mDNSShared/mDNSResponder.8

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  17 .Dd April 2004              \" Date
  18 .Dt mDNSResponder 8         \" Document Title
  19 .Os Darwin                  \" Operating System
  20 .\"
  21 .Sh NAME
  22 .Nm mDNSResponder
  23 .Nd Multicast and Unicast DNS daemon    \" Name Description for whatis database
  24 .\"
  25 .Sh SYNOPSIS
  26 .Nm
  27 .\"
  28 .Sh DESCRIPTION
  29 .Nm
  30 (also known as
  31 .Nm mdnsd
  32 on some systems)
  33 is a daemon invoked at boot time to implement Multicast DNS and DNS Service Discovery. On
  34 Mac OS X 10.6 (Snow Leopard),
  35 .Nm
  36 is also the system-wide Unicast DNS Resolver.
  37 .Pp
  38 .Nm
  39 listens on UDP port 5353 for Multicast DNS Query packets.
  40 When it receives a query for which it knows an answer,
  41 .Nm
  42 issues the appropriate Multicast DNS Reply packet.
  43 .Pp
  44 .Nm
  45 also performs Unicast and Multicast DNS Queries on behalf of client processes, and
  46 maintains a cache of the replies.
  47 .Pp
  48 .Nm
  49 has no user-specifiable command-line argument, and users should not run
  50 .Nm
  51 manually.
  52 .Pp
  53 .Sh LOGGING
  54 There are several methods with which to examine
  55 .Nm Ns 's internal state for debugging and diagnostic purposes. The syslog(1)
  56 logging levels map as follows:
  57 .Pp
  58 .Dl Error - Error messages
  59 .Dl Warning - Client-initiated operations
  60 .Dl Notice - Sleep proxy operations
  61 .Dl Info - Informational messages
  62 .Pp
  63 By default, only log level Error is logged.
  64 .Pp
  65 A SIGUSR1 signal toggles additional logging, with Warning and Notice
  66 enabled by default:
  67 .Pp
  68 .Dl % sudo killall -USR1 mDNSResponder
  69 .Pp
  70 Once this logging is enabled, users can additionally use syslog(1)
  71 to change the log filter for the process. For example, to enable log levels Emergency - Debug:
  72 .Pp
  73 .Dl % sudo syslog -c mDNSResponder -d
  74 .Pp
  75 A SIGUSR2 signal toggles packet logging:
  76 .Pp
  77 .Dl % sudo killall -USR2 mDNSResponder
  78 .Pp
  79 A SIGINFO signal will dump a snapshot summary of the internal state to
  80 .Pa /var/log/system.log Ns :
  81 .Pp
  82 .Dl % sudo killall -INFO mDNSResponder
  83 .Sh FILES
  84 .Pa /usr/sbin/mDNSResponder \" Pathname
  85 .\"
  86 .Pp
  87 .Sh INFO
  88 .Pp
  89 For information on Multicast DNS, see
  90 .Pa http://www.multicastdns.org/
  91 .Pp
  92 For information on DNS Service Discovery, see
  93 .Pa http://www.dns-sd.org/
  94 .Pp
  95 For information on how to use the Multicast DNS and the
  96 DNS Service Discovery APIs on Mac OS X and other platforms, see
  97 .Pa http://developer.apple.com/bonjour/
  98 .Pp
  99 For the source code to
 100 .Nm , see
 101 .Pa http://developer.apple.com/darwin/projects/bonjour/
 102 .\"
 103 .Sh BUGS
 104 .Nm
 105 bugs are tracked in Apple Radar component "mDNSResponder".
 106 .\"
 107 .Sh HISTORY
 108 The
 109 .Nm
 110 daemon first appeared in Mac OS X 10.2 (Jaguar).
 111 .Pp
 112 Also available from the Darwin open source repository
 113 (though not officially supported by Apple) are
 114 .Nm
 115 daemons for other platforms, including Mac OS 9, Microsoft Windows,
 116 Linux, FreeBSD, NetBSD, Solaris, and other POSIX systems.