Many applications cache DNS entries to speed up DNS lookups in the event you request resources from the same server. Sometimes you need to flush this DNS cache if you know for a fact that a DNS entry has changed. How do you do that?
Flushing DNS On Windows
H:\>ipconfig /flushdns Windows IP Configuration Successfully flushed the DNS Resolver Cache.
Flushing DNS On Linux
To flush the DNS cache on Linux, restart the nscd daemon:
/etc/init.d/nscd restart
Flushing DNS On Mac OS X
In Mac OSX Leopard, you can use the command dscacheutil:
bash-2.05a$ dscacheutil -flushcache
In Mac OSX versions prior to 10.5.1, use the command lookupd:
bash-2.05a$ lookupd -flushcache