Sometimes there is an issue with your DNS resolvers caching the domain name to IP mapping. When you're trying to go to the domain, it's actually pulling up an old IP address instead of looking for a new one and finding the correct record. So, to expedite this very common problem of cached DNS, please do the following steps.
Microsoft Windows XP
Close your application (e.g. browser or email).
Go to the Start menu, choose Run, type cmd and hit OK. When the black screen appears, type the following command and hit enter.
ipconfig /flushdns
Restart your application (e.g. browser or email).
Microsoft Windows Vista and Windows 7
Close your application (e.g. browser or email).
Click the Start orb and follow All Programs > Accessories, look for Command Prompt. Be sure to right click on Command Prompt and choose "Run as Administrator". When the black screen appears, type the following command and hit enter.
ipconfig /flushdns
Restart your application (e.g. browser or email).
Mac OSX
Navigate to your Applications folder, open Utilities, and double click on Terminal. Type the following command and hit enter.
dscacheutil -flushcache
Then type this command and hit enter.
lookupd -flushcache
Don't worry if either command says something like "Not found".
Restart your application (e.g. browser or email).
Linux
Open up a root terminal window (ctrl T in gnome). Type the following command and hit enter.
/etc/init.d/nscd restart
Restart your application (e.g. browser or email).
