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Hybrid Unicast/Multicast DNS-Based Service Discovery

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 8766.
Expired & archived
Author Stuart Cheshire
Last updated 2016-08-07 (Latest revision 2016-02-04)
Replaces draft-cheshire-dnssd-hybrid
RFC stream Internet Engineering Task Force (IETF)
Additional resources Mailing list discussion
Stream WG state WG Document
Document shepherd (None)
IESG IESG state Expired
Consensus boilerplate Unknown
Telechat date (None)
Responsible AD (None)
Send notices to (None)

This Internet-Draft is no longer active. A copy of the expired Internet-Draft is available in these formats:


Performing DNS-Based Service Discovery using purely link-local Multicast DNS enables discovery of services that are on the local link, but not (without some kind of proxy or similar special support) discovery of services that are outside the local link. Using a very large local link with thousands of hosts facilitates service discovery, but at the cost of large amounts of multicast traffic. Performing DNS-Based Service Discovery using purely Unicast DNS is more efficient and doesn't require excessively large multicast domains, but requires that the relevant data be available in the Unicast DNS namespace. This can be achieved by manual DNS configuration (as has been done for many years at IETF meetings to advertise the IETF Terminal Room printer) but this is labor intensive, error prone, and requires a reasonable degree of DNS expertise. The Unicast DNS namespace can be populated with the required data automatically by the devices themselves, but that requires configuration of DNS Update keys on the devices offering the services, which has proven onerous and impractical for simple devices like printers and network cameras. Hence, to facilitate efficient and reliable DNS-Based Service Discovery, a compromise is needed that combines the ease-of-use of Multicast DNS with the efficiency and scalability of Unicast DNS.


Stuart Cheshire

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)