DNS request are usually cached, that’s good as it help to speeds up the lookups within the same host but sometimes we will want to clear the cache so it don’t hold the values that are no longer valid. To clear DNS cache in Mac OSX, we can do it with the help of Terminal.
Recommended Reading: How to clear DNS in OS X Yosemite
Mac OSX 10.4 and below
Mac OSX 10.5 and above
However a Mac OSX 10.5 Leopard user will tell you this command will no longer work. In Mac OSX Leopard a new command has been used to replace
flushcache. To clear DNS cache in Leopard, use the following command: