To flush DNS cache in Microsoft Windows:
- Start -> Run -> type cmd
 - in command prompt, type ipconfig /flushdns
 - Done! You Window DNS cache has just been flush.
To flush the DNS cache in Linux, restart the nscd daemon:
- To restart the nscd daemon, type /etc/rc.d/init.d/nscd restart in your terminal
 - Once you run the command your linux DNS cache will flush.
To flush the DNS cache in Mac OS X Leopard:
- type lookupd -flushcache in your terminal to flush the DNS resolver cache.
 ex: bash-2.05a$ lookupd -flushcache
 - Once you run the command your DNS cache (in Mac OS X) will flush.
To flush the DNS cache in Mac OS X:
- type dscacheutil -flushcache in your terminal to flush the DNS resolver cache.
 ex: bash-2.05a$ dscacheutil -flushcache
 - Once you run the command your DNS cache (in Mac OS X Leopard) will flush.