| Internet Engineering Task Force | D. Wessels |
| Internet-Draft | P. Barber |
| Intended status: Standards Track | Verisign |
| Expires: December 14, 2020 | M. Weinberg |
| Amazon | |
| W. Kumari | |
| W. Hardaker | |
| USC/ISI | |
| June 12, 2020 |
Message Digest for DNS Zones
draft-ietf-dnsop-dns-zone-digest-08
This document describes a protocol and new DNS Resource Record that can be used to provide a cryptographic message digest over DNS zone data. The ZONEMD Resource Record conveys the digest data in the zone itself. When a zone publisher includes an ZONEMD record, recipients can verify the zone contents for accuracy and completeness. This provides assurance that received zone data matches published data, regardless of how the zone data has been transmitted and received.
ZONEMD is not designed to replace DNSSEC. Whereas DNSSEC protects individual RRSets (DNS data with fine granularity), ZONEMD protects a zone's data as a whole, whether consumed by authoritative name servers, recursive name servers, or any other applications.
As specified at this time, ZONEMD is not designed for use in large, dynamic zones due to the time and resources required for digest calculation. The ZONEMD record described in this document is designed so that new digest schemes may be developed in the future to support large, dynamic zones.
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 December 14, 2020.
Copyright (c) 2020 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 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.
In the DNS, a zone is the collection of authoritative resource records (RRs) sharing a common origin ([RFC8499]). Zones are often stored as files on disk in the so-called master file format [RFC1034]. Zones are generally distributed among name servers using the AXFR [RFC5936], and IXFR [RFC1995] protocols. Zone files can also be distributed outside of the DNS, with such protocols as FTP, HTTP, rsync, and even via email. Currently there is no standard way to verify the authenticity of a stand-alone zone.
This document introduces a new RR type that serves as a cryptographic message digest of the data in a zone. It allows a receiver of the zone to verify the zone's authenticity, especially when used in combination with DNSSEC. This technique makes the digest a part of the zone itself, allowing verification the zone as a whole, no matter how it is transmitted. Furthermore, the digest is based on the wire format of zone data. Thus, it is independent of presentation format, such as changes in whitespace, capitalization, and comments.
DNSSEC provides three strong security guarantees relevant to this protocol:
This specification is OPTIONAL to implement by both publishers and consumers of zone data.
The motivation for this protocol enhancement is the desire for the ability to verify the authenticity of a stand-alone zone, regardless of how it is transmitted. A consumer of zone data should be able to verify that the data is as-published by the zone operator.
One approach to preventing data tampering and corruption is to secure the distribution channel. The DNS has a number of features that can already be used for channel security. Perhaps the most widely used is DNS transaction signatures (TSIG [RFC2845]). TSIG uses shared secret keys and a message digest to protect individual query and response messages. It is generally used to authenticate and validate UPDATE [RFC2136], AXFR [RFC5936], and IXFR [RFC1995] messages.
DNS Request and Transaction Signatures (SIG(0) [RFC2931]) is another protocol extension designed to authenticate individual DNS transactions. Whereas SIG records were originally designed to cover specific RR types, SIG(0) is used to sign an entire DNS message. Unlike TSIG, SIG(0) uses public key cryptography rather than shared secrets.
The Transport Layer Security protocol suite is also designed to provide channel security. One can easily imagine the distribution of zones over HTTPS-enabled web servers, as well as DNS-over-HTTPS [RFC8484], and perhaps even a future version of DNS-over-TLS ([RFC7858]).
Unfortunately, the protections provided by these channel security techniques are (in practice) ephemeral and are not retained after the data transfer is complete. They can ensure that the client receives the data from the expected server, and that the data sent by the server is not modified during transmission. However, they do not guarantee that the server transmits the data as originally published, and do not provide any methods to verify data that is read after transmission is complete. For example, a name server loading saved zone data upon restart cannot guarantee that the on-disk data has not been modified. For these reasons, it is preferable to secure the data itself.
Why not simply rely on DNSSEC, which provides certain data security guarantees? Certainly for zones that are signed, a recipient could validate all of the signed RRSets. Additionally, denial-of-existence records can prove that RRSets have not been added or removed. However, not all RRSets in a zone are signed. The design of DNSSEC stipulates that delegations (non-apex NS records) are not signed, and neither are any glue records. ZONEMD protects the integrity of delegation, glue, and other records that are not otherwise covered by DNSSEC. Furthermore, zones that employ NSEC3 with opt-out are susceptible to the removal or addition of names between the signed nodes. Whereas DNSSEC is primarily designed to protect consumers of DNS response messages, this protocol is designed to protect consumers of zones.
There are existing tools and protocols that provide data security, such as OpenPGP [RFC4880] and S/MIME [RFC5751]. In fact, the internic.net site publishes PGP signatures along side the root zone and other files available there. However, this is a detached signature with no strong association to the corresponding zone file other than its timestamp. Non-detached signatures are, of course, possible, but these necessarily change the format of the file being distributed. That is, a zone signed with OpenPGP or S/MIME no longer looks like a DNS zone and could not directly be loaded into a name server. Once loaded the signature data is lost, so it does not survive further propagation.
It seems the desire for data security in DNS zones was envisioned as far back as 1997. [RFC2065] is an obsoleted specification of the first generation DNSSEC Security Extensions. It describes a zone transfer signature, aka AXFR SIG, which is similar to the technique proposed by this document. That is, it proposes ordering all (signed) RRSets in a zone, hashing their contents, and then signing the zone hash. The AXFR SIG is described only for use during zone transfers. It did not postulate the need to validate zone data distributed outside of the DNS. Furthermore, its successor, [RFC2535], omits the AXFR SIG, while at the same time introducing an IXFR SIG.
This document introduces a new Resource Record type designed to convey a message digest of the content of a zone. The digest is calculated at the time of zone publication. Ideally the zone is signed with DNSSEC to guarantee that any modifications of the digest can be detected. The procedures for digest calculation and DNSSEC signing are similar. Both require data to be processed in a well-defined order and format. In some cases it may be possible to perform DNSSEC signing and digest calculation in parallel.
The zone digest is designed to be used on zones that are relatively stable and have infrequent updates. As currently specified, the digest is re-calculated over the entire zone content each time. This specification does not provide an efficient mechanism for incremental updates of zone data. It is, however, extensible so that future schemes to support incremental zone digest algorithms (e.g. using Merkle trees) can be accommodated.
It is expected that verification of a zone digest would be implemented in name server software. That is, a name server can verify the zone data it was given and refuse to serve a zone which fails verification. For signed zones, the name server needs a trust anchor to perform DNSSEC validation. For signed non-root zones, the name server may need to send queries to validate a chain-of-trust. Digest verification could also be performed externally.
The root zone [InterNIC] is one of the most widely distributed DNS zone on the Internet, served by more than 1000 separate instances [RootServers] at the time of this writing. Additionally, many organizations configure their own name servers to serve the root zone locally. Reasons for doing so include privacy and reduced access time. [RFC7706] describes one, but not the only, way to do this. As the root zone spreads beyond its traditional deployment boundaries, the need for verification of the completeness of the zone contents becomes increasingly important.
Since its very early days, the developers of the DNS recognized the importance of secondary name servers and service diversity. However, they may not have anticipated the complexity of modern DNS service provisioning which can include multiple third-party providers and hundreds of anycast instances. Instead of a simple primary-to-secondary zone distribution system, today it is possible to have multiple levels, multiple parties, and multiple protocols involved in the distribution of zone data. This complexity introduces new places for problems to arise. The zone digest protects the integrity of data that flows through such systems.
DNS Response Policy Zones is "a method of expressing DNS response policy information inside specially constructed DNS zones..." [RPZ]. A number of companies provide RPZ feeds, which can be consumed by name server and firewall products. Since these are zones, AXFR is often, but not necessarily used for transmission. While RPZ zones can certainly be signed with DNSSEC, the data is not queried directly, and would not be subject to DNSSEC validation.
ICANN operates the Centralized Zone Data Service [CZDS], which is a repository of top-level domain zone files. Users request access to the system, and to individual zones, and are then able to download zone data for certain uses. Adding a zone digest to these would provide CZDS users with assurances that the data has not been modified. Note that ZONEMD could be added to CZDS zone data independently of the zone served by production name servers.
Since the zone digest calculation does not depend on presentation format, it could be used to compare multiple copies of a zone received from different sources, or copies generated by different processes.
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.
This section describes the ZONEMD Resource Record, including its fields, wire format, and presentation format. The Type value for the ZONEMD RR is 63. The ZONEMD RR is class independent. The RDATA of the resource record consists of four fields: Serial, Scheme, Hash Algorithm, and Digest.
A zone MAY contain multiple ZONEMD RRs to support algorithm agility [RFC7696] and rollovers. Each ZONEMD RR must specify a unique Scheme and Hash Algorithm tuple. It is recommended that a zone include only one ZONEMD RR, unless the zone publisher is in the process of transitioning to a new Scheme or Hash Algorithm.
This specification utilizes ZONEMD RRs located at the zone apex. Non-apex ZONEMD RRs are not forbidden, but have no meaning in this specification. Non-apex ZONEMD RRs MUST NOT be used for verification.
During digest calculation, non-apex ZONEMD RRs are treated like any other RRs. They are digested as-is and the RR is not replaced by a placeholder RR.
Unless explicitly stated otherwise, "ZONEMD" always refers to apex records throughout this document.
The ZONEMD 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scheme |Hash Algorithm | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Digest |
/ /
/ /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Serial field is a 32-bit unsigned integer in network order. It is equal to the serial number from the zone's SOA record ([RFC1035] section 3.3.13) for which the zone digest was generated.
The zone's serial number is included here in order to make DNS response messages of type ZONEMD meaningful. Without the serial number, a stand-alone ZONEMD digest has no association to any particular instance of a zone.
The Scheme field is an 8-bit unsigned integer that identifies the methods by which data is collated and presented as input to the hashing function.
At the time of this writing, SIMPLE, with value 1, is the only standardized Scheme defined for ZONEMD records. The Scheme registry is further described in Section 5.
Scheme values 240-254 are allocated for Private Use as described in [RFC8126].
The Hash Algorithm field is an 8-bit unsigned integer that identifies the cryptographic hash algorithm used to construct the digest.
At the time of this writing, SHA384, with value 1, is the only standardized Hash Algorithm defined for ZONEMD records. The Hash Algorithm registry is further described in Section 5.
Hash Algorithm values 240-254 are allocated for Private Use as described in [RFC8126].
The Digest field is a variable-length sequence of octets containing the output of the hash algorithm. The Digest field must not be empty. Section 3 describes how to calculate the digest for a zone. Section 4 describes how to use the digest to verify the contents of a zone.
The presentation format of the RDATA portion is as follows:
The Serial field is represented as an unsigned decimal integer.
The Scheme field is represented as an unsigned decimal integer.
The Hash Algorithm field is represented as an unsigned decimal integer.
The Digest is represented as a sequence of case-insensitive hexadecimal digits. Whitespace is allowed within the hexadecimal text.
The following example shows a ZONEMD RR.
example.com. 86400 IN ZONEMD 2018031500 1 1 (
FEBE3D4CE2EC2FFA4BA99D46CD69D6D29711E55217057BEE
7EB1A7B641A47BA7FED2DD5B97AE499FAFA4F22C6BD647DE )
In preparation for calculating the zone digest, any existing ZONEMD records (and covering RRSIGs) at the zone apex are first deleted.
Prior to calculation of the digest, and prior to signing with DNSSEC, one or more placeholder ZONEMD records are added to the zone apex. This ensures that denial-of-existence (NSEC, NSEC3) records are created correctly if the zone is signed with DNSSEC. If placeholders are not added prior to signing, the later addition of ZONEMD records would also require updating the Type Bit Maps field of any apex NSEC/NSEC3 RRs, which then invalidates the calculated digest value.
When multiple ZONEMD RRs are published in the zone, e.g., during an algorithm rollover, each must specify a unique Scheme and Hash Algorithm tuple.
It is recommended that the TTL of the ZONEMD record match the TTL of the SOA.
In the placeholder record, the Serial field is set to the current SOA Serial. The Scheme field is set to the value for the chosen collation scheme. The Hash Algorithm field is set to the value for the chosen hash algorithm. Since ZONEMD records are excluded from digest calculation, the value of the Digest field does not matter at this point in the process. Implementations MAY want to set the Digest field to all zeroes anyway.
Following addition of placeholder records, the zone may be signed with DNSSEC. Note that when the digest calculation is complete, and the ZONEMD record is updated, the signature(s) for the ZONEMD RRSet MUST be recalculated and updated as well. Therefore, the signer is not required to calculate a signature over the placeholder record at this step in the process, but it is harmless to do so.
Calculation of a zone digest REQUIRES RRs to be processed in a consistent format and ordering. Correct ordering depends on (1) ordering of owner names, (2) ordering of RRSets with the same owner name, and (3) ordering of RRs within an RRSet.
This specification adopts DNSSEC's canonical ordering for names (Section 6.1 of [RFC4034]), and canonical ordering for RRs within an RRSet (Section 6.3 of [RFC4034]). It also adopts DNSSEC's canonical RR form (Section 6.2 of [RFC4034]).
However, since DNSSEC does not define a canonical ordering for RRSets having the same owner name, that ordering is defined here. For the purposes of calculating the zone digest, RRSets having the same owner name MUST be numerically ordered, in ascending order, by their numeric RR TYPE.
This specification adopts DNSSEC's canonical on-the-wire RR format (without name compression) as specified in [RFC4034]:
RR(i) = owner | type | class | TTL | RDATA length | RDATA
where "|" denotes concatenation.
When iterating over records in the zone, the following inclusion/exclusion rules apply:
At this time, only the SIMPLE collation scheme is defined. Additional schemes may be defined in future updates to this document.
For the SIMPLE scheme, the digest is calculated over the zone as a whole. This means that a change to a single RR in the zone requires iterating over all RRs in the zone to recalculate the digest. SIMPLE is a good choice for zones that are small and/or stable, but probably not good for zones that are large and/or dynamic.
A zone digest using the SIMPLE scheme is calculated by concatenating the canonical form of all RRs in the zone, in the order described in Section 3.3, subject to the inclusion/exclusion rules described in Section 3.4, and then applying the SHA-384 algorithm:
digest = hash( RR(1) | RR(2) | RR(3) | ... )
where "|" denotes concatenation.
Once a zone digest has been calculated, the published ZONEMD record is finalised by inserting the digest into the placeholder ZONEMD. Repeat for each digest if multiple digests are to be published.
If the zone is signed with DNSSEC, the RRSIG record(s) covering the ZONEMD RRSet MUST then be added or updated. Because the ZONEMD placeholder was added prior to signing, the zone will already have the appropriate denial-of-existence (NSEC, NSEC3) records.
Some DNSSEC implementations (especially "online signing") might be designed such that the SOA serial number is updated whenever a new signature is made. To preserve the calculated digest, generation of an ZONEMD signature must not also result in a change to the SOA serial number. The ZONEMD RR and the matching SOA MUST be published at the same time.
The recipient of a zone that has a ZONEMD RR can verify the zone by calculating the digest as follows. If multiple ZONEMD RRs are present in the zone, e.g., during an algorithm rollover, a match using any one of the recipient's supported Schemes and Hash Algorithms is sufficient to verify the zone.
This document defines a new DNS RR type, ZONEMD, whose value 63 has been allocated by IANA from the "Resource Record (RR) TYPEs" subregistry of the "Domain Name System (DNS) Parameters" registry:
Type: ZONEMD
Value: 63
Meaning: Message Digest Over Zone Data
Reference: This document
This document asks IANA to create a new "ZONEMD Scheme" registry with initial contents as follows:
| Value | Description | Mnemonic | Status | Reference |
|---|---|---|---|---|
| 0 | Reserved | RESERVED | N/A | N/A |
| 1 | Simple ZONEMD collation | SIMPLE | Mandatory | This document |
| 240-254 | Private Use | N/A | N/A | [RFC8126] |
The IANA policy for assigning new values to the ZONEMD Scheme registry shall be Specification Required, as described in [RFC8126].
This document asks IANA to create a new "ZONEMD Hash Algorithm" registry with initial contents as follows:
| Value | Description | Mnemonic | Status | Reference |
|---|---|---|---|---|
| 0 | Reserved | RESERVED | N/A | N/A |
| 1 | The SHA-384 hash algorithm | SHA384 | Mandatory | [RFC6234] |
| 240-254 | Private Use | N/A | N/A | [RFC8126] |
The IANA policy for assigning new values to the ZONEMD Hash Algorithm registry shall be Specification Required, as described in [RFC8126].
The zone digest allows the receiver to verify that the zone contents haven't been modified since the zone was generated/published. Verification is strongest when the zone is also signed with DNSSEC. An attacker, whose goal is to modify zone content before it is used by the victim, may consider a number of different approaches.
The attacker might perform a downgrade attack to an unsigned zone. This is why Section 4 talks about determining whether or not to expect DNSSEC signatures for the zone in step 1.
The attacker might perform a downgrade attack by removing one or more ZONEMD records. Such a removal is detectable only with DNSSEC validation and is why Section 4 talks about checking denial-of-existence proofs in step 2 and signature validation in step 3.
The attacker might alter the Scheme, Hash Algorithm, or Digest fields of the ZONEMD record. Such modifications are detectable only with DNSSEC validation.
Nothing in this specification prevents clients from making, and servers from responding to, ZONEMD queries. Servers SHOULD NOT calculate zone digests dynamically (for each query) as this can be used as a CPU resource exhaustion attack.
One might consider how well ZONEMD responses could be used in a distributed denial-of-service amplification attack. The ZONEMD RR is moderately sized, much like the DS RR. A single ZONEMD RR contributes approximately 40 to 65 octets to a DNS response, for currently defined digest types. Certainly other RR types result in larger amplification effects (i.e., DNSKEY).
ZONEMD can be used to detect incomplete or corrupted zone data prior to its use, thereby increasing resilience, but also introducing some fragility. Publishers and consumers of zones containing ZONEMD records should be aware of these tradeoffs. While the intention is to secure the zone data, misconfigurations or implementation bugs are generally indistinguishable from intentional tampering, and could lead to service failures when verification is performed automatically.
Zone publishers may want to deploy ZONEMD gradually, perhaps by utilizing one of the private use hash algorithms listed in Section 5.3. Similarly, recipients may want to initially configure verification failures only as a warning, and later as an error after gaining experience and confidence with the feature.
This section is provided to make zone publishers aware of the performance requirements and implications of including ZONEMD RRs in a zone.
As mentioned previously, the SIMPLE scheme may not be appropriate for use in zones that are either large or highly dynamic. Zone publishers should carefully consider the use of ZONEMD in such zones, since it might cause consumers of zone data (e.g., secondary name servers) to expend resources on digest calculation. Furthermore, for such use cases, it is recommended that ZONEMD only be used when digest calculation time is significantly less than propagation times and update intervals.
The authors' implementation (Section 10.1) includes an option to record and report CPU usage of its operation. The software was used to generate digests for more than 800 TLD zones available from [CZDS]. The table below summarizes the the results for the SIMPLE scheme and SHA384 hash algorithm grouped by zone size. The Rate column is the mean amount of time per RR to calculate the digest, running on commodity hardware at the time of this writing.
| Zone Size (RRs) | Rate (msec/RR) |
|---|---|
| 10 - 99 | 0.00683 |
| 100 - 999 | 0.00551 |
| 1000 - 9999 | 0.00505 |
| 10000 - 99999 | 0.00602 |
| 100000 - 999999 | 0.00845 |
| 1000000 - 9999999 | 0.0108 |
| 10000000 - 99999999 | 0.0148 |
For example, based on the above table, it takes approximately 0.13 seconds to calculate a SIMPLE SHA384 digest for a zone with 22,000 RRs, and about 2.5 seconds for a zone with 300,000 RRs.
These benchmarks attempt to emulate a worst-case scenario and take into account the time required to canonicalize the zone for processing. Each of the 800+ zones were measured three times, and then averaged, with a different random sorting of the input data prior to each measurement.
This specification has no impact on user privacy.
The authors wish to thank David Blacka, Scott Hollenbeck, and Rick Wilhelm for providing feedback on early drafts of this document. Additionally, they thank Joe Abley, Mark Andrews, Ralph Dolmans, Richard Gibson, Olafur Gudmundsson, Bob Harold, Paul Hoffman, Evan Hunt, Shumon Huque, Tatuya Jinmei, Mike St. Johns, Burt Kaliski, Shane Kerr, Matt Larson, John Levine, Ed Lewis, Matt Pounsett, Mukund Sivaraman, Petr Spacek, Ondrej Sury, Willem Toorop, Florian Weimer, Tim Wicinksi, Wouter Wijngarrds, Paul Wouters, and other members of the dnsop working group for their input.
The authors have an open source implementation in C, using the ldns library [ldns-zone-digest]. This implementation is able to perform the following functions:
This implementation does not:
Shane Kerr wrote an implementation of this specification during the IETF 102 hackathon [ZoneDigestHackathon]. This implementation is in Python and is able to perform the following functions:
This implementation does not:
NIC Chile Labs wrote an implementation of this specification as part of "dns-tools" suite [DnsTools], which besides digesting, can also sign and verify zones. This implementation is in Go and is able to perform the following functions:
RFC Editor: Please remove this section.
This section lists substantial changes to the document as it is being worked on.
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| [RFC1034] | Mockapetris, P., "Domain names - concepts and facilities", STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987. |
| [RFC1035] | Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, November 1987. |
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997. |
| [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. |
| [RFC6234] | Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms (SHA and SHA-based HMAC and HKDF)", RFC 6234, DOI 10.17487/RFC6234, May 2011. |
| [RFC8174] | Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017. |
This appendix contains example zones with accurate ZONEMD records. These can be used to verify an implementation of the zone digest protocol.
Here, the EXAMPLE zone contains an SOA record, NS and glue records, and a ZONEMD record.
example. 86400 IN SOA ns1 admin 2018031900 (
1800 900 604800 86400 )
86400 IN NS ns1
86400 IN NS ns2
86400 IN ZONEMD 2018031900 1 1 (
c68090d90a7aed71
6bc459f9340e3d7c
1370d4d24b7e2fc3
a1ddc0b9a87153b9
a9713b3c9ae5cc27
777f98b8e730044c )
ns1 3600 IN A 203.0.113.63
ns2 3600 IN AAAA 2001:db8::63
Here, the EXAMPLE zone contains duplicate RRs, and an occluded RR, and one out-of-zone RR.
example. 86400 IN SOA ns1 admin 2018031900 (
1800 900 604800 86400 )
86400 IN NS ns1
86400 IN NS ns2
86400 IN ZONEMD 2018031900 1 1 (
31cefb03814f5062
ad12fa951ba0ef5f
8da6ae354a415767
246f7dc932ceb1e7
42a2108f529db6a3
3a11c01493de358d )
ns1 3600 IN A 203.0.113.63
ns2 3600 IN AAAA 2001:db8::63
occluded.sub 7200 IN TXT "I'm occluded but must be digested"
sub 7200 IN NS ns1
duplicate 300 IN TXT "I must be digested just once"
duplicate 300 IN TXT "I must be digested just once"
foo.test. 555 IN TXT "out-of-zone data must be excluded"
non-apex 900 IN ZONEMD 2018031900 1 1 (
616c6c6f77656420
6275742069676e6f
7265642e20616c6c
6f77656420627574
2069676e6f726564
2e20616c6c6f7765 )
Here, the EXAMPLE zone contains multiple ZONEMD records. Since only one Scheme (SIMPLE) and one Hash Algorithm (SHA384) is defined at this time, this example utilizes additional ZONEMD records with Scheme and Hash Algorithm values in the private range (240-254). These additional private-range digests are not verifiable.
example. 86400 IN SOA ns1 admin 2018031900 (
1800 900 604800 86400 )
example. 86400 IN NS ns1.example.
example. 86400 IN NS ns2.example.
example. 86400 IN ZONEMD 2018031900 1 1 (
62e6cf51b02e54b9
b5f967d547ce4313
6792901f9f88e637
493daaf401c92c27
9dd10f0edb1c56f8
080211f8480ee306 )
example. 86400 IN ZONEMD 2018031900 1 240 (
e2d523f654b9422a
96c5a8f44607bbee )
example. 86400 IN ZONEMD 2018031900 241 1 (
e1846540e33a9e41
89792d18d5d131f6
05fc283e )
ns1.example. 3600 IN A 203.0.113.63
ns2.example. 86400 IN TXT "This example has multiple digests"
ns2.example. 3600 IN AAAA 2001:db8::63
The URI.ARPA zone retrieved 2018-10-21. Note this sample zone has (expired) signatures, but no signature for the ZONEMD RR.
; <<>> DiG 9.9.4 <<>> @lax.xfr.dns.icann.org uri.arpa axfr
; (2 servers found)
;; global options: +cmd
uri.arpa. 3600 IN SOA sns.dns.icann.org. (
noc.dns.icann.org. 2018100702 10800 3600 1209600 3600 )
uri.arpa. 3600 IN RRSIG NSEC 8 2 3600 (
20181028142623 20181007205525 47155 uri.arpa.
eEC4w/oXLR1Epwgv4MBiDtSBsXhqrJVvJWUpbX8XpetAvD35bxwNCUTi
/pAJVUXefegWeiriD2rkTgCBCMmn7YQIm3gdR+HjY/+o3BXNQnz97f+e
HAE9EDDzoNVfL1PyV/2fde9tDeUuAGVVwmD399NGq9jWYMRpyri2kysr q/g= )
uri.arpa. 86400 IN RRSIG NS 8 2 86400 (
20181028172020 20181007175821 47155 uri.arpa.
ATyV2A2A8ZoggC+68u4GuP5MOUuR+2rr3eWOkEU55zAHld/7FiBxl4ln
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Bsvs2b1qDZemBfkz/IfAhUTJKnto0vSUicJKfItu0GjyYNJCz2CqEuGD Wxc= )
uri.arpa. 600 IN RRSIG MX 8 2 600 (
20181028170556 20181007175821 47155 uri.arpa.
e7/r3KXDohX1lyVavetFFObp8fB8aXT76HnN9KCQDxSnSghNM83UQV0t
lTtD8JVeN1mCvcNFZpagwIgB7XhTtm6Beur/m5ES+4uSnVeS6Q66HBZK
A3mR95IpevuVIZvvJ+GcCAQpBo6KRODYvJ/c/ZG6sfYWkZ7qg/Em5/+3 4UI= )
uri.arpa. 3600 IN RRSIG DNSKEY 8 2 3600 (
20181028152832 20181007175821 15796 uri.arpa.
nzpbnh0OqsgBBP8St28pLvPEQ3wZAUdEBuUwil+rtjjWlYYiqjPxZ286
XF4Rq1usfV5x71jZz5IqswOaQgia91ylodFpLuXD6FTGs2nXGhNKkg1V
chHgtwj70mXU72GefVgo8TxrFYzxuEFP5ZTP92t97FVWVVyyFd86sbbR
6DZj3uA2wEvqBVLECgJLrMQ9Yy7MueJl3UA4h4E6zO2JY9Yp0W9woq0B
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uFPm0KD9U77Ac+ZtctAF9tsZwSdAoL365E2L1usZbA+K0BnPPqGFJRJk
5R0A1w== )
uri.arpa. 3600 IN RRSIG DNSKEY 8 2 3600 (
20181028152832 20181007175821 55480 uri.arpa.
lWtQV/5szQjkXmbcD47/+rOW8kJPksRFHlzxxmzt906+DBYyfrH6uq5X
nHvrUlQO6M12uhqDeL+bDFVgqSpNy+42/OaZvaK3J8EzPZVBHPJykKMV
63T83aAiJrAyHzOaEdmzLCpalqcEE2ImzlLHSafManRfJL8Yuv+JDZFj
2WDWfEcUuwkmIZWX11zxp+DxwzyUlRl7x4+ok5iKZWIg5UnBAf6B8T75
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1HeBfw== )
uri.arpa. 3600 IN RRSIG SOA 8 2 3600 (
20181029114753 20181008222815 47155 uri.arpa.
qn8yBNoHDjGdT79U2Wu9IIahoS0YPOgYP8lG+qwPcrZ1BwGiHywuoUa2
Mx6BWZlg+HDyaxj2iOmox+IIqoUHhXUbO7IUkJFlgrOKCgAR2twDHrXu
9BUQHy9SoV16wYm3kBTEPyxW5FFm8vcdnKAF7sxSY8BbaYNpRIEjDx4A JUc= )
uri.arpa. 3600 IN NSEC ftp.uri.arpa. NS SOA (
MX RRSIG NSEC DNSKEY )
uri.arpa. 86400 IN NS a.iana-servers.net.
uri.arpa. 86400 IN NS b.iana-servers.net.
uri.arpa. 86400 IN NS c.iana-servers.net.
uri.arpa. 86400 IN NS ns2.lacnic.net.
uri.arpa. 86400 IN NS sec3.apnic.net.
uri.arpa. 600 IN MX 10 pechora.icann.org.
uri.arpa. 3600 IN DNSKEY 256 3 8 (
AwEAAcBi7tSart2J599zbYWspMNGN70IBWb4ziqyQYH9MTB/VCz6WyUK
uXunwiJJbbQ3bcLqTLWEw134B6cTMHrZpjTAb5WAwg4XcWUu8mdcPTiL
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SdJjlH0B )
uri.arpa. 3600 IN DNSKEY 257 3 8 (
AwEAAbNVv6ulgRdO31MtAehz7j3ALRjwZglWesnzvllQl/+hBRZr9QoY
cO2I+DkO4Q1NKxox4DUIxj8SxPO3GwDuOFR9q2/CFi2O0mZjafbdYtWc
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l3wpbp+Wpm8= )
uri.arpa. 3600 IN DNSKEY 257 3 8 (
AwEAAbwnFTakCvaUKsXji4mgmxZUJi1IygbnGahbkmFEa0L16J+TchKR
wcgzVfsxUGa2MmeA4hgkAooC3uy+tTmoMsgy8uq/JAj24DjiHzd46LfD
FK/qMidVqFpYSHeq2Vv5ojkuIsx4oe4KsafGWYNOczKZgH5loGjN2aJG
mrIm++XCphOskgCsQYl65MIzuXffzJyxlAuts+ecAIiVeqRaqQfr8LRU
7wIsLxinXirprtQrbor+EtvlHp9qXE6ARTZDzf4jvsNpKvLFZtmxzFf3
e/UJz5eHjpwDSiZL7xE8aE1o1nGfPtJx9ZnB3bapltaJ5wY+5XOCKgY0
xmJVvNQlwdE= )
ftp.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 (
20181028080856 20181007175821 47155 uri.arpa.
HClGAqPxzkYkAT7Q/QNtQeB6YrkP6EPOef+9Qo5/2zngwAewXEAQiyF9
jD1USJiroM11QqBS3v3aIdW/LXORs4Ez3hLcKNO1cKHsOuWAqzmE+BPP
Arfh8N95jqh/q6vpaB9UtMkQ53tM2fYU1GszOLN0knxbHgDHAh2axMGH lqM= )
ftp.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 (
20181028103644 20181007205525 47155 uri.arpa.
WoLi+vZzkxaoLr2IGZnwkRvcDf6KxiWQd1WZP/U+AWnV+7MiqsWPZaf0
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YxlQJ0uHOvx1ZHFCj6lAt1ACUIw04ZhMydTmi27c8MzEOMepvn7iH7r7 k7k= )
ftp.uri.arpa. 3600 IN NSEC http.uri.arpa. NAPTR (
RRSIG NSEC )
ftp.uri.arpa. 604800 IN NAPTR 0 0 "" "" (
"!^ftp://([^:/?#]*).*$!\\1!i" . )
http.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 (
20181029010647 20181007175821 47155 uri.arpa.
U03NntQ73LHWpfLmUK8nMsqkwVsOGW2KdsyuHYAjqQSZvKbtmbv7HBmE
H1+Ii3Z+wtfdMZBy5aC/6sHdx69BfZJs16xumycMlAy6325DKTQbIMN+
ift9GrKBC7cgCd2msF/uzSrYxxg4MJQzBPvlkwXnY3b7eJSlIXisBIn7 3b8= )
http.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 (
20181029011815 20181007205525 47155 uri.arpa.
T7mRrdag+WSmG+n22mtBSQ/0Y3v+rdDnfQV90LN5Fq32N5K2iYFajF7F
Tp56oOznytfcL4fHrqOE0wRc9NWOCCUec9C7Wa1gJQcllEvgoAM+L6f0
RsEjWq6+9jvlLKMXQv0xQuMX17338uoD/xiAFQSnDbiQKxwWMqVAimv5 7Zs= )
http.uri.arpa. 3600 IN NSEC mailto.uri.arpa. NAPTR (
RRSIG NSEC )
http.uri.arpa. 604800 IN NAPTR 0 0 "" "" (
"!^http://([^:/?#]*).*$!\\1!i" . )
mailto.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 (
20181028110727 20181007175821 47155 uri.arpa.
GvxzVL85rEukwGqtuLxek9ipwjBMfTOFIEyJ7afC8HxVMs6mfFa/nEM/
IdFvvFg+lcYoJSQYuSAVYFl3xPbgrxVSLK125QutCFMdC/YjuZEnq5cl
fQciMRD7R3+znZfm8d8u/snLV9w4D+lTBZrJJUBe1Efc8vum5vvV7819 ZoY= )
mailto.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 (
20181028141825 20181007205525 47155 uri.arpa.
MaADUgc3fc5v++M0YmqjGk3jBdfIA5RuP62hUSlPsFZO4k37erjIGCfF
j+g84yc+QgbSde0PQHszl9fE/+SU5ZXiS9YdcbzSZxp2erFpZOTchrpg
916T4vx6i59scodjb0l6bDyZ+mtIPrc1w6b4hUyOUTsDQoAJYxdfEuMg Vy4= )
mailto.uri.arpa. 3600 IN NSEC urn.uri.arpa. NAPTR (
RRSIG NSEC )
mailto.uri.arpa. 604800 IN NAPTR 0 0 "" "" (
"!^mailto:(.*)@(.*)$!\\2!i" . )
urn.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 (
20181028123243 20181007175821 47155 uri.arpa.
Hgsw4Deops1O8uWyELGe6hpR/OEqCnTHvahlwiQkHhO5CSEQrbhmFAWe
UOkmGAdTEYrSz+skLRQuITRMwzyFf4oUkZihGyhZyzHbcxWfuDc/Pd/9
DSl56gdeBwy1evn5wBTms8yWQVkNtphbJH395gRqZuaJs3LD/qTyJ5Dp LvA= )
urn.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 (
20181029071816 20181007205525 47155 uri.arpa.
ALIZD0vBqAQQt40GQ0Efaj8OCyE9xSRJRdyvyn/H/wZVXFRFKrQYrLAS
D/K7q6CMTOxTRCu2J8yes63WJiaJEdnh+dscXzZkmOg4n5PsgZbkvUSW
BiGtxvz5jNncM0xVbkjbtByrvJQAO1cU1mnlDKe1FmVB1uLpVdA9Ib4J hMU= )
urn.uri.arpa. 3600 IN NSEC uri.arpa. NAPTR RRSIG (
NSEC )
urn.uri.arpa. 604800 IN NAPTR 0 0 "" "" (
"/urn:([^:]+)/\\1/i" . )
uri.arpa. 3600 IN SOA sns.dns.icann.org. (
noc.dns.icann.org. 2018100702 10800 3600 1209600 3600 )
;; Query time: 66 msec
;; SERVER: 192.0.32.132#53(192.0.32.132)
;; WHEN: Sun Oct 21 20:39:28 UTC 2018
;; XFR size: 34 records (messages 1, bytes 3941)
uri.arpa. 3600 IN ZONEMD 2018100702 1 1 (
1291b78ddf7669b1a39d014d87626b709b55774c5d7d58fa
dc556439889a10eaf6f11d615900a4f996bd46279514e473 )
The ROOT-SERVERS.NET zone retreived 2018-10-21.
root-servers.net. 3600000 IN SOA a.root-servers.net. (
nstld.verisign-grs.com. 2018091100 14400 7200 1209600 3600000 )
root-servers.net. 3600000 IN NS a.root-servers.net.
root-servers.net. 3600000 IN NS b.root-servers.net.
root-servers.net. 3600000 IN NS c.root-servers.net.
root-servers.net. 3600000 IN NS d.root-servers.net.
root-servers.net. 3600000 IN NS e.root-servers.net.
root-servers.net. 3600000 IN NS f.root-servers.net.
root-servers.net. 3600000 IN NS g.root-servers.net.
root-servers.net. 3600000 IN NS h.root-servers.net.
root-servers.net. 3600000 IN NS i.root-servers.net.
root-servers.net. 3600000 IN NS j.root-servers.net.
root-servers.net. 3600000 IN NS k.root-servers.net.
root-servers.net. 3600000 IN NS l.root-servers.net.
root-servers.net. 3600000 IN NS m.root-servers.net.
a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
a.root-servers.net. 3600000 IN A 198.41.0.4
b.root-servers.net. 3600000 IN MX 20 mail.isi.edu.
b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
b.root-servers.net. 3600000 IN A 199.9.14.201
c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
c.root-servers.net. 3600000 IN A 192.33.4.12
d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
d.root-servers.net. 3600000 IN A 199.7.91.13
e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
e.root-servers.net. 3600000 IN A 192.203.230.10
f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
f.root-servers.net. 3600000 IN A 192.5.5.241
g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
g.root-servers.net. 3600000 IN A 192.112.36.4
h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
h.root-servers.net. 3600000 IN A 198.97.190.53
i.root-servers.net. 3600000 IN MX 10 mx.i.root-servers.org.
i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
i.root-servers.net. 3600000 IN A 192.36.148.17
j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
j.root-servers.net. 3600000 IN A 192.58.128.30
k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
k.root-servers.net. 3600000 IN A 193.0.14.129
l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
l.root-servers.net. 3600000 IN A 199.7.83.42
m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
m.root-servers.net. 3600000 IN A 202.12.27.33
root-servers.net. 3600000 IN SOA a.root-servers.net. (
nstld.verisign-grs.com. 2018091100 14400 7200 1209600 3600000 )
root-servers.net. 3600000 IN ZONEMD 2018091100 1 1 (
f1ca0ccd91bd5573d9f431c00ee0101b2545c97602be0a97
8a3b11dbfc1c776d5b3e86ae3d973d6b5349ba7f04340f79 )