Most computers on TCP/IP networks that need name resolution support use the Domain Name System (DNS)
. Setting up DNS on client devices requires identifying the DNS servers
to use. The DNS servers are installed by network administrators or, on the Internet, service providers.
Numerous providers have set up DNS servers on the Internet for free public access including the especially popular and well-known ones listed below. To utilize any of these services, specify the IP addresses of their primary and secondary DNS servers in a device's or network's TCP/IP configuration. Some providers also offer other optional services, such as site filtering, in addition to standard name resolution.
A good DNS server supports both high performance and reliability. Especially on high-traffic networks, DNS servers must handle a significant load of name and address look-ups to support Web browsing, email and other usages. DNS reliability can vary depending on the provider, and performance can vary depending on a client's location. Utility program like netbench or GRC DNS Benchmark are available online to help people identify and choose preferred public DNS servers for them based on diagnostic tests.
Do not confuse DNS server name resolution services with domain name registration services. These DNS servers can be accessed from any public Internet domain.
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. Google Public DNS utilizes servers at IP addresses 188.8.131.52 and 184.108.40.206. 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.
The oldest of all services on this list, OpenDNS also supports billions of DNS queries per day via its servers operating on 220.127.116.11 and 18.104.22.168. 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.
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 22.214.171.124 and 126.96.36.199 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.
In addition to its free DNS service, Comodo is known for the Antivirus package it sells along with other software products. Access the Comodo DNS servers at 188.8.131.52 and 184.108.40.206.
A company called Neustar manages both the free DNS Advantage service as well as the commercial (not free) UltraDNS system. Enter the DNS server addresses 220.127.116.11 and 18.104.22.168 to use DNS Advantage.
Addresses 22.214.171.124 and 126.96.36.199 belong to the ScrubIT free public DNS servers. 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 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") appear at 188.8.131.52 through 184.108.40.206.
GFI ClearCloud DNSThe free ClearCloud DNS was shut down in January, 2012.