes a "coo" property for a member zone in "$OLDCATZ" signalling a new owner "$NEWCATZ", it does _not_ migrate the member zone immediately. This is because the catalog zone consumer may not have the "<unique- N>" identifier associated with the member zone in "$NEWCATZ" and because name servers do not index Resource Records by RDATA, it may not know wether or not the member zone is configured in "$NEWCATZ" at all. It may have to wait for an update of "$NEWCATZ" adding or changing that member zone. van Dijk, et al. Expires 26 February 2022 [Page 6] Internet-Draft dns-catalog-zones August 2021 When a catalog zone consumer of catalog zone "$NEWCATZ" receives an update of "$NEWCATZ" which adds or changes a member zone, _and_ that consumer had the member zone associated with "$OLDCATZ", _and_ there is a "coo" property of the member zone in "$OLDCATZ" pointing to "$NEWCATS", _only then_ it will reconfigure the member zone with the for "$NEWCATZ" preconfigured settings. All associated state for the zone (such as the zone data, or DNSSEC keys) is in such case reset, unless the "epoch" property (see Section 5.3) is supported by the catalog zone consumer and the member zone in both "$OLDCATZ" and "$NEWCATZ" have an "epoch" property with the same value. The new owner is advised to increase the serial of the member zone after the ownership change, so that the old owner can detect that the transition is done. The old owner then removes the member zone from "old.catalog". 5.2. The Group Property With a "group" property, consumer(s) can be signalled to treat some member zones within the catalog zone differently. The consumer MAY apply different configuration options when processing member zones, based on the value of the "group" property. The exact handling of configuration referred to by the "group" property value is left to the consumer's implementation and configuration. The property is defined by a TXT record in the sub- node labelled "group". The producer MAY assign a "group" property to all, some, or none of the member zones within a catalog zone. The producer MUST NOT assign more than one "group" property to one member zone. The consumer MUST ignore either all or none of the "group" properties in a catalog zone. The value of the TXT record MUST be at most 255 octets long and MUST NOT contain whitespace characters. The consumer MUST interpret the value case-sensitively. 5.2.1. Group Property Example <unique-1>.zones.$CATZ 0 IN PTR example.com. group.<unique-1>.zones.$CATZ 0 IN TXT sign-with-nsec3 <unique-2>.zones.$CATZ 0 IN PTR example.net. group.<unique-2>.zones.$CATZ 0 IN TXT nodnssec van Dijk, et al. Expires 26 February 2022 [Page 7] Internet-Draft dns-catalog-zones August 2021 In this case, the consumer might be implemented and configured in the way that the member zones with "nodnssec" group assigned will not be signed with DNSSEC, and the zones with "sign-with-nsec3" group assigned will be signed with DNSSEC with NSEC3 chain. By generating the catalog zone (snippet) above, the producer signals how the consumer shall treat DNSSEC for the zones example.net. and example.com., respectively. 5.3. The Epoch Property A "epoch" property allows a producer to trigger, on the consumer, a reset of all state associated with a zone. The epoch property is represented by a the "TIMESTAMP" Resource Record (see Section 5.3.1). * "epoch.<unique-N>.zones.$CATZ 0 IN TIMESTAMP ..." When a member zone's epoch changes, the secondary server resets the member zone's state. The secondary can detect a member zone epoch change as follows: * When the epoch changes, the primary will set the TIMESTAMP RR of the member zone's epoch property to the current time. * When the secondary processes a member node with an epoch property that is larger than the point in time when the member zone itself was last retrieved, then a new epoch has begun. The steps entailed in the process of resetting the zone state depend on the operational context of the secondary (e.g. regenerate DNSSEC keys). 5.3.1. The TIMESTAMP Resource Record Epoch values (both for the catalog zone and for member zones) are provided with a TIMESTAMP Resource Record. The Type value for the TIMESTAMP RR is TBD. The TIMESTAMP RR is class independent. The RDATA of the resource record consists of a single field: Timestamp. 22.214.171.124. TIMESTAMP RDATA Wire Format The TIMESTAMP RDATA wire format is encoded as follows: van Dijk, et al. Expires 26 February 2022 [Page 8] Internet-Draft dns-catalog-zones August 2021 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Timestamp | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The wire format is identical to the wire format of the Signature Expiration and Inception Fields of the RRSIG RR ([RFC4034] section 3.1.5) and follows the same rules with respect to wrapping. 126.96.36.199. TIMESTAMP RDATA Presentation Format The presentation format is identical to that of the Signature Expiration and Inception Fields of the RRSIG RR ([RFC4034] section 3.2). Example: epoch.$CATZ 0 IN TIMESTAMP 20210304124652 epoch.<unique-1>.zones.$CATZ 0 IN TIMESTAMP 20201231235959 5.4. The Serial Property The serial property helps in increasing reliability of zone update signaling and may help in reducing NOTIFY and SOA query traffic. The current default mechanism for prompting notifications of zone changes from a primary nameserver to the secondaries via DNS NOTIFY [RFC1996], can be unreliable due to packet loss, or secondary nameservers temporarily not being reachable. In such cases the secondary might pick up the change only after the refresh timer runs out, which might take long time and be out of the control of the primary nameserver operator. Low refresh values in the zones being served can alleviate update delays, but burden both the primary and secondary nameservers with more refresh queries, especially with larger numbers of secondary nameservers serving large numbers of zones. To mitigate this, updates of zones MAY be signalled via catalog zones with the help of a "serial" property. The serial number in the SOA record of the most recent version of a member zone MAY be provided by a "serial" property. When a "serial" property is present for a member zone, implementations of catalog zones MAY assume this number to be the current serial number in the SOA record of the most recent version of the member zone. van Dijk, et al. Expires 26 February 2022 [Page 9] Internet-Draft dns-catalog-zones August 2021 Nameservers that are secondary for that member zone, MAY compare the "serial" property with the SOA serial since the last time the zone was fetched. When the "serial" property is larger, the secondary MAY initiate a zone transfer immediately without doing a SOA query first. The SOA query may be omitted, because the SOA serial has been obtained reliably via the catalog zone already. 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. Primary nameservers MAY be configured to omit sending DNS NOTIFY messages to secondary nameservers which are known to process the "serial" property of the member zones in that catalog. However they MAY also combine signalling of zone changes with the "serial" property of a member zone, as well as sending DNS NOTIFY messages, to anticipate slow updates of the catalog zone (due to packet loss or other reasons) and to cater for secondaries that do not process the "serial" property. All comparisons of serial numbers MUST use "Serial number arithmetic", as defined in [RFC1982] 5.4.1. The SERIAL Resource Record The "serial" property value is provided with a SERIAL Resource Record. The Type value for the SERIAL RR is TBD. The SERIAL RR is class independent. The RDATA of the resource record consist of a single field: Serial. 5.4.2. SERIAL RDATA Wire Format The SERIAL RDATA wire format is encoded as follows: 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Serial | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 188.8.131.52. The Serial Field The Serial field is a 32-bit unsigned integer in network byte order. It is the serial number of the member zone's SOA record ([RFC1035] section 3.3.13). van Dijk, et al. Expires 26 February 2022 [Page 10] Internet-Draft dns-catalog-zones August 2021 5.4.3. SERIAL Presentation Format The presentation format of the RDATA portion is as follows: The Serial fields is represented as an unsigned decimal integer. 5.4.4. SERIAL RR Usage The "serial" property of a member zone is provided by a SERIAL RRset with a single SERIAL RR named "serial.<unique-N>.zones.$CATZ". For example, if a catalog zone lists three zones "example.com.", "example.net." and "example.org.", and a "serial" property is provided for each of them, the RRs would appear as follows: <unique-1>.zones.$CATZ 0 IN PTR example.com. serial.<unique-1>.zones.$CATZ 0 IN SERIAL 2020111712 <unique-2>.zones.$CATZ 0 IN PTR example.net. serial.<unique-2>.zones.$CATZ 0 IN SERIAL 2020111709 <unique-3>.zones.$CATZ 0 IN PTR example.org. serial.<unique-3>.zones.$CATZ 0 IN SERIAL 2020112405 5.5. Custom properties Implementations and operators of catalog zones may choose to provide their own properties below the label "private-extension.<unique- N>.zones.$CATZ". "private-extension" is not a placeholder, so a custom property would have the domain name "<your-label>.private- extension.<unique-N>.zones.$CATZ" 6. Nameserver Behavior 6.1. General Requirements As it is a regular DNS zone, a catalog zone can be transferred using DNS zone transfers among nameservers. Although they are regular DNS zones, catalog zones contain only information for the management of a set of authoritative nameservers. For this reason, operators may want to limit the systems able to query these zones. It may be inconvenient to serve some contents of catalog zones via DNS queries anyway due to the nature of their representation. A separate method of querying entries inside the catalog zone may be made available by nameserver implementations (see Section 7). van Dijk, et al. Expires 26 February 2022 [Page 11] Internet-Draft dns-catalog-zones August 2021 Catalog updates should be automatic, i.e., when a nameserver that supports catalog zones completes a zone transfer for a catalog zone, it SHOULD apply changes to the catalog within the running nameserver automatically without any manual intervention. As with regular zones, primary and secondary nameservers for a catalog zone may be operated by different administrators. The secondary nameservers may be configured to synchronize catalog zones from the primary, but the primary's administrators may not have any administrative access to the secondaries. A catalog zone can be updated via DNS UPDATE on a reference primary nameserver, or via zone transfers. Nameservers MAY allow loading and transfer of broken zones with incorrect catalog zone syntax (as they are treated as regular zones), but nameservers MUST NOT process such broken zones as catalog zones. For the purpose of catalog processing, the broken catalogs MUST be ignored. 6.2. Member zone removal When a member zone is removed from a specific catalog zone, an authoritative server MUST NOT remove the zone and associated state data if the zone was not configured from that specific catalog zone. Only when the zone was configured from a specific catalog zone, and the zone is removed as a member from that specific catalog zone, the zone and associated state (such as zone data and DNSSEC keys) MAY be removed. 6.3. Member zone name clash If there is a clash between an existing zone's name (either from an existing member zone or otherwise configured zone) and an incoming member zone's name (via transfer or update), the new instance of the zone MUST be ignored and an error SHOULD be logged. A clash between an existing member zone's name and an incoming member zone's name (via transfer or update), may be an attempt to migrate a zone to a different catalog. 6.4. Migrating member zones between catalogs If all consumers of the catalog zones involved support the "coo" property, it is RECOMMENDED to perform migration of a member zone by following the procedure described in Section 5.1. Otherwise a migration of member zone from a catalog zone "$OLDCATZ" to a catalog zone "$NEWCATZ" has to be done by: first removing the member zone from "$OLDCATZ"; second adding the member zone to "$NEWCATZ". van Dijk, et al. Expires 26 February 2022 [Page 12] Internet-Draft dns-catalog-zones August 2021 If in the process of a migration some consumers of the involved catalog zones did not catch the removal of the member zone from "$OLDCATZ" yet (because of a lost packet or down time or otherwise), but did already see the update of "$NEWCATZ", they may consider the update adding the member zone in "$NEWCATZ" to be a name clash (see #nameclash) and as a consequence the member is not migrated to "$NEWCATZ". This possibility needs to be anticipated with a member zone migration. Recovery from such a situation is out of the scope of this document. It may for example entail a manually forced retransfer of "$NEWCATZ" to consumers after they have been detected to have received and processed the removal of the member zone from "$OLDCATZ". 6.5. Zone associated state reset It may be desirable to reset state (such as zone data and DNSSEC keys) associated with a member zone. If all consumers of the catalog zone support the "epoch" property, it is RECOMMENDED to perform a zone state reset following the procedure described in Section 5.3. Otherwise a zone state reset has to be done by: first removing the member zone from the catalog; add the member zone to the catalog again after having made sure all catalog zone consumers did process the member zone removal. If in the process of a zone state reset some consumers of the involved catalog zone did not catch the removal (because of a lost packet or down time or otherwise) they will not have the zone associated state reset. This possibility needs to be anticipated. Recovery from it is out of the scope of this document. It may for example entail manual removal of the zone associated state from the catalog zone consumers that did not catch the removal and re-addition of the member. 7. Implementation Notes Catalog zones on secondary nameservers would have to be setup manually, perhaps as static configuration, similar to how ordinary DNS zones are configured. Members of such catalog zones will be automatically synchronized by the secondary after the catalog zone is configured. An administrator may want to look at data inside a catalog zone. Typical queries might include dumping the list of member zones, dumping a member zone's effective configuration, querying a specific property value of a member zone, etc. Because of the structure of catalog zones, it may not be possible to perform these queries intuitively, or in some cases, at all, using DNS QUERY. For example, it is not possible to enumerate the contents of a multi-valued van Dijk, et al. Expires 26 February 2022 [Page 13] Internet-Draft dns-catalog-zones August 2021 property (such as the list of member zones) with a single QUERY. Implementations are therefore advised to provide a tool that uses either the output of AXFR or an out-of-band method to perform queries on catalog zones. 8. Implementation Status *Note to the RFC Editor*: please remove this entire section before publication. In the following implementation status descriptions, "DNS Catalog Zones" refers to DNS Catalog Zones as described in this document. * Knot DNS has processing of DNS Catalog Zones since Knot DNS Version 3.0.0, which was released on September 9, 2020. * Knot DNS has generation of DNS Catalog Zones on a development branch (https://gitlab.nic.cz/knot/knot-dns/-/tree/ catalog_generate). * PowerDNS has a proof of concept external program called PowerCATZ (https://github.com/PowerDNS/powercatz/), that can process DNS Catalog Zones. * Proof of concept python scripts (https://github.com/IETF- Hackathon/NSDCatZ) that can be used for both generating and consuming DNS Catalog Zones with NSD have been developed during the hackathon at the IETF-109. Interoperability between the above implementations has been tested during the hackathon at the IETF-109. 9. Security Considerations As catalog zones are transmitted using DNS zone transfers, it is key for these transfers to be protected from unexpected modifications on the route. So, catalog zone transfers SHOULD be authenticated using TSIG [RFC8945]. A primary nameserver SHOULD NOT serve a catalog zone for transfer without using TSIG and a secondary nameserver SHOULD abandon an update to a catalog zone that was received without using TSIG. Use of DNS UPDATE [RFC2136] to modify the content of catalog zones SHOULD similarly be authenticated using TSIG. van Dijk, et al. Expires 26 February 2022 [Page 14] Internet-Draft dns-catalog-zones August 2021 Zone transfers of member zones SHOULD similarly be authenticated using TSIG [RFC8945]. The TSIG shared secrets used for member zones MUST NOT be mentioned anywhere in the catalog zone data. However, key identifiers may be shared within catalog zones. Catalog zones reveal the zones served by the consumers of the catalog zone. It is RECOMMENDED to limit the systems able to query these zones. It is RECOMMENDED to transfer catalog zones confidentially [RFC9103]. Administrative control over what zones are served from the configured name servers shifts completely from the server operator (consumer) to the "owner" (producer) of the catalog zone content. 10. IANA Considerations 10.1. TIMESTAMP RR type This document defines a new DNS RR type, TIMESTAMP, in the "Resource Record (RR) TYPEs" subregistry of the "Domain Name System (DNS) Parameters" registry: +===========+=======+===========+=================+ | TYPE | Value | Meaning | Reference | +===========+=======+===========+=================+ | TIMESTAMP | TBD | Timestamp | [this document] | +-----------+-------+-----------+-----------------+ Table 1 10.2. SERIAL RR type This document defines a new DNS RR type, SERIAL, in the "Resource Record (RR) TYPEs" subregistry of the "Domain Name System (DNS) Parameters" registry: +========+=======+===========================+===========+ | TYPE | Value | Meaning | Reference | +========+=======+===========================+===========+ | SERIAL | TBD | Version number of the | [this | | | | original copy of the zone | document] | +--------+-------+---------------------------+-----------+ Table 2 van Dijk, et al. Expires 26 February 2022 [Page 15] Internet-Draft dns-catalog-zones August 2021 11. Acknowledgements Our deepest thanks and appreciation go to Stephen Morris, Ray Bellis and Witold Krecicki who initiated this draft and did the bulk of the work. Catalog zones originated as the chosen method among various proposals that were evaluated at ISC for easy zone management. The chosen method of storing the catalog as a regular DNS zone was proposed by Stephen Morris. The initial authors discovered that Paul Vixie's earlier [Metazones] proposal implemented a similar approach and reviewed it. Catalog zones borrows some syntax ideas from Metazones, as both share this scheme of representing the catalog as a regular DNS zone. Thanks to Brian Conry, Tony Finch, Evan Hunt, Patrik Lundin, Victoria Risk, Carsten Strotmann, Peter Thomassen and Kees Monshouwer for reviewing draft proposals and offering comments and suggestions. Thanks to Klaus Darilion who came up with the idea for the "serial" property during the hackathon at the IETF-109. Thanks also to Shane Kerr, Petr Spacek, Brian Dickson for further brainstorming and discussing the "serial" property and how it would work best with catalog zones. 12. Normative References [RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, November 1987, <https://www.rfc-editor.org/info/rfc1035>. [RFC1982] Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982, DOI 10.17487/RFC1982, August 1996, <https://www.rfc-editor.org/info/rfc1982>. [RFC1996] Vixie, P., "A Mechanism for Prompt Notification of Zone Changes (DNS NOTIFY)", RFC 1996, DOI 10.17487/RFC1996, August 1996, <https://www.rfc-editor.org/info/rfc1996>. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/info/rfc2119>. van Dijk, et al. Expires 26 February 2022 [Page 16] Internet-Draft dns-catalog-zones August 2021 [RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound, "Dynamic Updates in the Domain Name System (DNS UPDATE)", RFC 2136, DOI 10.17487/RFC2136, April 1997, <https://www.rfc-editor.org/info/rfc2136>. [RFC2606] Eastlake 3rd, D. and A. Panitz, "Reserved Top Level DNS Names", BCP 32, RFC 2606, DOI 10.17487/RFC2606, June 1999, <https://www.rfc-editor.org/info/rfc2606>. [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "Resource Records for the DNS Security Extensions", RFC 4034, DOI 10.17487/RFC4034, March 2005, <https://www.rfc-editor.org/info/rfc4034>. [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <https://www.rfc-editor.org/info/rfc8174>. [RFC8945] Dupont, F., Morris, S., Vixie, P., Eastlake 3rd, D., Gudmundsson, O., and B. Wellington, "Secret Key Transaction Authentication for DNS (TSIG)", STD 93, RFC 8945, DOI 10.17487/RFC8945, November 2020, <https://www.rfc-editor.org/info/rfc8945>. [RFC9103] Toorop, W., Dickinson, S., Sahib, S., Aras, P., and A. Mankin, "DNS Zone Transfer over TLS", RFC 9103, DOI 10.17487/RFC9103, August 2021, <https://www.rfc-editor.org/info/rfc9103>. 13. Informative References [Metazones] Vixie, P., "Federated Domain Name Service Using DNS Metazones", 2005, <http://ss.vix.su/~vixie/mz.pdf>. Appendix A. Change History (to be removed before final publication) * draft-muks-dnsop-dns-catalog-zones-00 | Initial public draft. * draft-muks-dnsop-dns-catalog-zones-01 | Added Witold, Ray as authors. Fixed typos, consistency issues. | Fixed references. Updated Area. Removed newly introduced custom | RR TYPEs. Changed schema version to 1. Changed TSIG requirement | from MUST to SHOULD. Removed restrictive language about use of | DNS QUERY. When zones are introduced into a catalog zone, a van Dijk, et al. Expires 26 February 2022 [Page 17] Internet-Draft dns-catalog-zones August 2021 | primary SHOULD first make the new zones available for transfers | first (instead of MUST). Updated examples, esp. use IPv6 in | examples per Fred Baker. Add catalog zone example. * draft-muks-dnsop-dns-catalog-zones-02 | Addressed some review comments by Patrik Lundin. * draft-muks-dnsop-dns-catalog-zones-03 | Revision bump. * draft-muks-dnsop-dns-catalog-zones-04 | Reordering of sections into more logical order. Separation of | multi-valued properties into their own category. * draft-toorop-dnsop-dns-catalog-zones-00 | New authors to pickup the editor pen on this draft | | Remove data type definitions for zone properties Removing | configuration of member zones through zone properties altogether | | Remove Open issues and discussion Appendix, which was about zone | options (including primary/secondary relationships) only. * draft-toorop-dnsop-dns-catalog-zones-01 | Added a new section "The Serial Property", introducing a new | mechanism which can help with disseminating zones from the primary | to the secondary nameservers in a timely fashion more reliably. | | Three different ways to provide a "serial" property with a member | zone are offered to or the workgroup for discussion. | | Added a new section "Implementation Status", listing production | ready, upcoming and Proof of Concept implementations, and | reporting on interoperability of the different implementations. * draft-toorop-dnsop-dns-catalog-zones-02 | Adding the "coo" property for zone migration in a controlled | fashion | | Adding the "group" property for reconfigure settings of member | zones in an atomic update | van Dijk, et al. Expires 26 February 2022 [Page 18] Internet-Draft dns-catalog-zones August 2021 | Adding the "epoch" property to reset zone associated state in a | controlled fashion * draft-toorop-dnsop-dns-catalog-zones-03 | Big cleanup! | | Introducing the terms catalog zone consumer and catalog zone | producer | | Reorganized topics to create a more coherent whole | | Properties all have consistent format now | | Try to assume the least possible from implementations w.r.t.: | | 1) Predictability of the <unique-N> IDs of member zones | | 2) Whether or not fallback catalog zones can be found for a member | | 3) Whether or not a catalog zone consumer can maintain state Authors' Addresses Peter van Dijk PowerDNS Den Haag Netherlands Email: firstname.lastname@example.org Libor Peltan CZ.NIC Czechia Email: email@example.com Ondrej Sury Internet Systems Consortium Czechia Email: firstname.lastname@example.org van Dijk, et al. Expires 26 February 2022 [Page 19] Internet-Draft dns-catalog-zones August 2021 Willem Toorop NLnet Labs Science Park 400 1098 XH Amsterdam Netherlands Email: email@example.com Leo Vandewoestijne Netherlands Email: firstname.lastname@example.org van Dijk, et al. Expires 26 February 2022 [Page 20]