macOS Sierra 10.12.0
sudo killall -HUP mDNSResponder
OSX 10.11.0
sudo killall -HUP mDNSResponder
OSX 10.10.4
sudo killall -HUP mDNSResponder
OSX 10.10.0 – 10.10.3
sudo discoveryutil mdnsflushcache
OSX 10.9 – 10.8 – 10.7
sudo killall -HUP mDNSResponder
OSX 10.5 – 10.6
sudo dscacheutil -flushcache
Windows:
ipconfig /flushdns
Linux (depending on what distribution you’re running)
/etc/init.d/named restart /etc/init.d/nscd restart