Dnsext Workgroup RFCs

Browse Dnsext Workgroup RFCs by Number

RFC2782 - A DNS RR for specifying the location of services (DNS SRV): This document describes a DNS RR which specifies the location of the server(s) for a specific protocol and domain. [STANDARDS-TRACK]
RFC2845 - Secret Key Transaction Authentication for DNS (TSIG): This protocol allows for transaction level authentication using shared secrets and one way hashing. It can be used to authenticate dynamic updates as coming from an approved client, or to authenticate responses as coming from an approved recursive name server. [STANDARDS-TRACK]
RFC2929 - Domain Name System (DNS) IANA Considerations: This document discusses the Internet Assigned Number Authority (IANA) parameter assignment considerations given for the allocation of Domain Name System (DNS) classes, Resource Record (RR) types, operation codes, error codes, etc. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.
RFC2930 - Secret Key Establishment for DNS (TKEY RR): This document describes a Transaction Key (TKEY) RR that can be used in a number of different modes to establish shared secret keys between a DNS resolver and server. [STANDARDS-TRACK]
RFC2931 - DNS Request and Transaction Signatures ( SIG(0)s ): This document describes the minor but non-interoperable changes in Request and Transaction signature resource records ( SIG(0)s ) that implementation experience has deemed necessary. [STANDARDS-TRACK]
RFC3007 - Secure Domain Name System (DNS) Dynamic Update: This document proposes a method for performing secure Domain Name System (DNS) dynamic updates. [STANDARDS-TRACK]
RFC3008 - Domain Name System Security (DNSSEC) Signing Authority: This document proposes a revised model of Domain Name System Security (DNSSEC) Signing Authority. The revised model is designed to clarify earlier documents and add additional restrictions to simplify the secure resolution process. Specifically, this affects the authorization of keys to sign sets of records. [STANDARDS-TRACK]
RFC3090 - DNS Security Extension Clarification on Zone Status: The definition of a secured zone is presented, clarifying and updating sections of RFC 2535. RFC 2535 defines a zone to be secured based on a per algorithm basis, e.g., a zone can be secured with RSA keys, and not secured with DSA keys. This document changes this to define a zone to be secured or not secured regardless of the key algorithm used (or not used). To further simplify the determination of a zone's status, "experimentally secure" status is deprecated. [STANDARDS-TRACK]
RFC3110 - RSA/SHA-1 SIGs and RSA KEYs in the Domain Name System (DNS): This document describes how to produce RSA/SHA1 SIG resource records (RRs) in Section 3 and, so as to completely replace RFC 2537, describes how to produce RSA KEY RRs in Section 2. [STANDARDS-TRACK]
RFC3123 - A DNS RR Type for Lists of Address Prefixes (APL RR): The Domain Name System (DNS) is primarily used to translate domain names into IPv4 addresses using A RRs (Resource Records). Several approaches exist to describe networks or address ranges. This document specifies a new DNS RR type "APL" for address prefix lists. This memo defines an Experimental Protocol for the Internet community.
RFC3197 - Applicability Statement for DNS MIB Extensions: This document explains why, after more than six years as proposed standards, the DNS Server and Resolver MIB extensions were never deployed, and recommends retiring these MIB extensions by moving them to Historical status. This memo provides information for the Internet community.
RFC3225 - Indicating Resolver Support of DNSSEC: In order to deploy DNSSEC (Domain Name System Security Extensions) operationally, DNSSEC aware servers should only perform automatic inclusion of DNSSEC RRs when there is an explicit indication that the resolver can understand those RRs. This document proposes the use of a bit in the EDNS0 header to provide that explicit indication and describes the necessary protocol changes to implement that notification. [STANDARDS-TRACK]
RFC3226 - DNSSEC and IPv6 A6 aware server/resolver message size requirements: This document mandates support for EDNS0 (Extension Mechanisms for DNS) in DNS entities claiming to support either DNS Security Extensions or A6 records. This requirement is necessary because these new features increase the size of DNS messages. If EDNS0 is not supported fall back to TCP will happen, having a detrimental impact on query latency and DNS server load. This document updates RFC 2535 and RFC 2874, by adding new requirements. [STANDARDS-TRACK]
RFC3363 - Representing Internet Protocol version 6 (IPv6) Addresses in the Domain Name System (DNS)
RFC3364 - Tradeoffs in Domain Name System (DNS) Support for Internet Protocol version 6 (IPv6)
RFC3425 - Obsoleting IQUERY: The IQUERY method of performing inverse DNS lookups, specified in RFC 1035, has not been generally implemented and has usually been operationally disabled where it has been implemented. Both reflect a general view in the community that the concept was unwise and that the widely-used alternate approach of using pointer (PTR) queries and reverse-mapping records is preferable. Consequently, this document deprecates the IQUERY operation, declaring it entirely obsolete. This document updates RFC 1035. [STANDARDS-TRACK]
RFC3445 - Limiting the Scope of the KEY Resource Record (RR): This document limits the Domain Name System (DNS) KEY Resource Record (RR) to only keys used by the Domain Name System Security Extensions (DNSSEC). The original KEY RR used sub-typing to store both DNSSEC keys and arbitrary application keys. Storing both DNSSEC and application keys with the same record type is a mistake. This document removes application keys from the KEY record by redefining the Protocol Octet field in the KEY RR Data. As a result of removing application keys, all but one of the flags in the KEY record become unnecessary and are redefined. Three existing application key sub-types are changed to reserved, but the format of the KEY record is not changed. This document updates RFC 2535. [STANDARDS-TRACK]
RFC3596 - DNS Extensions to Support IP Version 6: This document defines the changes that need to be made to the Domain Name System (DNS) to support hosts running IP version 6 (IPv6). The changes include a resource record type to store an IPv6 address, a domain to support lookups based on an IPv6 address, and updated definitions of existing query types that return Internet addresses as part of additional section processing. The extensions are designed to be compatible with existing applications and, in particular, DNS implementations themselves. [STANDARDS-TRACK]
RFC3597 - Handling of Unknown DNS Resource Record (RR) Types: Extending the Domain Name System (DNS) with new Resource Record (RR) types currently requires changes to name server software. This document specifies the changes necessary to allow future DNS implementations to handle new RR types transparently. [STANDARDS-TRACK]
RFC3645 - Generic Security Service Algorithm for Secret Key Transaction Authentication for DNS (GSS-TSIG): The Secret Key Transaction Authentication for DNS (TSIG) protocol provides transaction level authentication for DNS. TSIG is extensible through the definition of new algorithms. This document specifies an algorithm based on the Generic Security Service Application Program Interface (GSS-API) (RFC2743). This document updates RFC 2845.
RFC3655 - Redefinition of DNS Authenticated Data (AD) bit: This document alters the specification defined in RFC 2535. Based on implementation experience, the Authenticated Data (AD) bit in the DNS header is not useful. This document redefines the AD bit such that it is only set if all answers or records proving that no answers exist in the response has been cryptographically verified or otherwise meets the server's local security policy.
RFC3658 - Delegation Signer (DS) Resource Record (RR): The delegation signer (DS) resource record (RR) is inserted at a zone cut (i.e., a delegation point) to indicate that the delegated zone is digitally signed and that the delegated zone recognizes the indicated key as a valid zone key for the delegated zone. The DS RR is a modification to the DNS Security Extensions definition, motivated by operational considerations. The intent is to use this resource record as an explicit statement about the delegation, rather than relying on inference. This document defines the DS RR, gives examples of how it is used and describes the implications on resolvers. This change is not backwards compatible with RFC 2535. This document updates RFC 1035, RFC 2535, RFC 3008 and RFC 3090.
RFC3755 - Legacy Resolver Compatibility for Delegation Signer (DS): As the DNS Security (DNSSEC) specifications have evolved, the syntax and semantics of the DNSSEC resource records (RRs) have changed. Many deployed nameservers understand variants of these semantics. Dangerous interactions can occur when a resolver that understands an earlier version of these semantics queries an authoritative server that understands the new delegation signer semantics, including at least one failure scenario that will cause an unsecured zone to be unresolvable. This document changes the type codes and mnemonics of the DNSSEC RRs (SIG, KEY, and NXT) to avoid those interactions. [STANDARDS-TRACK]
RFC3757 - Domain Name System KEY (DNSKEY) Resource Record (RR) Secure Entry Point (SEP) Flag: With the Delegation Signer (DS) resource record (RR), the concept of a public key acting as a secure entry point (SEP) has been introduced. During exchanges of public keys with the parent there is a need to differentiate SEP keys from other public keys in the Domain Name System KEY (DNSKEY) resource record set. A flag bit in the DNSKEY RR is defined to indicate that DNSKEY is to be used as a SEP. The flag bit is intended to assist in operational procedures to correctly generate DS resource records, or to indicate what DNSKEYs are intended for static configuration. The flag bit is not to be used in the DNS verification protocol. This document updates RFC 2535 and RFC 3755. [STANDARDS-TRACK]
RFC3833 - Threat Analysis of the Domain Name System (DNS): Although the DNS Security Extensions (DNSSEC) have been under development for most of the last decade, the IETF has never written down the specific set of threats against which DNSSEC is designed to protect. Among other drawbacks, this cart-before-the-horse situation has made it difficult to determine whether DNSSEC meets its design goals, since its design goals are not well specified. This note attempts to document some of the known threats to the DNS, and, in doing so, attempts to measure to what extent (if any) DNSSEC is a useful tool in defending against these threats. This memo provides information for the Internet community.
RFC3845 - DNS Security (DNSSEC) NextSECure (NSEC) RDATA Format: This document redefines the wire format of the "Type Bit Map" field in the DNS NextSECure (NSEC) resource record RDATA format to cover the full resource record (RR) type space. [STANDARDS-TRACK]
RFC4033 - DNS Security Introduction and Requirements: The Domain Name System Security Extensions (DNSSEC) add data origin authentication and data integrity to the Domain Name System. This document introduces these extensions and describes their capabilities and limitations. This document also discusses the services that the DNS security extensions do and do not provide. Last, this document describes the interrelationships between the documents that collectively describe DNSSEC. [STANDARDS-TRACK]
RFC4034 - Resource Records for the DNS Security Extensions: This document is part of a family of documents that describe the DNS Security Extensions (DNSSEC). The DNS Security Extensions are a collection of resource records and protocol modifications that provide source authentication for the DNS. This document defines the public key (DNSKEY), delegation signer (DS), resource record digital signature (RRSIG), and authenticated denial of existence (NSEC) resource records. The purpose and format of each resource record is described in detail, and an example of each resource record is given.; This document obsoletes RFC 2535 and incorporates changes from all updates to RFC 2535. [STANDARDS-TRACK]
RFC4035 - Protocol Modifications for the DNS Security Extensions: This document is part of a family of documents that describe the DNS Security Extensions (DNSSEC). The DNS Security Extensions are a collection of new resource records and protocol modifications that add data origin authentication and data integrity to the DNS. This document describes the DNSSEC protocol modifications. This document defines the concept of a signed zone, along with the requirements for serving and resolving by using DNSSEC. These techniques allow a security-aware resolver to authenticate both DNS resource records and authoritative DNS error indications.; This document obsoletes RFC 2535 and incorporates changes from all updates to RFC 2535. [STANDARDS-TRACK]
RFC4343 - Domain Name System (DNS) Case Insensitivity Clarification: Domain Name System (DNS) names are "case insensitive". This document explains exactly what that means and provides a clear specification of the rules. This clarification updates RFCs 1034, 1035, and 2181. [STANDARDS-TRACK]
RFC4398 - Storing Certificates in the Domain Name System (DNS): Cryptographic public keys are frequently published, and their authenticity is demonstrated by certificates. A CERT resource record (RR) is defined so that such certificates and related certificate revocation lists can be stored in the Domain Name System (DNS). [STANDARDS-TRACK]
RFC4470 - Minimally Covering NSEC Records and DNSSEC On-line Signing: This document describes how to construct DNSSEC NSEC resource records that cover a smaller range of names than called for by RFC 4034. By generating and signing these records on demand, authoritative name servers can effectively stop the disclosure of zone contents otherwise made possible by walking the chain of NSEC records in a signed zone. [STANDARDS-TRACK]
RFC4471 - Derivation of DNS Name Predecessor and Successor: This document describes two methods for deriving the canonically-ordered predecessor and successor of a DNS name. These methods may be used for dynamic NSEC resource record synthesis, enabling security-aware name servers to provide authenticated denial of existence without disclosing other owner names in a DNSSEC secured zone. This memo defines an Experimental Protocol for the Internet community.
RFC4509 - Use of SHA-256 in DNSSEC Delegation Signer (DS) Resource Records (RRs): This document specifies how to use the SHA-256 digest type in DNS Delegation Signer (DS) Resource Records (RRs). DS records, when stored in a parent zone, point to DNSKEYs in a child zone. [STANDARDS-TRACK]
RFC4592 - The Role of Wildcards in the Domain Name System: This is an update to the wildcard definition of RFC 1034. The interaction with wildcards and CNAME is changed, an error condition is removed, and the words defining some concepts central to wildcards are changed. The overall goal is not to change wildcards, but to refine the definition of RFC 1034. [STANDARDS-TRACK]
RFC4635 - HMAC SHA (Hashed Message Authentication Code, Secure Hash Algorithm) TSIG Algorithm Identifiers: Use of the Domain Name System TSIG resource record requires specification of a cryptographic message authentication code. Currently, identifiers have been specified only for HMAC MD5 (Hashed Message Authentication Code, Message Digest 5) and GSS (Generic Security Service) TSIG algorithms. This document standardizes identifiers and implementation requirements for additional HMAC SHA (Secure Hash Algorithm) TSIG algorithms and standardizes how to specify and handle the truncation of HMAC values in TSIG. [STANDARDS-TRACK]
RFC4701 - A DNS Resource Record (RR) for Encoding Dynamic Host Configuration Protocol (DHCP) Information (DHCID RR): It is possible for Dynamic Host Configuration Protocol (DHCP) clients to attempt to update the same DNS Fully Qualified Domain Name (FQDN) or to update a DNS FQDN that has been added to the DNS for another purpose as they obtain DHCP leases. Whether the DHCP server or the clients themselves perform the DNS updates, conflicts can arise. To resolve such conflicts, RFC 4703 proposes storing client identifiers in the DNS to unambiguously associate domain names with the DHCP clients to which they refer. This memo defines a distinct Resource Record (RR) type for this purpose for use by DHCP clients and servers: the "DHCID" RR. [STANDARDS-TRACK]
RFC4795 - Link-local Multicast Name Resolution (LLMNR): The goal of Link-Local Multicast Name Resolution (LLMNR) is to enable name resolution in scenarios in which conventional DNS name resolution is not possible. LLMNR supports all current and future DNS formats, types, and classes, while operating on a separate port from DNS, and with a distinct resolver cache. Since LLMNR only operates on the local link, it cannot be considered a substitute for DNS. This memo provides information for the Internet community.
RFC4955 - DNS Security (DNSSEC) Experiments: This document describes a methodology for deploying alternate, non-backwards-compatible, DNS Security (DNSSEC) methodologies in an experimental fashion without disrupting the deployment of standard DNSSEC. [STANDARDS-TRACK]
RFC4956 - DNS Security (DNSSEC) Opt-In: In the DNS security (DNSSEC) extensions, delegations to unsigned subzones are cryptographically secured. Maintaining this cryptography is not always practical or necessary. This document describes an experimental "Opt-In" model that allows administrators to omit this cryptography and manage the cost of adopting DNSSEC with large zones. This memo defines an Experimental Protocol for the Internet community.
RFC4986 - Requirements Related to DNS Security (DNSSEC) Trust Anchor Rollover: Every DNS security-aware resolver must have at least one Trust Anchor to use as the basis for validating responses from DNS signed zones. For various reasons, most DNS security-aware resolvers are expected to have several Trust Anchors. For some operations, manual monitoring and updating of Trust Anchors may be feasible, but many operations will require automated methods for updating Trust Anchors in their security-aware resolvers. This document identifies the requirements that must be met by an automated DNS Trust Anchor rollover solution for security-aware DNS resolvers. This memo provides information for the Internet community.
RFC5001 - DNS Name Server Identifier (NSID) Option: With the increased use of DNS anycast, load balancing, and other mechanisms allowing more than one DNS name server to share a single IP address, it is sometimes difficult to tell which of a pool of name servers has answered a particular query. While existing ad-hoc mechanisms allow an operator to send follow-up queries when it is necessary to debug such a configuration, the only completely reliable way to obtain the identity of the name server that responded is to have the name server include this information in the response itself. This note defines a protocol extension to support this functionality. [STANDARDS-TRACK]
RFC5011 - Automated Updates of DNS Security (DNSSEC) Trust Anchors: This document describes a means for automated, authenticated, and authorized updating of DNSSEC "trust anchors". The method provides protection against N-1 key compromises of N keys in the trust point key set. Based on the trust established by the presence of a current anchor, other anchors may be added at the same place in the hierarchy, and, ultimately, supplant the existing anchor(s).; This mechanism will require changes to resolver management behavior (but not resolver resolution behavior), and the addition of a single flag bit to the DNSKEY record. [STANDARDS-TRACK]
RFC5155 - DNS Security (DNSSEC) Hashed Authenticated Denial of Existence: The Domain Name System Security (DNSSEC) Extensions introduced the NSEC resource record (RR) for authenticated denial of existence. This document introduces an alternative resource record, NSEC3, which similarly provides authenticated denial of existence. However, it also provides measures against zone enumeration and permits gradual expansion of delegation-centric zones. [STANDARDS-TRACK]
RFC5395 - Domain Name System (DNS) IANA Considerations: Internet Assigned Number Authority (IANA) parameter assignment considerations are specified for the allocation of Domain Name System (DNS) resource record types, CLASSes, operation codes, error codes, DNS protocol message header bits, and AFSDB resource record subtypes. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.
RFC5452 - Measures for Making DNS More Resilient against Forged Answers: The current Internet climate poses serious threats to the Domain Name System. In the interim period before the DNS protocol can be secured more fully, measures can already be taken to harden the DNS to make 'spoofing' a recursing nameserver many orders of magnitude harder.; Even a cryptographically secured DNS benefits from having the ability to discard bogus responses quickly, as this potentially saves large amounts of computation.; By describing certain behavior that has previously not been standardized, this document sets out how to make the DNS more resilient against accepting incorrect responses. This document updates RFC 2181. [STANDARDS-TRACK]
RFC5625 - DNS Proxy Implementation Guidelines: This document provides guidelines for the implementation of DNS proxies, as found in broadband gateways and other similar network devices. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.
RFC5702 - Use of SHA-2 Algorithms with RSA in DNSKEY and RRSIG Resource Records for DNSSEC: This document describes how to produce RSA/SHA-256 and RSA/SHA-512 DNSKEY and RRSIG resource records for use in the Domain Name System Security Extensions (RFC 4033, RFC 4034, and RFC 4035). [STANDARDS TRACK]
RFC5933 - Use of GOST Signature Algorithms in DNSKEY and RRSIG Resource Records for DNSSEC: This document describes how to produce digital signatures and hash functions using the GOST R 34.10-2001 and GOST R 34.11-94 algorithms for DNSKEY, RRSIG, and DS resource records, for use in the Domain Name System Security Extensions (DNSSEC). [STANDARDS-TRACK]
RFC5936 - DNS Zone Transfer Protocol (AXFR): The standard means within the Domain Name System protocol for maintaining coherence among a zone's authoritative name servers consists of three mechanisms. Authoritative Transfer (AXFR) is one of the mechanisms and is defined in RFC 1034 and RFC 1035.; The definition of AXFR has proven insufficient in detail, thereby forcing implementations intended to be compliant to make assumptions, impeding interoperability. Yet today we have a satisfactory set of implementations that do interoperate. This document is a new definition of AXFR -- new in the sense that it records an accurate definition of an interoperable AXFR mechanism. [STANDARDS-TRACK]
RFC5966 - DNS Transport over TCP - Implementation Requirements: This document updates the requirements for the support of TCP as a transport protocol for DNS implementations. [STANDARDS-TRACK]
RFC6014 - Cryptographic Algorithm Identifier Allocation for DNSSEC: This document specifies how DNSSEC cryptographic algorithm identifiers in the IANA registries are allocated. It changes the requirement from "standard required" to "RFC Required". It does not change the list of algorithms that are recommended or required for DNSSEC implementations. [STANDARDS-TRACK]
RFC6195 - Domain Name System (DNS) IANA Considerations: This document specifies Internet Assigned Number Authority (IANA) parameter assignment considerations for the allocation of Domain Name System (DNS) resource record types, CLASSes, operation codes, error codes, DNS protocol message header bits, and AFSDB resource record subtypes. This memo documents an Internet Best Current Practice.
RFC6604 - xNAME RCODE and Status Bits Clarification: The Domain Name System (DNS) has long provided means, such as the CNAME (Canonical Name), whereby a DNS query can be redirected to a different name. A DNS response header has an RCODE (Response Code) field, used for indicating errors, and response status bits. This document clarifies, in the case of such redirected queries, how the RCODE and status bits correspond to the initial query cycle (where the CNAME or the like was detected) and subsequent or final query cycles. [STANDARDS-TRACK]
RFC6605 - Elliptic Curve Digital Signature Algorithm (DSA) for DNSSEC: This document describes how to specify Elliptic Curve Digital Signature Algorithm (DSA) keys and signatures in DNS Security (DNSSEC). It lists curves of different sizes and uses the SHA-2 family of hashes for signatures. [STANDARDS-TRACK]
RFC6672 - DNAME Redirection in the DNS: The DNAME record provides redirection for a subtree of the domain name tree in the DNS. That is, all names that end with a particular suffix are redirected to another part of the DNS. This document obsoletes the original specification in RFC 2672 as well as updates the document on representing IPv6 addresses in DNS (RFC 3363). [STANDARDS-TRACK]
RFC6725 - DNS Security (DNSSEC) DNSKEY Algorithm IANA Registry Updates: The DNS Security Extensions (DNSSEC) require the use of cryptographic algorithm suites for generating digital signatures over DNS data. The algorithms specified for use with DNSSEC are reflected in an IANA-maintained registry. This document presents a set of changes for some entries of the registry. [STANDARDS-TRACK]
RFC6840 - Clarifications and Implementation Notes for DNS Security (DNSSEC): This document is a collection of technical clarifications to the DNS Security (DNSSEC) document set. It is meant to serve as a resource to implementors as well as a collection of DNSSEC errata that existed at the time of writing.; This document updates the core DNSSEC documents (RFC 4033, RFC 4034, and RFC 4035) as well as the NSEC3 specification (RFC 5155). It also defines NSEC3 and SHA-2 (RFC 4509 and RFC 5702) as core parts of the DNSSEC specification.
RFC6891 - Extension Mechanisms for DNS (EDNS(0)): The Domain Name System's wire protocol includes a number of fixed fields whose range has been or soon will be exhausted and does not allow requestors to advertise their capabilities to responders. This document describes backward-compatible mechanisms for allowing the protocol to grow.; This document updates the Extension Mechanisms for DNS (EDNS(0)) specification (and obsoletes RFC 2671) based on feedback from deployment experience in several implementations. It also obsoletes RFC 2673 ("Binary Labels in the Domain Name System") and adds considerations on the use of extended labels in the DNS.
RFC6895 - Domain Name System (DNS) IANA Considerations: This document specifies Internet Assigned Numbers Authority (IANA) parameter assignment considerations for the allocation of Domain Name System (DNS) resource record types, CLASSes, operation codes, error codes, DNS protocol message header bits, and AFSDB resource record subtypes. It obsoletes RFC 6195 and updates RFCs 1183, 2845, 2930, and 3597.
RFC6944 - Applicability Statement: DNS Security (DNSSEC) DNSKEY Algorithm Implementation Status: The DNS Security Extensions (DNSSEC) requires the use of cryptographic algorithm suites for generating digital signatures over DNS data. There is currently an IANA registry for these algorithms, but there is no record of the recommended implementation status of each algorithm. This document provides an applicability statement on algorithm implementation status for DNSSEC component software. This document lists each algorithm's status based on the current reference. In the case that an algorithm is specified without an implementation status, this document assigns one. This document updates RFCs 2536, 2539, 3110, 4034, 4398, 5155, 5702, and 5933.
RFC6975 - Signaling Cryptographic Algorithm Understanding in DNS Security Extensions (DNSSEC): The DNS Security Extensions (DNSSEC) were developed to provide origin authentication and integrity protection for DNS data by using digital signatures. These digital signatures can be generated using different algorithms. This document specifies a way for validating end-system resolvers to signal to a server which digital signature and hash algorithms they support. The extensions allow the signaling of new algorithm uptake in client code to allow zone administrators to know when it is possible to complete an algorithm rollover in a DNSSEC-signed zone.