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Emptying the system's DNS cache
Your computer keeps the IP addresses of sites visited locally in order to find them again more quickly the next time without having to consult with the DNS servers. But if there have been any changes concerning your site (a server being moved, for example) and you notice something strange, it may be useful to empty the DNS cache before looking at it again.
Start > Run > type cmd
In the DOS window, type ipconfig /flushdns
Check that the "Command prompt" window is in "Administrator" mode by looking at the run mode indicated in its header bar.
Under MacOS X
Type lookupd -flushcache in the terminal
Type /etc/rc.d/init.d/nscd restart in a terminal to relaunch nscd