Windows OS: Please open a command prompt windows and type command ipconfig /flushdns

With Mac OS X <= 10.4:

macvin:~ root# lookupd -flushcache

With Mac OS X > 10.5:

macvin:~ root# dscacheutil -flushcache

Some ISPs also cache domain dns, so you may need to wait 12-24 for dns cache refresh to complete a domain dns update.

You can use third party dns resolvers instead of your ISP dns resolvers

E.g. Google dns resolver IPs 8.8.8.8 and 8.8.4.4