Google Public DNS

Instead of using your ISP DNS server IP address, you can use Google DNS instead such as follows:
8.8.8.8
8.8.4.4
So why go all the hassle and use Google DNS instead, well, some people had claimed that their browsing speed to certain sites had improved. There is no need to use it if your browsing speed is decent enough though.
Link: http://code.google.com/intl/en/speed/public-dns/docs/using.html