list of free DNS that you can use,
Google Public DNS
Primary server: 220.127.116.11
Secondary server: 18.104.22.168
Google operates the world’s largest public DNS service. Launched in December 2009, it supports many billions of DNS queries per day, much of the volume generated from clients outside the U.S. The company developed this service as one of its corporate initiatives to make the Internet more accessible and easier for everyone to use, making it a logical choice for users worldwide.
Primary server: 22.214.171.124
Secondary server: 126.96.36.199
The oldest of all services on this list, OpenDNS also supports billions of DNS queries per day. In addition to its basic name resolution service, OpenDNS Home Solutions provides free Web site filtering of adult content (called FamilyShield) and URL spell correction with accompanying installed software. The company also sells various security products to businesses. Those looking for an alternative to Google products and a service that works well outside the U.S. also tend to like OpenDNS.
Norton DNS for Home
Secondary server: 188.8.131.52
Security software company Symantec began offering its free Norton DNS in 2010. The package works similarly to OpenDNS FamilyShield. Utility programs that automatically configure the DNS server addresses 184.108.40.206 and 220.127.116.11 and set up basic content filtering exist for Windows, Mac OS X and Android. Those already using OpenDNS or Google Public DNS but dissatisfied with those service can try Norton DNS to see how it compares.
Comodo Secure DNS
Primary server: 18.104.22.168
Secondary server: 22.214.171.124
In addition to its free DNS service, Comodo is known for the Antivirus package it sells along with other software products.
Primary server: 126.96.36.199
Secondary server: 188.8.131.52
A company called Neustar manages both the free DNS Advantage service as well as the commercial (not free) UltraDNS system.
Primary server: 184.108.40.206
Secondary server: 220.127.116.11
Designed to automatically block pornographic and other undesirable Web sites, ScrubIT made its debut in 2007 and received mixed reviews for its aggressive filtering policy.
Verizon / Level 3 CommunicationsU.S Internet provider
Primary server: 18.104.22.168
Secondary server: 22.214.171.124
Verizon maintains public DNS servers that can be used by both subscribers and non-subscribers. Verizon’s servers (sometimes identified as “Level 3 Communications” or as “Genuity” / “gtei.net”).