To save some time in addressing a DNS query, your computer is caching the result for 24 hours.
As a matter of fact, this process may create some issues when you happen to transfer your domain to a new IP address as your computer will try to resolve to the old IP and will delay the corrupted cache for another 24 hours. The output will be a 404 not found error on your browser, while your domain is running properly for your visitors.

You could always check your website through a web proxy or a VPN to be able to see that your website is running properly.

The DNS cache is included in several places and you need to clear them all to access your websites, such as : the browser cache, the OS and the router.

Or you could clear your DNS cache following the steps below :

** It is important to go through all the steps without accessing your websites in between since one DNS cache may corrupt the other**

How to clear your DNS cache on Windows

1) Open a command prompt (Start Menu, Run, and type CMD)

2) Type the following command : ipconfig /flushdns

3) Empty your browser cache

4) Restart your router by leaving it unplugged for 30 seconds to reset its cache

5) Done !

How to clear your DNS cache on Mac OS X

1) Open your Terminal and type :

a) On Leopard : lookupd -flushcache
b) On others version of OS X : dscacheutil -flushcache

2) Done!

Please note, that your router / modem may have its own DNS cache and it is recommanded that you plug it off for 30 seconds in order to flush it, or it may corrupt your computer's DNS cache.

How to clear your DNS cache in Linux

1) Open your Terminal and type :

/etc/rc.d/init.d/nscd restart

2) Done!

Please note, that your router / modem may have its own DNS cache and it is recommanded that you plug it off for 30 seconds in order to flush it, or it may corrupt your computer's DNS cache.