Flush DNS cache in Lion and Mountain Lion Aug 08, '12 07:30:00AM • Contributed by: kirkmc I came across this Apple technical note this morning, which describes how to flush the DNS cache on your Mac. We have a hint for 10.5, which is also valid for 10.6, but we're not up to date. So, as a reminder, to flush the DNS cache in Mac OS X 10.5 and 10.6, run this command in Terminal: sudo dscacheutil -fl