OS X log DNS resolution

gistfile1.txt

P.S. In case anyone is following along at home, here's a bash script that observes the system log to determine which DNS server OS X is using to resolve google.com, for instance:

  # enable logging on mDNSResponder
  sudo killall -USR1 mDNSResponder
  # set logging to the maximum
  sudo syslog -c  mDNSResponder -d
  # start capturing log to a temporary file
  syslog -w 0 | grep GetServerForQuestion > /tmp/resolutionquery.log &
  # use python to resolve an address using the POSIX API
  python -c "import socket;socket.gethostbyname_ex('google.com');"
  # stop capturing the log
  jobs -p | xargs kill -SIGINT
  # shut off increased logging
  sudo killall -USR1 mDNSResponder
  # display captured output
  cat /tmp/resolutionquery.log

Then you look for the log entries for GetServerForQuestion.

From https://lists.apple.com/archives/macnetworkprog/2012/Jul/msg00010.html