Internet-Draft DNSSEC August 2022
Hoffman Expires 12 February 2023 [Page]
Network Working Group
Intended Status:
Best Current Practice
P. Hoffman

DNS Security Extensions (DNSSEC)


This document describes the DNS security extensions (commonly called "DNSSEC") that are specified RFCs 4033, 4034, 4035, and a handful of others. One purpose is to introduce all of the RFCs in one place so that the reader can understand the many aspects of DNSSEC. This document does not update any of those RFCs. Another purpose is to move DNSSEC to Best Current Practice status.

This document is currently maintained at Issues and pull requests are welcomed.

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

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 12 February 2023.

Table of Contents

1. Introduction

The core specification for what we know as DNSSEC (the combination of [RFC4033], [RFC4034], and [RFC4035]) describes a set of protocols that provide origin authentication to data in the DNS. [RFC6840] updates and extends those core RFCs, but does not fundamentally change the way that DNSSEC works.

This document lists many (but not all) of the RFCs that should be considered by someone creating an implementation of, or someone deploying, modern DNSSEC. It uses terminology from those documents without defining that terminology. It also points to the relevant IANA registries that relate to DNSSEC. It does not, however, point to standards that rely on zones needing to be signed by DNSSEC.

1.1. DNSSEC as a Best Current Practice

The DNSSEC set of protocols is widely considered the best current practice for adding origin authentication of data in the DNS. To date, no standards-track RFCs offer any other method for such origin authentication of data in the DNS.

Some observers note that, more than 15 years after the DNSSEC specification was published, it is still not widely deployed. Recent estimates are that fewer than 10% of the domain names used for web sites are signed, and only around a third of queries to recursive resolvers are validated. However, this low level of implementation does not affect whether DNSSEC is a best current practice; it just indicates that the value of deploying DNSSEC is often considered lower than the cost. Nonetheless, the significant deployment of DNSSEC beneath some top-level domains (TLDs), and the near-universal deployment of DNSSEC for the TLDs in the DNS root zone, demonstrate that DNSSEC is suitable for implementation by both ordinary and highly sophisticated domain owners.

1.2. Implementing DNSSEC

Developers of validating resolvers and authoritative servers, as well as operators of operators of validating resolvers and authoritative servers, need to know the parts of the DNSSEC protocol that would affect them. They should read the DNSSEC core documents, and probably at least be familiar with the extensions. Developers will probably need to be very familiar with the algorithm documents as well.

As a side note, some of the DNSSEC-related RFCs have significant errata, so reading the RFCs should also include looking for the related errata.

2. DNSSEC Core Documents

What we today call "DNSSEC" is formally version 3 of the DNSSEC specification. However, earlier versions of DNSSEC were thinly deployed and significantly less visible than the current DNSSEC specification. Throughout this document, "DNSSEC" means version 3 of the protocol initially defined in [RFC4033], [RFC4034], and [RFC4035].

The three initial core documents generally cover different topics:

At the time this set of core documents was published, someone could create a DNSSEC implementation of signing software, of an DNSSEC-aware authoritative server, and/or a DNSSEC-aware recursive resolver from the three core documents, the many documents that update them, plus a few older RFCs specifying the cryptography used. Those two older documents are:

It is important to note that later RFCs update the core documents. As just one example, [RFC9077] changes how TTL values are calculated in DNSSEC processing.

2.1. Addition to the DNSSEC Core

As with any major protocol, developers and operators discovered issues with the original core documents over the years. [RFC6840] is an omnibus update to the original core documents and thus itself has become a core document. In addition to covering new requirements from new DNSSEC RFCs, it describes many important security and interoperability issues that arose during the deployment of the initial specifications, particularly after the DNS root was signed in 2010. It also lists some errors in the examples of the core specifications.

[RFC6840] brings a few additions into the core of DNSSEC. It makes NSEC3 [RFC5155] as much a part of DNSSEC as NSEC is. It also makes the SHA-2 hash function defined in [RFC4509] and [RFC5702] part of the core as well.

3. Additional Cryptographic Algorithms and DNSSEC

Cryptography improves over time, and new algorithms get adopted by various Internet protocols. Two new signing algorithms have been adopted by the DNSSEC community: ECDSA [RFC6605] and EdDSA [RFC8080]. The GOST signing algorithm [RFC5933] was also adopted, but has seen very limited use, likely because it is a national algorithm specific to a very small number of countries.

Implementation developers who want to know which algorithms to implement in DNSSEC software should refer to [RFC8624]. Note that this specification is only about what algorithms should and should not be included in implementations: it is not advice for which algorithms that zone operators should and should not sign with, nor which algorithms recursive resolver operators should or should not validate.

4. Extensions to DNSSEC

The DNSSEC community has extended the DNSSEC core and the cryptographic algorithms both in terms of describing good operational practices and in new protocols. Some of the RFCs that describe these extensions include:

5. Additional Documents of Interest

The documents listed above constitute the core of DNSSEC, the additional cryptographic algorithms, and the major extensions to DNSSEC. This section lists some additional documents that someone interested in implementing or operating DNSSEC might find of value.

There will certainly be other RFCs related to DNSSEC that are published after this one.

6. IANA Considerations

IANA already has three registries that relate to DNSSEC:

The rules for the DNSSEC algorithm registry were set in the core RFCs and updated by [RFC6014], [RFC6725], and [RFC9157].

This document does not update or create any registries.

7. Security Considerations

All of the security considerations from all of the RFCs referenced in this document apply here.

8. References

8.1. Normative References

Eastlake 3rd, D., "RSA/SHA-1 SIGs and RSA KEYs in the Domain Name System (DNS)", RFC 3110, DOI 10.17487/RFC3110, , <>.
Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "DNS Security Introduction and Requirements", RFC 4033, DOI 10.17487/RFC4033, , <>.
Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "Resource Records for the DNS Security Extensions", RFC 4034, DOI 10.17487/RFC4034, , <>.
Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "Protocol Modifications for the DNS Security Extensions", RFC 4035, DOI 10.17487/RFC4035, , <>.
Hardaker, W., "Use of SHA-256 in DNSSEC Delegation Signer (DS) Resource Records (RRs)", RFC 4509, DOI 10.17487/RFC4509, , <>.
Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS Security (DNSSEC) Hashed Authenticated Denial of Existence", RFC 5155, DOI 10.17487/RFC5155, , <>.
Jansen, J., "Use of SHA-2 Algorithms with RSA in DNSKEY and RRSIG Resource Records for DNSSEC", RFC 5702, DOI 10.17487/RFC5702, , <>.
Weiler, S., Ed. and D. Blacka, Ed., "Clarifications and Implementation Notes for DNS Security (DNSSEC)", RFC 6840, DOI 10.17487/RFC6840, , <>.

8.2. Informative References

Eastlake 3rd, D., "DSA KEYs and SIGs in the Domain Name System (DNS)", RFC 2536, DOI 10.17487/RFC2536, , <>.
Weiler, S. and J. Ihren, "Minimally Covering NSEC Records and DNSSEC On-line Signing", RFC 4470, DOI 10.17487/RFC4470, , <>.
StJohns, M., "Automated Updates of DNS Security (DNSSEC) Trust Anchors", STD 74, RFC 5011, DOI 10.17487/RFC5011, , <>.
Dolmatov, V., Ed., Chuprina, A., and I. Ustinov, "Use of GOST Signature Algorithms in DNSKEY and RRSIG Resource Records for DNSSEC", RFC 5933, DOI 10.17487/RFC5933, , <>.
Hoffman, P., "Cryptographic Algorithm Identifier Allocation for DNSSEC", RFC 6014, DOI 10.17487/RFC6014, , <>.
Hoffman, P. and W.C.A. Wijngaards, "Elliptic Curve Digital Signature Algorithm (DSA) for DNSSEC", RFC 6605, DOI 10.17487/RFC6605, , <>.
Rose, S., "DNS Security (DNSSEC) DNSKEY Algorithm IANA Registry Updates", RFC 6725, DOI 10.17487/RFC6725, , <>.
Kolkman, O., Mekking, W., and R. Gieben, "DNSSEC Operational Practices, Version 2", RFC 6781, DOI 10.17487/RFC6781, , <>.
Crocker, S. and S. Rose, "Signaling Cryptographic Algorithm Understanding in DNS Security Extensions (DNSSEC)", RFC 6975, DOI 10.17487/RFC6975, , <>.
Gieben, R. and W. Mekking, "Authenticated Denial of Existence in the DNS", RFC 7129, DOI 10.17487/RFC7129, , <>.
Kumari, W., Gudmundsson, O., and G. Barwood, "Automating DNSSEC Delegation Trust Maintenance", RFC 7344, DOI 10.17487/RFC7344, , <>.
Morris, S., Ihren, J., Dickinson, J., and W. Mekking, "DNSSEC Key Rollover Timing Considerations", RFC 7583, DOI 10.17487/RFC7583, , <>.
Ebersman, P., Kumari, W., Griffiths, C., Livingood, J., and R. Weber, "Definition and Use of DNSSEC Negative Trust Anchors", RFC 7646, DOI 10.17487/RFC7646, , <>.
Abley, J., Schlyter, J., Bailey, G., and P. Hoffman, "DNSSEC Trust Anchor Publication for the Root Zone", RFC 7958, DOI 10.17487/RFC7958, , <>.
Hardaker, W., Gudmundsson, O., and S. Krishnaswamy, "DNSSEC Roadblock Avoidance", BCP 207, RFC 8027, DOI 10.17487/RFC8027, , <>.
Gudmundsson, O. and P. Wouters, "Managing DS Records from the Parent via CDS/CDNSKEY", RFC 8078, DOI 10.17487/RFC8078, , <>.
Sury, O. and R. Edmonds, "Edwards-Curve Digital Security Algorithm (EdDSA) for DNSSEC", RFC 8080, DOI 10.17487/RFC8080, , <>.
Wessels, D., Kumari, W., and P. Hoffman, "Signaling Trust Anchor Knowledge in DNS Security Extensions (DNSSEC)", RFC 8145, DOI 10.17487/RFC8145, , <>.
Fujiwara, K., Kato, A., and W. Kumari, "Aggressive Use of DNSSEC-Validated Cache", RFC 8198, DOI 10.17487/RFC8198, , <>.
Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499, , <>.
Huston, G., Damas, J., and W. Kumari, "A Root Key Trust Anchor Sentinel for DNSSEC", RFC 8509, DOI 10.17487/RFC8509, , <>.
Wouters, P. and O. Sury, "Algorithm Implementation Requirements and Usage Guidance for DNSSEC", RFC 8624, DOI 10.17487/RFC8624, , <>.
Huque, S., Aras, P., Dickinson, J., Vcelak, J., and D. Blacka, "Multi-Signer DNSSEC Models", RFC 8901, DOI 10.17487/RFC8901, , <>.
van Dijk, P., "NSEC and NSEC3: TTLs and Aggressive Use", RFC 9077, DOI 10.17487/RFC9077, , <>.
Hoffman, P., "Revised IANA Considerations for DNSSEC", RFC 9157, DOI 10.17487/RFC9157, , <>.
Hardaker, W. and V. Dukhovni, "Guidance for NSEC3 Parameter Settings", BCP 236, RFC 9276, DOI 10.17487/RFC9276, , <>.

Appendix A. Acknowledgements

The DNS world owes a depth of gratitude to the authors and other contributors to the core DNSSEC documents, and to the notable DNSSEC extensions.

In addition, the following people made significant contributions to early versions of this document: Ben Schwartz and Duane Wessels.

Author's Address

Paul Hoffman