OSX:
10.10.4 or later:
sudo killall -HUP mDNSResponder
10.10 ~ 10.10.3:
sudo discoveryutil mdnsflushcache
10.7 ~ 10.9.5:
sudo killall -HUP mDNSResponder
10.6 ~ 10.6.8:
sudo dscacheutil -flushcache
Windows:
ipconfig /flushdns
OSX:
10.10.4 or later:
sudo killall -HUP mDNSResponder
10.10 ~ 10.10.3:
sudo discoveryutil mdnsflushcache
10.7 ~ 10.9.5:
sudo killall -HUP mDNSResponder
10.6 ~ 10.6.8:
sudo dscacheutil -flushcache
Windows:
ipconfig /flushdns