DNS

This document specifies an extension to the Registration Data Access Protocol (RDAP), which allows the Time-to-Live (TTL) values for relevant DNS record types to be included in RDAP responses.

This document provides guidelines and documents best current practice for operating authoritative DNS servers, recursive resolvers, and stub resolvers in a mixed IPv4/IPv6 environment. This document recommends that both authoritative DNS servers and recursive resolvers support IPv4 and IPv6. It also provides guidance on how recursive DNS resolvers should select upstream DNS servers, including when IPv4-embedded IPv6 addresses are available.

This document obsoletes RFC 3901.

This document defines an operational convention that uses the

reserved underscored DNS leaf node name "_for-sale" to indicate the

parent domain name is available for purchase.

The convention can be deployed without disrupting existing

operations, and it may be applied even when the domain name is still

actively in use.

This document defines a protocol for exchanging DNS queries (OPCODE 0) over the Constrained Application Protocol (CoAP). These CoAP messages can be protected by (D)TLS-Secured CoAP or Object Security for Constrained RESTful Environments (OSCORE) to provide encrypted DNS message exchange for constrained devices in the Internet of Things (IoT).

To use TLS Encrypted ClientHello (ECH), the client needs to learn the ECH configuration for a server before it attempts a connection to the server. This specification provides a mechanism for conveying the ECH configuration information via DNS, using a SVCB or HTTPS resource record (RR).

This document defines the Domain Name System (DNS) functionality of a Drone Remote Identification Protocol (DRIP) Identity Management Entity (DIME). It is built around DRIP Entity Tags (DETs) to standardize a hierarchical registry structure and associated processes to facilitate trustable and scalable registration and lookup of information related to Unmanned Aircraft Systems (UAS). The registry system supports issuance, discovery, and verification of DETs, enabling secure identification and association of UAS and their operators. It also defines the interactions between different classes of registries (root, organizational, and individual) and their respective roles in maintaining the integrity of the registration data. This architecture enables decentralized, federated operation while supporting privacy, traceability, and regulatory compliance requirements in the context of UAS Remote Identification and other services.

This document describes an extension to the Extensible Provisioning

Protocol (EPP) that allows EPP clients to manage the Time-to-Live

(TTL) value for domain name delegation records.

This document describes the queries that a DNS resolver should emit to initialize its cache. The result is that the resolver gets both a current NS resource record set (RRset) for the root zone and the necessary address information for reaching the root servers.

This document obsoletes RFC 8109.

The widely deployed Extension Mechanisms for DNS (EDNS(0)) feature in the DNS enables a DNS receiver to indicate its received UDP message size capacity, which supports the sending of large UDP responses by a DNS server. Large DNS/UDP messages are more likely to be fragmented, and IP fragmentation has exposed weaknesses in application protocols. It is possible to avoid IP fragmentation in DNS by limiting the response size where possible and signaling the need to upgrade from UDP to TCP transport where necessary. This document describes techniques to avoid IP fragmentation in DNS.

The DNS ZONEVERSION option is a way for DNS clients to request, and for authoritative DNS servers to provide, information regarding the version of the zone from which a response is generated. The SERIAL field from the Start of Authority (SOA) resource record (RR) is a good example of a zone's version, and it is the only one defined by this specification. Additional version types may be defined by future specifications.

Including zone version data in a response simplifies and improves the quality of debugging and diagnostics since the version and the DNS answer are provided atomically. This can be especially useful for zones and DNS providers that leverage IP anycast or multiple backend systems. It functions similarly to the DNS Name Server Identifier (NSID) option described in RFC 5001.

This document updates RFC 1035 by constraining the allowed value of the QDCOUNT parameter in DNS messages with OPCODE = 0 (QUERY) to a maximum of one, and it specifies the required behavior when values that are not allowed are encountered.

DNS error reporting is a lightweight reporting mechanism that provides the operator of an authoritative server with reports on DNS resource records that fail to resolve or validate. A domain owner or DNS hosting organization can use these reports to improve domain hosting. The reports are based on extended DNS errors as described in RFC 8914.

When a domain name fails to resolve or validate due to a misconfiguration or an attack, the operator of the authoritative server may be unaware of this. To mitigate this lack of feedback, this document describes a method for a validating resolver to automatically signal an error to a monitoring agent specified by the authoritative server. The error is encoded in the QNAME; thus, the very act of sending the query is to report the error.

The Domain Name System (DNS) is defined in literally dozens of different RFCs. The terminology used by implementers and developers of DNS protocols, and by operators of DNS systems, has changed in the decades since the DNS was first defined. This document gives current definitions for many of the terms used in the DNS in a single document.

This document updates RFC 2308 by clarifying the definitions of "forwarder" and "QNAME". It obsoletes RFC 8499 by adding multiple terms and clarifications. Comprehensive lists of changed and new definitions can be found in Appendices A and B.

This document defines a parameter that can be included in Service Binding (SVCB) and HTTPS DNS resource records to denote that a service is accessible using Oblivious HTTP, by offering an Oblivious Gateway Resource through which to access the target. This document also defines a mechanism for learning the key configuration of the discovered Oblivious Gateway Resource.

Home network owners may have devices or services hosted on their home network that they wish to access from the Internet (i.e., from a network outside of the home network). Home networks are increasingly numbered using IPv6 addresses, which in principle makes this access simpler, but accessing home networks from the Internet requires the names and IP addresses of these devices and services to be made available in the public DNS.

This document describes how a Home Naming Authority (NHA) instructs the outsourced infrastructure to publish these pieces of information in the public DNS. The names and IP addresses of the home network are set in the Public Homenet Zone by the Homenet Naming Authority (HNA), which in turn instructs an outsourced infrastructure to publish the zone on behalf of the home network owner.

This document defines DHCPv6 options so that a Homenet Naming Authority (HNA) can automatically set the appropriate configuration and outsource the authoritative naming service for the home network. In most cases, the outsourcing mechanism is transparent for the end user.

In the DNS, resolvers employ caching to reduce both latency for end users and load on authoritative name servers. The process of resolution may result in one of three types of responses: (1) a response containing the requested data, (2) a response indicating the requested data does not exist, or (3) a non-response due to a resolution failure in which the resolver does not receive any useful information regarding the data's existence. This document concerns itself only with the third type.

RFC 2308 specifies requirements for DNS negative caching. There, caching of TYPE 2 responses is mandatory and caching of TYPE 3 responses is optional. This document updates RFC 2308 to require negative caching for DNS resolution failures.

RFC 4035 allows DNSSEC validation failure caching. This document updates RFC 4035 to require caching for DNSSEC validation failures.

RFC 4697 prohibits aggressive requerying for NS records at a failed zone's parent zone. This document updates RFC 4697 to expand this requirement to all query types and to all ancestor zones.

This document provides the GNU Name System (GNS) technical specification. GNS is a decentralized and censorship-resistant domain name resolution protocol that provides a privacy-enhancing alternative to the Domain Name System (DNS) protocols.

This document defines the normative wire format of resource records, resolution processes, cryptographic routines, and security and privacy considerations for use by implementers.

This specification was developed outside the IETF and does not have IETF consensus. It is published here to inform readers about the function of GNS, guide future GNS implementations, and ensure interoperability among implementations (for example, pre-existing GNUnet implementations).

This document specifies the "SVCB" ("Service Binding") and "HTTPS" DNS resource record (RR) types to facilitate the lookup of information needed to make connections to network services, such as for HTTP origins. SVCB records allow a service to be provided from multiple alternative endpoints, each with associated parameters (such as transport protocol configuration), and are extensible to support future uses (such as keys for encrypting the TLS ClientHello). They also enable aliasing of apex domains, which is not possible with CNAME. The HTTPS RR is a variation of SVCB for use with HTTP (see RFC 9110, "HTTP Semantics"). By providing more information to the client before it attempts to establish a connection, these records offer potential benefits to both performance and privacy.

The DNS uses glue records to allow iterative clients to find the addresses of name servers that are contained within a delegated zone. Authoritative servers are expected to return all available glue records for in-domain name servers in a referral response. If message size constraints prevent the inclusion of all glue records for in-domain name servers, the server must set the TC (Truncated) flag to inform the client that the response is incomplete and that the client should use another transport to retrieve the full response. This document updates RFC 1034 to clarify correct server behavior.

This document reserves a Top-Level Domain (TLD) label "alt" to be used in non-DNS contexts. It also provides advice and guidance to developers creating alternative namespaces.

This document describes a method for automatic DNS zone provisioning among DNS primary and secondary name servers by storing and transferring the catalog of zones to be provisioned as one or more regular DNS zones.

This document deprecates the use of any "int" domain names that were designated for infrastructure purposes by the IETF, and it identifies them for removal from the "int" top-level domain. Any implementations that involve these domains are now deprecated. This document also changes the status of RFC 1528 and RFC 1706 to Historic.

This memo describes common vulnerabilities related to Domain Name System (DNS) resource record (RR) processing as seen in several DNS client implementations. These vulnerabilities may lead to successful Denial-of-Service and Remote Code Execution attacks against the affected software. Where applicable, violations of RFC 1035 are mentioned.

This document specifies a method to find which Registration Data Access Protocol (RDAP) server is authoritative to answer queries for a requested scope, such as domain names, IP addresses, or Autonomous System numbers. This document obsoletes RFC 7484.

This document describes the changes between Unicode 6.0.0 and Unicode 12.0.0 in the context of the current version of Internationalized Domain Names for Applications 2008 (IDNA2008). Some additions and changes have been made in the Unicode Standard that affect the values produced by the algorithm IDNA2008 specifies. IDNA2008 allows adding exceptions to the algorithm for backward compatibility; however, this document does not add any such exceptions. This document provides the necessary tables to IANA to make its database consistent with Unicode 12.0.0.

To improve understanding, this document describes systems that are being used as alternatives to those that conform to IDNA2008.

This document updates RFCs 1123 and 1536. This document requires the operational practice of permitting DNS messages to be carried over TCP on the Internet as a Best Current Practice. This operational requirement is aligned with the implementation requirements in RFC 7766. The use of TCP includes both DNS over unencrypted TCP as well as over an encrypted TLS session. The document also considers the consequences of this form of DNS communication and the potential operational issues that can arise when this Best Current Practice is not upheld.

Recent research work has explored the deployment characteristics and configuration of the Domain Name System (DNS). This document summarizes the conclusions from these research efforts and offers specific, tangible considerations or advice to authoritative DNS server operators. Authoritative server operators may wish to follow these considerations to improve their DNS services.

It is possible that the results presented in this document could be applicable in a wider context than just the DNS protocol, as some of the results may generically apply to any stateless/short-duration anycasted service.

This document is not an IETF consensus document: it is published for informational purposes.

This document describes a technique called "QNAME minimisation" to improve DNS privacy, where the DNS resolver no longer always sends the full original QNAME and original QTYPE to the upstream name server. This document obsoletes RFC 7816.

This document describes revisions to operational practices to separate the function of the "arpa" top-level domain in the DNS from its historical operation alongside the DNS root zone.

This document introduces the YANG module "iana-dns-class-rr-type", which contains derived types reflecting two IANA registries: DNS CLASSes and Resource Record (RR) TYPEs. These YANG types are intended as the minimum basis for future data modeling work.

This document describes an extension of Extensible Provisioning Protocol (EPP) domain name mapping for the provisioning and management of strict bundling registration of domain names. Specified in XML, this mapping extends the EPP domain name mapping to provide additional features required for the provisioning of bundled domain names. This is a nonstandard proprietary extension.

This document specifies the format, contents, and semantics of Domain Name Registration Data (DNRD) escrow deposits for a domain name registry.

DNS Cookies, as specified in RFC 7873, are a lightweight DNS transaction security mechanism that provide limited protection to DNS servers and clients against a variety of denial-of-service amplification, forgery, or cache-poisoning attacks by off-path attackers.

This document updates RFC 7873 with precise directions for creating Server Cookies so that an anycast server set including diverse implementations will interoperate with standard clients, with suggestions for constructing Client Cookies in a privacy-preserving fashion, and with suggestions on how to update a Server Secret. An IANA registry listing the methods and associated pseudorandom function suitable for creating DNS Server Cookies has been created with the method described in this document as the first and, as of the time of publication, only entry.

This document describes a protocol for transaction-level authentication using shared secrets and one-way hashing. It can be used to authenticate dynamic updates to a DNS zone as coming from an approved client or to authenticate responses as coming from an approved name server.

No recommendation is made here for distributing the shared secrets; it is expected that a network administrator will statically configure name servers and clients using some out-of-band mechanism.

This document obsoletes RFCs 2845 and 4635.

This document defines an extensible method to return additional information about the cause of DNS errors. Though created primarily to extend SERVFAIL to provide additional information about the cause of DNS and DNSSEC failures, the Extended DNS Errors option defined in this document allows all response types to contain extended error information. Extended DNS Error information does not change the processing of RCODEs.

The DNS is a query/response protocol. Failing to respond to queries, or responding incorrectly, causes both immediate operational problems and long-term problems with protocol development.

This document identifies a number of common kinds of queries to which some servers either fail to respond or respond incorrectly. This document also suggests procedures for zone operators to apply to identify and remediate the problem.

The document does not look at the DNS data itself, just the structure of the responses.

This document describes an email authentication method compliant with RFC 8601. The method consists of looking up the sender's IP address in a DNS whitelist. This document provides information in case the method is seen in the field, suggests a useful practice, and registers the relevant keywords.

This document does not consider blacklists.

Provisioning Domains (PvDs) are defined as consistent sets of network configuration information. PvDs allows hosts to manage connections to multiple networks and interfaces simultaneously, such as when a home router provides connectivity through both a broadband and cellular network provider.

This document defines a mechanism for explicitly identifying PvDs through a Router Advertisement (RA) option. This RA option announces a PvD identifier, which hosts can compare to differentiate between PvDs. The option can directly carry some information about a PvD and can optionally point to PvD Additional Information that can be retrieved using HTTP over TLS.

Apple's DNS Long-Lived Queries (LLQ) is a mechanism for extending the DNS protocol to support change notification, thus allowing clients to learn about changes to DNS data without polling the server. From 2005 onwards, LLQ was implemented in Apple products including Mac OS X, Bonjour for Windows, and AirPort wireless base stations. In 2020, the LLQ protocol was superseded by the IETF Standards Track RFC 8765, "DNS Push Notifications", which builds on experience gained with the LLQ protocol to create a superior replacement.

The existing LLQ protocol deployed and used from 2005 to 2020 is documented here to give background regarding the operational experience that informed the development of DNS Push Notifications, and to help facilitate a smooth transition from LLQ to DNS Push Notifications.

Some DNS recursive resolvers have longer-than-desired round-trip times to the closest DNS root server; those resolvers may have difficulty getting responses from the root servers, such as during a network attack. Some DNS recursive resolver operators want to prevent snooping by third parties of requests sent to DNS root servers. In both cases, resolvers can greatly decrease the round-trip time and prevent observation of requests by serving a copy of the full root zone on the same server, such as on a loopback address or in the resolver software. This document shows how to start and maintain such a copy of the root zone that does not cause problems for other users of the DNS, at the cost of adding some operational fragility for the operator.

This document obsoletes RFC 7706.

This document updates RFC 7450, "Automatic Multicast Tunneling" (or AMT), by modifying the relay discovery process. A new DNS resource record named AMTRELAY is defined for publishing AMT relays for source-specific multicast channels. The reverse IP DNS zone for a multicast sender's IP address is configured to use AMTRELAY resource records to advertise a set of AMT relays that can receive and forward multicast traffic from that sender over an AMT tunnel. Other extensions and clarifications to the relay discovery process are also defined.

The standards for Internationalized Domain Names in Applications (IDNA) require a review of each new version of Unicode to determine whether incompatibilities with prior versions or other issues exist and, where appropriate, to allow the IETF to decide on the trade-offs between compatibility with prior IDNA versions and compatibility with Unicode going forward. That requirement, and its relationship to tables maintained by IANA, has caused significant confusion in the past. This document makes adjustments to the review procedure based on experience and updates IDNA, specifically RFC 5892, to reflect those changes and to clarify the various relationships involved. It also makes other minor adjustments to align that document with experience.

This document defines a method (serve-stale) for recursive resolvers to use stale DNS data to avoid outages when authoritative nameservers cannot be reached to refresh expired data. One of the motivations for serve-stale is to make the DNS more resilient to DoS attacks and thereby make them less attractive as an attack vector. This document updates the definitions of TTL from RFCs 1034 and 1035 so that data can be kept in the cache beyond the TTL expiry; it also updates RFC 2181 by interpreting values with the high-order bit set as being positive, rather than 0, and suggests a cap of 7 days.

The Certification Authority Authorization (CAA) DNS Resource Record allows a DNS domain name holder to specify one or more Certification Authorities (CAs) authorized to issue certificates for that domain name. CAA Resource Records allow a public CA to implement additional controls to reduce the risk of unintended certificate mis-issue. This document defines the syntax of the CAA record and rules for processing CAA records by CAs.

This document obsoletes RFC 6844.

This document describes a data representation for collections of DNS messages. The format is designed for efficient storage and transmission of large packet captures of DNS traffic; it attempts to minimize the size of such packet capture files but retain the full DNS message contents along with the most useful transport metadata. It is intended to assist with the development of DNS traffic- monitoring applications.

This document defines two Configuration Payload Attribute Types (INTERNAL_DNS_DOMAIN and INTERNAL_DNSSEC_TA) for the Internet Key Exchange Protocol version 2 (IKEv2). These payloads add support for private (internal-only) DNS domains. These domains are intended to be resolved using non-public DNS servers that are only reachable through the IPsec connection. DNS resolution for other domains remains unchanged. These Configuration Payloads only apply to split- tunnel configurations.

Formally, any DNS Resource Record (RR) may occur under any domain name. However, some services use an operational convention for defining specific interpretations of an RRset by locating the records in a DNS branch under the parent domain to which the RRset actually applies. The top of this subordinate branch is defined by a naming convention that uses a reserved node name, which begins with the underscore character (e.g., "_name"). The underscored naming construct defines a semantic scope for DNS record types that are associated with the parent domain above the underscored branch. This specification explores the nature of this DNS usage and defines the "Underscored and Globally Scoped DNS Node Names" registry with IANA. The purpose of this registry is to avoid collisions resulting from the use of the same underscored name for different services.

Using an underscore for a prefix creates a space for constrained interoperation of resource records. Original uses of an underscore character as a domain node name prefix were specified without the benefit of an IANA registry. This produced an entirely uncoordinated set of name-creation activities, all drawing from the same namespace. A registry for these names has now been defined by RFC 8552. However, the existing specifications that use underscored naming need to be modified in order to be in line with the new registry. This document specifies those changes. The changes preserve existing software and operational practice, while adapting the specifications for those practices to the newer underscore registry model.

This document defines a new DNS OPCODE for DNS Stateful Operations (DSO). DSO messages communicate operations within persistent stateful sessions using Type Length Value (TLV) syntax. Three TLVs are defined that manage session timeouts, termination, and encryption padding, and a framework is defined for extensions to enable new stateful operations. This document updates RFC 1035 by adding a new DNS header OPCODE that has both different message semantics and a new result code. This document updates RFC 7766 by redefining a session, providing new guidance on connection reuse, and providing a new mechanism for handling session idle timeouts.

The Domain Name System (DNS) specifies a query type (QTYPE) "ANY". The operator of an authoritative DNS server might choose not to respond to such queries for reasons of local policy, motivated by security, performance, or other reasons.

The DNS specification does not include specific guidance for the behavior of DNS servers or clients in this situation. This document aims to provide such guidance.

This document updates RFCs 1034 and 1035.

In IPv4, Internet Service Providers (ISPs) commonly provide IN-ADDR.ARPA information for their customers by prepopulating the zone with one PTR record for every available address. This practice does not scale in IPv6. This document analyzes different approaches and considerations for ISPs in managing the IP6.ARPA zone.

Some applications use DNS messages, or parts of DNS messages, as data. For example, a system that captures DNS queries and responses might want to be able to easily search them without having to decode the messages each time. Another example is a system that puts together DNS queries and responses from message parts. This document describes a general format for DNS message data in JSON. Specific profiles of the format in this document can be described in other documents for specific applications and usage scenarios.

This document describes an Extensible Provisioning Protocol (EPP) extension mapping for the provisioning and management of domain name registrations and applications during the launch of a domain name registry.

The basic design of the Domain Name System was completed almost 30 years ago. The last half of that period has been characterized by significant changes in requirements and expectations, some of which either require changes to how the DNS is used or can be accommodated only poorly or not at all. This document asks the question of whether it is time to either redesign and replace the DNS to match contemporary requirements and expectations (rather than continuing to try to design and implement incremental patches that are not fully satisfactory) or draw some clear lines about functionality that is not really needed or that should be performed in some other way.

Many communication protocols operating over the modern Internet use hostnames. These often resolve to multiple IP addresses, each of which may have different performance and connectivity characteristics. Since specific addresses or address families (IPv4 or IPv6) may be blocked, broken, or sub-optimal on a network, clients that attempt multiple connections in parallel have a chance of establishing a connection more quickly. This document specifies requirements for algorithms that reduce this user-visible delay and provides an example algorithm, referred to as "Happy Eyeballs". This document obsoletes the original algorithm description in RFC 6555.

This document specifies IPv6 Router Advertisement (RA) options (called "DNS RA options") to allow IPv6 routers to advertise a list of DNS Recursive Server Addresses and a DNS Search List to IPv6 hosts.

This document, which obsoletes RFC 6106, defines a higher default value of the lifetime of the DNS RA options to reduce the likelihood of expiry of the options on links with a relatively high rate of packet loss.

This document states clearly that when a DNS resolver receives a response with a response code of NXDOMAIN, it means that the domain name which is thus denied AND ALL THE NAMES UNDER IT do not exist.

This document clarifies RFC 1034 and modifies a portion of RFC 2308: it updates both of them.

This document specifies a resource record (RR) for the Domain Name System (DNS) and how to use it with the Host Identity Protocol (HIP). This RR allows a HIP node to store in the DNS its Host Identity (HI), the public component of the node public-private key pair; its Host Identity Tag (HIT), a truncated hash of its public key (PK); and the domain names of its rendezvous servers (RVSs). This document obsoletes RFC 5205.

The Request Routing interface comprises (1) the asynchronous advertisement of footprint and capabilities by a downstream Content Delivery Network (CDN) that allows an upstream CDN to decide whether to redirect particular user requests to that downstream CDN; and (2) the synchronous operation of an upstream CDN requesting whether a downstream CDN is prepared to accept a user request and of a downstream CDN responding with how to actually redirect the user request. This document describes an interface for the latter part, i.e., the CDNI Request Routing Redirection interface.

RFC 3263 defines how a Session Initiation Protocol (SIP) implementation, given a SIP Uniform Resource Identifier (URI), should locate the next-hop SIP server using Domain Name System (DNS) procedures. As SIP networks increasingly transition from IPv4-only to dual-stack, a quality user experience must be ensured for dual- stack SIP implementations. This document updates the DNS procedures described in RFC 3263 for dual-stack SIP implementations in preparation for forthcoming specifications for applying "Happy Eyeballs" principles to SIP.

DNS Cookies are a lightweight DNS transaction security mechanism that provides limited protection to DNS servers and clients against a variety of increasingly common denial-of-service and amplification/ forgery or cache poisoning attacks by off-path attackers. DNS Cookies are tolerant of NAT, NAT-PT (Network Address Translation - Protocol Translation), and anycast and can be incrementally deployed. (Since DNS Cookies are only returned to the IP address from which they were originally received, they cannot be used to generally track Internet users.)

RFC 6598 specifies that "Reverse DNS queries for Shared Address Space addresses [100.64.0.0/10] MUST NOT be forwarded to the global DNS infrastructure."

This document formally directs IANA to add the associated zones to the "IPv4 Locally-Served DNS Zones Registry" to prevent such queries from accidentally leaking to the global DNS infrastructure.

The Internet is structured to be an open communications medium. This openness is one of the key underpinnings of Internet innovation, but it can also allow communications that may be viewed as undesirable by certain parties. Thus, as the Internet has grown, so have mechanisms to limit the extent and impact of abusive or objectionable communications. Recently, there has been an increasing emphasis on "blocking" and "filtering", the active prevention of such communications. This document examines several technical approaches to Internet blocking and filtering in terms of their alignment with the overall Internet architecture. When it is possible to do so, the approach to blocking and filtering that is most coherent with the Internet architecture is to inform endpoints about potentially undesirable services, so that the communicants can avoid engaging in abusive or objectionable communications. We observe that certain filtering and blocking approaches can cause unintended consequences to third parties, and we discuss the limits of efficacy of various approaches.

This document specifies the requirement for support of TCP as a transport protocol for DNS implementations and provides guidelines towards DNS-over-TCP performance on par with that of DNS-over-UDP. This document obsoletes RFC 5966 and therefore updates RFC 1035 and RFC 1123.

This document defines an Extensible Markup Language (XML) schema for reverse DNS management in a tightly controlled Representational State Transfer (REST) environment. This document describes a schema that has been developed and deployed by ICANN in a "RESTful" system since 2011 and is being used by the registries responsible for reverse DNS (rDNS) delegations underneath IN-ADDR.ARPA and IP6.ARPA through an HTTPS transaction that is mediated by an X.509 certificate.

The DNS root name service is a critical part of the Internet architecture. The protocol and deployment requirements for the DNS root name service are defined in this document. Operational requirements are out of scope.

This document improves the security of the Extensible Messaging and Presence Protocol (XMPP) in two ways. First, it specifies how to establish a strong association between a domain name and an XML stream, using the concept of "prooftypes". Second, it describes how to securely delegate a service domain name (e.g., example.com) to a target server hostname (e.g., hosting.example.net); this is especially important in multi-tenanted environments where the same target server hosts a large number of domains.

This document specifies a means to find authoritative RADIUS servers for a given realm. It is used in conjunction with either RADIUS over Transport Layer Security (RADIUS/TLS) or RADIUS over Datagram Transport Layer Security (RADIUS/DTLS).

Internet mail determines the address of a receiving server through the DNS, first by looking for an MX record and then by looking for an A/AAAA record as a fallback. Unfortunately, this means that the A/AAAA record is taken to be mail server address even when that address does not accept mail. The No Service MX RR, informally called "null MX", formalizes the existing mechanism by which a domain announces that it accepts no mail, without having to provide a mail server; this permits significant operational efficiencies.

This document describes the already registered DNS resource record (RR) type, called the Uniform Resource Identifier (URI) RR, that is used for publishing mappings from hostnames to URIs.

Many sites connected to the Internet make use of IPv4 addresses that are not globally unique. Examples are the addresses designated in RFC 1918 for private use within individual sites.

Devices in such environments may occasionally originate Domain Name System (DNS) queries (so-called "reverse lookups") corresponding to those private-use addresses. Since the addresses concerned have only local significance, it is good practice for site administrators to ensure that such queries are answered locally. However, it is not uncommon for such queries to follow the normal delegation path in the public DNS instead of being answered within the site.

It is not possible for public DNS servers to give useful answers to such queries. In addition, due to the wide deployment of private-use addresses and the continuing growth of the Internet, the volume of such queries is large and growing. The AS112 project aims to provide a distributed sink for such queries in order to reduce the load on the corresponding authoritative servers. The AS112 project is named after the Autonomous System Number (ASN) that was assigned to it.

This document describes the steps required to install a new AS112 node and offers advice relating to such a node's operation.

This document obsoletes RFC 6304.

AS112 provides a mechanism for handling reverse lookups on IP addresses that are not unique (e.g., RFC 1918 addresses). This document describes modifications to the deployment and use of AS112 infrastructure that will allow zones to be added and dropped much more easily, using DNAME resource records.

This approach makes it possible for any DNS zone administrator to sink traffic relating to parts of the global DNS namespace under their control to the AS112 infrastructure without coordination with the operators of AS112 infrastructure.

This document specifies how a child zone in the DNS can publish a

record to indicate to a parental agent that the parental agent may

copy and process certain records from the child zone. The existence

of the record and any change in its value can be monitored by a

parental agent and acted on depending on local policy.

The Ed25519 signature algorithm has been implemented in OpenSSH. This document updates the IANA "SSHFP RR Types for public key algorithms" registry by adding an algorithm number for Ed25519.

This document focuses on the problems encountered when using dynamic DNS in address-sharing contexts (e.g., Dual-Stack Lite (DS-Lite) and Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers (NAT64)) during IPv6 transition. Both issues and possible solutions are documented in this memo.

This document outlines a possible, but not recommended, method to mitigate the effect of collisions in the DNS namespace by providing a means for end users to disambiguate the conflict.

The residential gateway is a device that has become an integral part of home networking equipment. Discovering a Location Information Server (LIS) is a necessary part of acquiring location information for location-based services. However, discovering a LIS when a residential gateway is present poses a configuration challenge, requiring a method that is able to work around the obstacle presented by the gateway.

This document describes a solution to this problem. The solution provides alternative domain names as input to the LIS discovery process based on the network addresses assigned to a Device.

Recent statements from the Internet Architecture Board (IAB) and the Internet Corporation of Assigned Names and Numbers (ICANN) Security and Stability Advisory Committee have focused on the problems that the DNS is likely to experience with top-level domains (TLDs) that contain address records (so-called "dotless domains"). In order to help researchers determine the extent of the issues with dotless domains, this document lists the current dotless TLDs and gives a script for finding them. This document lists data about dotless TLDs but does not address the policy and technology issues other than to point to the statements of others.

48-bit Extended Unique Identifier (EUI-48) and 64-bit Extended Unique Identifier (EUI-64) are address formats specified by the IEEE for use in various layer-2 networks, e.g., Ethernet.

This document describes two new DNS resource record types, EUI48 and EUI64, for encoding Ethernet addresses in the DNS.

This document describes potentially severe privacy implications resulting from indiscriminate publication of link-layer addresses in the DNS. EUI-48 or EUI-64 addresses SHOULD NOT be published in the public DNS. This document specifies an interoperable encoding of these address types for use in private DNS namespaces, where the privacy concerns can be constrained and mitigated.

A number of Internet applications rely on the Domain Name System (DNS) to support their operations. Many applications use the DNS to locate services for a domain; some, for example, transform identifiers other than domain names into formats that the DNS can process, and then fetch application data or service location data from the DNS. Proposals incorporating sophisticated application behavior using DNS as a substrate have raised questions about the role of the DNS as an application platform. This document explores the architectural consequences of using the DNS to implement certain application features, and it provides guidance to future application designers as to the limitations of the DNS as a substrate and the situations in which alternative designs should be considered.

Internationalized Domain Names for Applications (IDNA) provides a method to map a subset of names written in Unicode into the DNS. Because of Unicode decisions, appearance, language and writing system conventions, and historical reasons, it often has been asserted that there is more than one way to write what competent readers and writers think of as the same host name; these different ways of writing are often called "variants". (The authors note that there are many conflicting definitions for the term "variant" in the IDNA community.) This document surveys the approaches that top-level domains have taken to the registration and provisioning of domain names that have variants. This document is not a product of the IETF, does not propose any method to make variants work "correctly", and is not an introduction to internationalization or IDNA.

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.

Internationalized Domain Names in Applications (IDNA) makes available to DNS zone administrators a very wide range of Unicode code points. Most operators of zones should probably not permit registration of U-labels using the entire range. This is especially true of zones that accept registrations across organizational boundaries, such as top-level domains and, most importantly, the root. It is unfortunately not possible to generate algorithms to determine whether permitting a code point presents a low risk. This memo presents a set of principles that can be used to guide the decision of whether a Unicode code point may be wisely included in the repertoire of permissible code points in a U-label in a zone.

A multi-interfaced node is connected to multiple networks, some of which might be utilizing private DNS namespaces. A node commonly receives recursive DNS server configuration information from all connected networks. Some of the recursive DNS servers might have information about namespaces other servers do not have. When a multi-interfaced node needs to utilize DNS, the node has to choose which of the recursive DNS servers to use. This document describes DHCPv4 and DHCPv6 options that can be used to configure nodes with information required to perform informed recursive DNS server selection decisions. [STANDARDS-TRACK]

This note describes additional optional resource records for use with the Domain Name System (DNS). These optional resource records are for use with the Identifier-Locator Network Protocol (ILNP). This document is a product of the IRTF Routing Research Group. This document defines an Experimental Protocol for the Internet community.

The NFS version 4 (NFSv4) protocol provides a mechanism for a collection of NFS file servers to collaborate in providing an organization-wide file namespace. The DNS SRV Resource Record (RR) allows a simple way for an organization to publish the root of its file system namespace, even to clients that might not be intimately associated with such an organization. The DNS SRV RR can be used to join these organization-wide file namespaces together to allow construction of a global, uniform NFS file namespace. [STANDARDS-TRACK]

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]

This document updates the IANA registries in RFC 4255, which defines SSHFP, a DNS Resource Record (RR) that contains a standard Secure Shell (SSH) key fingerprint used to verify SSH host keys using DNS Security Extensions (DNSSEC). This document defines additional options supporting SSH public keys applying the Elliptic Curve Digital Signature Algorithm (ECDSA) and the implementation of fingerprints computed using the SHA-256 message digest algorithm in SSHFP Resource Records. [STANDARDS-TRACK]

Bump-in-the-Host (BIH) is a host-based IPv4 to IPv6 protocol translation mechanism that allows a class of IPv4-only applications that work through NATs to communicate with IPv6-only peers. The host on which applications are running may be connected to IPv6-only or dual-stack access networks. BIH hides IPv6 and makes the IPv4-only applications think they are talking with IPv4 peers by local synthesis of IPv4 addresses. This document obsoletes RFC 2767 and RFC 3338. [STANDARDS-TRACK]

The rise of spam and other anti-social behavior on the Internet has led to the creation of shared DNS-based lists (DNSBLs) of IP addresses or domain names intended to help guide email filtering. This memo summarizes guidelines of accepted best practice for the management of public DNSBLs by their operators as well as for the proper use of such lists by mail server administrators (DNSBL users), and it provides useful background for both parties. It is not intended to advise on the utility or efficacy of particular DNSBLs or the DNSBL concept in general, nor to assist end users with questions about spam. This document is not an Internet Standards Track specification; it is published for informational purposes.

In order to derive a Domain-Specific Root Key (DSRK) from the Extended Master Session Key (EMSK) generated as a side effect of an Extensible Authentication Protocol (EAP) method, the EAP peer must discover the name of the domain to which it is attached.

This document specifies a Dynamic Host Configuration Protocol Version 6 (DHCPv6) option designed to allow a DHCPv6 server to inform clients using the EAP Re-authentication Protocol (ERP) EAP method of the name of the local domain for ERP. [STANDARDS-TRACK]

This document describes issues encountered by a node attached to multiple provisioning domains. This node receives configuration information from each of its provisioning domains, where some configuration objects are global to the node and others are local to the interface. Issues such as selecting the wrong interface to send traffic happen when conflicting node-scoped configuration objects are received and inappropriately used. Moreover, other issues are the result of simultaneous attachment to multiple networks, such as domain selection or addressing and naming space overlaps, regardless of the provisioning mechanism. While multiple provisioning domains are typically seen on nodes with multiple interfaces, this document also discusses situations involving single-interface nodes. This document is not an Internet Standards Track specification; it is published for informational purposes.

This memo documents IETF consensus for Internationalized Domain Names for Applications (IDNA) derived character properties related to the three code points, existing in Unicode 5.2, that changed property values when version 6.0 was released. The consensus is that no update is needed to RFC 5892 based on the changes made in Unicode 6.0. [STANDARDS-TRACK]

This document makes recommendations regarding the use of unique origin autonomous system numbers (ASNs) per node for globally anycasted critical infrastructure services in order to provide routing system discriminators for a given anycasted prefix. Network management and monitoring techniques, or other operational mechanisms, may employ this new discriminator in whatever manner best accommodates their operating environment. This memo documents an Internet Best Current Practice.

Experience with the Domain Name System (DNS) has shown that there are a number of DNS zones that all iterative resolvers and recursive nameservers should automatically serve, unless configured otherwise. RFC 4193 specifies that this should occur for D.F.IP6.ARPA. This document extends the practice to cover the IN-ADDR.ARPA zones for RFC 1918 address space and other well-known zones with similar characteristics. This memo documents an Internet Best Current Practice.

Many sites connected to the Internet make use of IPv4 addresses that are not globally unique. Examples are the addresses designated in RFC 1918 for private use within individual sites.

Hosts should never normally send DNS reverse-mapping queries for those addresses on the public Internet. However, such queries are frequently observed. Authoritative servers are deployed to provide authoritative answers to such queries as part of a loosely coordinated effort known as the AS112 project.

Since queries sent to AS112 servers are usually not intentional, the replies received back from those servers are typically unexpected. Unexpected inbound traffic can trigger alarms on intrusion detection systems and firewalls, and operators of such systems often mistakenly believe that they are being attacked.

This document provides background information and technical advice to those firewall operators. This document is not an Internet Standards Track specification; it is published for informational purposes.

Management of name servers for the Domain Name System (DNS) has traditionally been done using vendor-specific monitoring, configuration, and control methods. Although some service monitoring platforms can test the functionality of the DNS itself, there is not an interoperable way to manage (monitor, control, and configure) the internal aspects of a name server itself.

This document discusses the requirements of a management system for name servers and can be used as a shopping list of needed features for such a system. This document is not an Internet Standards Track specification; it is published for informational purposes.

This specification describes how SRV records can be used to locate email services. [STANDARDS-TRACK]

This document discusses the use of the Domain Name System (DNS) for storage of data associated with E.164 numbers, and for resolving those numbers into URIs that can be used (for example) in telephony call setup. This document also describes how the DNS can be used to identify the services associated with an E.164 number. This document obsoletes RFC 3761. [STANDARDS-TRACK]

This document specifies a revision of the IANA Registration Guidelines for Enumservices, describes corresponding registration procedures, and provides a guideline for creating Enumservice Specifications. [STANDARDS-TRACK]

This document revises all Enumservices that were IANA registered under the now obsolete specification of the Enumservice registry defined in RFC 3761. [STANDARDS-TRACK]

This document explores issues with Internationalized Domain Names (IDNs) that result from the use of various encoding schemes such as UTF-8 and the ASCII-Compatible Encoding produced by the Punycode algorithm. It focuses on the importance of agreeing on a single encoding and how complicated the state of affairs ends up being as a result of using different encodings today.

Large Proxy Mobile IPv6 deployments would benefit from a functionality where a Mobile Access Gateway could dynamically discover a Local Mobility Anchor for a Mobile Node attaching to a Proxy Mobile IPv6 domain. The purpose of the dynamic discovery functionality is to reduce the amount of static configuration in the Mobile Access Gateway. This document describes several possible dynamic Local Mobility Anchor discovery solutions. This document is not an Internet Standards Track specification; it is published for informational purposes.

This document is a guideline for registries and registrars on registering internationalized domain names (IDNs) based on (in alphabetical order) Bosnian, Bulgarian, Byelorussian, Kildin Sami, Macedonian, Montenegrin, Russian, Serbian, and Ukrainian languages in a DNS zone. It describes appropriate characters for registration and variant considerations for characters from Greek and Latin scripts with similar appearances and/or derivations. This document is not an Internet Standards Track specification; it is published for informational purposes.

In the original version of the Internationalized Domain Names in Applications (IDNA) protocol, any Unicode code points taken from user input were mapped into a set of Unicode code points that "made sense", and then encoded and passed to the domain name system (DNS). The IDNA2008 protocol (described in RFCs 5890, 5891, 5892, and 5893) presumes that the input to the protocol comes from a set of "permitted" code points, which it then encodes and passes to the DNS, but does not specify what to do with the result of user input. This document describes the actions that can be taken by an implementation between receiving user input and passing permitted code points to the new IDNA protocol. This document is not an Internet Standards Track specification; it is published for informational purposes.

This document is one of a collection that, together, describe the protocol and usage context for a revision of Internationalized Domain Names for Applications (IDNA), superseding the earlier version. It describes the document collection and provides definitions and other material that are common to the set. [STANDARDS-TRACK]

This document is the revised protocol definition for Internationalized Domain Names (IDNs). The rationale for changes, the relationship to the older specification, and important terminology are provided in other documents. This document specifies the protocol mechanism, called Internationalized Domain Names in Applications (IDNA), for registering and looking up IDNs in a way that does not require changes to the DNS itself. IDNA is only meant for processing domain names, not free text. [STANDARDS-TRACK]

This document specifies rules for deciding whether a code point, considered in isolation or in context, is a candidate for inclusion in an Internationalized Domain Name (IDN).

It is part of the specification of Internationalizing Domain Names in Applications 2008 (IDNA2008). [STANDARDS-TRACK]

The use of right-to-left scripts in Internationalized Domain Names (IDNs) has presented several challenges. This memo provides a new Bidi rule for Internationalized Domain Names for Applications (IDNA) labels, based on the encountered problems with some scripts and some shortcomings in the 2003 IDNA Bidi criterion. [STANDARDS-TRACK]

Several years have passed since the original protocol for Internationalized Domain Names (IDNs) was completed and deployed. During that time, a number of issues have arisen, including the need to update the system to deal with newer versions of Unicode. Some of these issues require tuning of the existing protocols and the tables on which they depend. This document provides an overview of a revised system and provides explanatory material for its components. This document is not an Internet Standards Track specification; it is published for informational purposes.

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]

This document specifies a stable naming scheme for the nameservers that serve the zones IN-ADDR.ARPA and IP6.ARPA in the DNS. These zones contain data that facilitate reverse mapping (address to name). This memo documents an Internet Best Current Practice.

This document specifies how to use DNS (Domain Name Service) SRV RRs (Resource Records) to locate services for the AFS distributed file system and how the priority and weight values of the SRV RR should be interpreted in the server ranking system used by AFS. It updates RFC 1183 to deprecate the use of the AFSDB RR to locate AFS cell database servers and provides guidance for backward compatibility. [STANDARDS TRACK]

The rise of spam and other anti-social behavior on the Internet has led to the creation of shared blacklists and whitelists of IP addresses or domains. The DNS has become the de-facto standard method of distributing these blacklists and whitelists. This memo documents the structure and usage of DNS-based blacklists and whitelists, and the protocol used to query them. This document is not an Internet Standards Track specification; it is published for informational purposes.

This document constitutes technical specifications for the use of Arabic in Internet domain names and provides linguistic guidelines for Arabic domain names. It addresses Arabic-specific linguistic issues pertaining to the use of Arabic language in domain names. This document is not an Internet Standards Track specification; it is published for informational purposes.

This document defines application service tags that allow service location without relying on rigid domain naming conventions, and DNS procedures for discovering servers that provide IEEE 802.21-defined Mobility Services. Such Mobility Services are used to assist a Mobile Node (MN) supporting IEEE 802.21, in handover preparation (network discovery) and handover decision (network selection). The services addressed by this document are the Media Independent Handover Services defined in IEEE 802.21. [STANDARDS-TRACK]

This document describes an Extensible Provisioning Protocol (EPP) mapping for the provisioning and management of Internet domain names stored in a shared central repository. Specified in XML, the mapping defines EPP command syntax and semantics as applied to domain names. This document obsoletes RFC 4931. [STANDARDS-TRACK]

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.

This note discusses how to extend the DNS with new data for a new application. DNS extension discussions too often focus on reuse of the TXT Resource Record Type. This document lists different mechanisms to extend the DNS, and concludes that the use of a new DNS Resource Record Type is the best solution. This memo provides information for the Internet community.

This document defines the use case for Infrastructure ENUM and proposes its implementation as a parallel namespace to "e164.arpa", as defined in RFC 3761, as the long-term solution to the problem of allowing carriers to provision DNS records for telephone numbers independently of those provisioned by end users (number assignees). This memo provides information for the Internet community.

This document registers with IANA two new DNS SRV protocol labels for resolving Instant Messaging and Presence services with SIP. [STANDARDS TRACK]

This document captures experiences in implementing systems based on the ENUM protocol and experiences of ENUM data that have been created by others. As such, it clarifies the ENUM and Dynamic Delegation Discovery System standards. Its aim is to help others by reporting both what is "out there" and potential pitfalls in interpreting the set of documents that specify the ENUM protocol. It does not revise the standards but is intended to provide technical input to future revisions of those documents. This memo provides information for the Internet community.

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]

This document describes ways to prevent the use of default configured recursive nameservers as reflectors in Denial of Service (DoS) attacks. It provides recommended configuration as measures to mitigate the attack. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.

This document describes experiences of operational requirements and several considerations for ENUM-based softswitches concerning call routing between two Korean Voice over IP (VoIP) carriers, gained during the ENUM pre-commercial trial hosted by the National Internet Development Agency of Korea (NIDA) in 2006.

These experiences show that an interim solution can maintain the stability of ongoing commercial softswitch system operations during the initial stage of ENUM service, where the DNS does not have sufficient data for the majority of calls. This memo provides information for the Internet community.