mDNSResponder — Multicast DNS daemon




mDNSResponder (also known as mdnsd on some systems) is a daemon invoked
at boot time to implement Multicast DNS and DNS Service Discovery.

mDNSResponder listens UDP port 5353 for Multicast DNS Query packets.
When it receives a query for which it knows an answer, mDNSResponder
issues the appropriate Multicast DNS Reply packet.

mDNSResponder also performs Multicast DNS Queries on behalf of client
processes, and maintains a cache of the replies.

mDNSResponder has no user-specifiable command-line argument, and users
should not run mDNSResponder manually.

To examine mDNSResponder’s internal state, for debugging and disagnostic
purposes, send it a SIGINFO signal, and it will then dump a snapshot sum-
mary of its internal state to /var/log/system.log, e.g.

sudo killall -INFO mDNSResponder





For information on Multicast DNS, see
For information on DNS Service Discovery, see
For information on how to use the Multicast DNS and the DNS Service Dis-
covery APIs on Mac OS X and other platforms, see
For the source code to mDNSResponder, see


mDNSResponder bugs are tracked in Apple Radar component „mDNSResponder“.


The mDNSResponder daemon first appeared in Mac OS X 10.2 (Jaguar).

Also available from the Darwin open source repository (though not offi-
cially supported by Apple) are mDNSResponder daemons for other platforms,
including Mac OS 9, Microsoft Windows, Linux, FreeBSD, NetBSD, Solaris,
and other POSIX systems.


Share on FacebookTweet about this on TwitterPin on PinterestShare on Google+
Rbcafe © 2004- | Rb Cafe 1.3 | Kontakt Rbcafe | Rbcafe auf Twitter | Rbcafe auf Facebook | Datenschutz