NAME
mdnsd —
Multicast and Unicast DNS
daemon
SYNOPSIS
mdnsd |
DESCRIPTION
mdnsd (also known as
mDNSResponder on some systems) is a daemon invoked at
boot time to implement Multicast DNS and DNS Service Discovery. On Mac OS X
10.6 (Snow Leopard), mdnsd is also the system-wide
Unicast DNS Resolver.
mdnsd listens on UDP port 5353 for
Multicast DNS Query packets. When it receives a query for which it knows an
answer, mdnsd issues the appropriate Multicast DNS
Reply packet.
mdnsd also performs Unicast and Multicast
DNS Queries on behalf of client processes, and maintains a cache of the
replies.
mdnsd has no user-specifiable command-line
argument, and users should not run mdnsd
manually.
LOGGING
There are several methods with which to examine
mdnsd's internal state for debugging and diagnostic
purposes. The
syslogd(8) logging levels map as follows:
Error - Error messagesWarning - Client-initiated
operationsNotice - Sleep proxy
operationsInfo - Informational
messagesBy default, only log level Error is logged.
A SIGUSR1 signal toggles additional logging, with Warning and Notice enabled by default:
# pkill -USR1 mdnsdA SIGUSR2 signal toggles packet logging:
# pkill -USR2 mdnsdA SIGINFO signal will dump a snapshot summary of the internal state to /var/log/system.log:
# pkill -INFO mdnsdFILES
/usr/sbin/mdnsd
SEE ALSO
dns-sd(1), pkill(1), syslogd(8)
For information on Multicast DNS, see http://www.multicastdns.org/
For information on DNS Service Discovery, see http://www.dns-sd.org/
For information on how to use the Multicast DNS and the DNS Service Discovery APIs on Mac OS X and other platforms, see http://developer.apple.com/bonjour/
For the source code to mdnsd, see
http://developer.apple.com/darwin/projects/bonjour/
HISTORY
The mdnsd daemon first appeared in Mac OS
X 10.2 (Jaguar).
Also available from the Darwin open source repository (though not
officially supported by Apple) are mdnsd daemons for
other platforms, including Mac OS 9, Microsoft Windows, Linux,
FreeBSD, NetBSD, Solaris,
and other POSIX systems.
BUGS
mdnsd bugs are tracked in Apple Radar
component "mDNSResponder".