# dscacheutil
# Gather info, stats and initiate queries to the Directory Service cache.

# Flush the DNS cache
# in OS X 10.9 Mavericks
dscacheutil -flushcache

# to clear DNS cache in 10.7 and 10.8
killall -HUP mDNSResponder

# Show DNS resolver statistics (Mac OS X)
dscacheutil -statistics