Mac OS X 清除DNS缓存

根据Mac OS X操作系统的版本选择以下命令：
Mac OS X 12 (Sierra) and later:

sudo killall -HUP mDNSResponder 
sudo killall mDNSResponderHelper 
sudo dscacheutil -flushcache

Mac OS X 11 (El Capitan) and OS X 12 (Sierra):

sudo killall -HUP mDNSResponder

Mac OS X 10.10 (Yosemite), Versions 10.10.4+:

sudo dscacheutil -flushcache
sudo killall -HUP mDNSResponder