mDNS

This document specifies a method for a DNS client to request additional DNS record types to be delivered alongside the primary record type specified in the Question section of a DNS QUERY (OpCode=0).

This document describes an EDNS(0) option that can be used between DNS Update Requesters and authoritative DNS servers to include a lifetime (lease duration) in a DNS Update or DNS Update Response, allowing a server to garbage collect stale Resource Records that have been added by DNS Updates if they are not renewed.

The Service Registration Protocol (SRP) for DNS-based Service Discovery (DNS-SD) uses the standard DNS Update mechanism to enable DNS-SD using only unicast packets. This makes it possible to deploy DNS-SD without multicast, which greatly improves scalability and improves performance on networks where multicast service is not an optimal choice, particularly IEEE 802.11 (Wi-Fi) and IEEE 802.15.4 networks. DNS-SD Service registration uses public keys and SIG(0) to allow services to defend their registrations.

DNS-SD (DNS-based Service Discovery) normally discloses information about devices offering and requesting services. This information includes hostnames, network parameters, and possibly a further description of the corresponding service instance. Especially when mobile devices engage in DNS-based Service Discovery at a public hotspot, serious privacy problems arise. We analyze the requirements of a privacy-respecting discovery service.

The Domain Name System (DNS) was designed to return matching records efficiently for queries for data that are relatively static. When those records change frequently, DNS is still efficient at returning the updated results when polled, as long as the polling rate is not too high. But, there exists no mechanism for a client to be asynchronously notified when these changes occur. This document defines a mechanism for a client to be notified of such changes to DNS records, called DNS Push Notifications.

This document specifies a network proxy that uses Multicast DNS to automatically populate the wide-area unicast Domain Name System namespace with records describing devices and services found on the local link.

Despite its name, DNS-Based Service Discovery (DNS-SD) can use naming systems other than DNS when looking for services. Moreover, when it uses DNS, DNS-SD uses the full capability of DNS, rather than using a subset of available octets. This is of particular relevance where some environments use DNS labels that conform to Internationalized Domain Names for Applications (IDNA), and other environments use labels containing Unicode characters (such as containing octets corresponding to characters encoded as UTF-8). In order for DNS-SD to be used effectively in environments where multiple different name systems and conventions for their operation are in use, it is important to attend to differences in the underlying technology and operational environment. This memo presents an outline of the requirements for the selection of labels for conventional DNS and other resolution systems when they are expected to interoperate in this manner.

This memo defines a MIME content type that may be used by a Mail User Agent (MUA) or electronic mail gateway to report the disposition of a message after it has been successfully delivered to a recipient. This content type is intended to be machine processable. Additional message header fields are also defined to permit Message Disposition Notifications (MDNs) to be requested by the sender of a message. The purpose is to extend Internet Mail to support functionality often found in other messaging systems, such as X.400 and the proprietary "LAN-based" systems, and are often referred to as "read receipts," "acknowledgements," or "receipt notifications." The intention is to do this while respecting privacy concerns, which have often been expressed when such functions have been discussed in the past.

Because many messages are sent between the Internet and other messaging systems (such as X.400 or the proprietary "LAN-based" systems), the MDN protocol is designed to be useful in a multiprotocol messaging environment. To this end, the protocol described in this memo provides for the carriage of "foreign" addresses, in addition to those normally used in Internet Mail. Additional attributes may also be defined to support "tunneling" of foreign notifications through Internet Mail.

This document is an Internet Standard. It obsoletes RFC 3798 and updates RFC 2046 (message/partial media type handling) and RFC 3461 (Original-Recipient header field generation requirement).

DNS-based Service Discovery (DNS-SD) over Multicast DNS (mDNS) is widely used today for discovery and resolution of services and names on a local link, but there are use cases to extend DNS-SD/mDNS to enable service discovery beyond the local link. This document provides a problem statement and a list of requirements for scalable DNS-SD.

As networked devices become smaller, more portable, and more ubiquitous, the ability to operate with less configured infrastructure is increasingly important. In particular, the ability to look up DNS resource record data types (including, but not limited to, host names) in the absence of a conventional managed DNS server is useful.

Multicast DNS (mDNS) provides the ability to perform DNS-like operations on the local link in the absence of any conventional Unicast DNS server. In addition, Multicast DNS designates a portion of the DNS namespace to be free for local use, without the need to pay any annual fee, and without the need to set up delegations or otherwise configure a conventional DNS server to answer for those names.

The primary benefits of Multicast DNS names are that (i) they require little or no administration or configuration to set them up, (ii) they work when no infrastructure is present, and (iii) they work during infrastructure failures.

This document describes the DISCOVER opcode, an experimental extension to the Domain Name System (DNS) to use multicast queries for resource discovery. This opcode was tested in experiments run during 1995 and 1996 for the Topology Based Domain Search (TBDS) project. This project is no longer active and there are no current plans to restart it. TBDS was the first known use of multicast transport for DNS. A client multicasts a DNS query using the DISCOVER opcode and processes the multiple responses that may result. This document defines a Historic Document for the Internet community.