Zeroconf

Courtesy of the IETF Zeroconf Working Group, by way of AppleTalk, NETBIOS, IPX and countless other nonstandardized protocols, Zero Configuration Networking attempts to simplify and automate local area networking (especially in the absence of suitable UIs). On UNIX, Avahi provides the mainstream Linux Zeroconf implementation; it is known as Bonjour on Apple products. Zeroconf's primary technologies include:

• Uni- and multicast address autoconfiguration via Link-Local Addressing (typically static, or managed via DHCP)
• Name translation via Multicast DNS (mDNS) (typically static, or managed via DNS)
• Service discovery via DNS Service Discovery (DNS-SD) (typically managed via a directory server)

Service Discovery

Service Type Enumeration

Service types can be enumerated by querying _services._dns-sd._udp.domain for a given domain. The reply is a set of PTR records.

• Avahi seems to support Service Type Enumeration, while Bonjour does not (November 2011)

Service Instance Enumeration

Rather than using the SRV record, SD makes use of PTR.

• The temporary SRV Record Type registry was closed in 2010...
• ...and rolled into the RFC 6335-conformant United Service Name and Transport Number Registry

See also

• "DNS-based Service Discovery" Stuart Chesire, 2011-02-27.
• "Zero-configuration Networking: The Definitive Guide" from O'Reilly