DNS request are usually cached to speed up the lookups within the same host. If you need to clear that DNS cache for some reason, here are the simple Terminal shortcuts for it.
Flush DNS cache: Mac OS X Tiger and below
Clearing the DNS cache is as easy as entering the command below into a Terminal and hitting enter.
Clear DNS cache: Mac OS X Leopard
In Mac OSX 10.5 Leopard, the above command will not work. This is because a different command replaces flushcache. To clear DNS cache in OS X Leopard, enter the command below into a Terminal and hit enter.ADVERTISEMENT
What is DNS?
The Domain Name System (DNS) is a naming system for computers, and anything else on the Internet. When you type a website’s name into your browser addressbar, the DNS gives you the IP co-ordinates to find the server.