Tip: Primary DNS servers are sometimes called preferred DNS servers and secondary DNS servers are sometimes called alternate DNS servers. Primary and secondary DNS servers can be “mixed and matched” to provide another layer of redundancy.
In general, DNS servers are referred to as all sorts of names, like DNS server addresses, internet DNS servers, internet servers, DNS IP addresses, etc.
Why Use Different DNS Servers?
One reason you might want to change the DNS servers assigned by your ISP is if you suspect there’s a problem with the ones you’re using now. An easy way to test for a DNS server issue is by typing a website’s IP address into the browser. If you can reach the website with the IP address, but not the name, then the DNS server is likely having issues.
Another reason to change DNS servers is if you’re looking for a better performing service. Many people complain that their ISP-maintained DNS servers are sluggish and contribute to a slower overall browsing experience.
Yet another, increasingly common reason to use DNS servers from a third party is to prevent logging of your web activity and to circumvent the blocking of certain websites.
Know, however, that not all DNS servers avoid traffic logging. If that’s what you’re after, make sure you read all the details about the server to know if that’s the one you want to use.
Finally, in case there was any confusion, free DNS servers do not give you free internet access! You still need an ISP to connect to for access – DNS servers just translate IP addresses and domain names.
Verizon DNS Servers & Other ISP Specific DNS Servers
If, on the other hand, you want to use the DNS servers that your specific ISP, like Verizon, AT&T, Comcast/XFINITY, etc., has determined is best, then don’t manually set DNS server addresses at all – just let them auto assign.
Verizon DNS servers are often listed elsewhere as 126.96.36.199, 188.8.131.52, 184.108.40.206, 220.127.116.11, and/or 18.104.22.168, but those are actually alternatives to the Level 3 DNS server addresses shown in the table above. Verizon, like most ISPs, prefers to balance their DNS server traffic via local, automatic assignments. For example, the primary Verizon DNS server in Atlanta, GA, is 22.214.171.124 and in Chicago, is 126.96.36.199.
The Small Print
Don’t worry, this is good small print!
Many of the DNS providers listed above have varying levels of services (OpenDNS, Norton ConnectSafe, etc.), IPv6 DNS servers (Google, DNS.WATCH, etc.), and location specific servers you might prefer (OpenNIC).
While you don’t need to know anything beyond what I included in the table above, this bonus information might be helpful for some of you, depending on your needs:
 The free DNS servers listed above as Level3 will automatically route to the nearest DNS server operated by Level3 Communications, the company that provides most of the ISPs in the US their access to the internet backbone. Alternatives include 188.8.131.52, 184.108.40.206, 220.127.116.11, 18.104.22.168, 22.214.171.124, and 126.96.36.199. These servers are often given as Verizon DNS servers but that is not technically the case. See discussion above.
 Verisign says this about their free DNS servers: “We will not sell your public DNS data to third parties nor redirect your queries to serve you any ads.” Verisign offers IPv6 public DNS servers as well: 2620:74:1b::1:1 and 2620:74:1c::2:2.
 Google also offers IPv6 public DNS servers: 2001:4860:4860::8888 and 2001:4860:4860::8844.
 DNS.WATCH also has IPv6 DNS servers at 2001:1608:10:25::1c04:b12f and 2001:1608:10:25::9249:d69b. In an uncommon but much-appreciated move, DNS.WATCH publishes live statistics for both of their free DNS servers. Both servers are located in Germany which could impact performance if used from the US or other remote locations.
 OpenDNS also offers DNS servers that block adult content, called OpenDNS FamilyShield. Those DNS servers are 188.8.131.52 and 184.108.40.206. A premium DNS offering is also available, called OpenDNS Home VIP.
 The Norton ConnectSafe free DNS servers listed above block sites hosting malware, phishing schemes, and scams, and is called Policy 1. Use Policy 2 (220.127.116.11 and 18.104.22.168) to block those sites plus those with pornographic content. Use Policy 3 (22.214.171.124 and 126.96.36.199) to block all previously mentioned site categories plus those Norton deems “non-family friendly.” Be sure to check out the list of things blocked in Policy 3 – there are several controversial topics in there that you may find perfectly acceptable.
 GreenTeamDNS “blocks tens of thousands of dangerous websites which include malware, botnets, adult related content, aggressive/ violent sites as well as advertisements and drug-related websites ” according to their FAQ page. Premium accounts have more control.
 Register here with SafeDNS for content filtering options in several areas.
 The DNS servers listed here for OpenNIC are just two of many in the US and across the globe. Instead of using the OpenNIC DNS servers listed above, see their complete list of public DNS servers here and use two that are close to you or, better yet, let them tell you that automatically here. OpenNIC also offers some IPv6 public DNS servers.
 FreeDNS says that they “never log DNS queries.” Their free DNS servers are located in Austria.
 Alternate DNS says that their DNS servers “block unwanted ads” and that they engage in “no query logging.” You can sign up for free from their signup page.
 Yandex’s Basic free DNS servers, listed above, are also available in IPv6 at 2a02:6b8::feed:0ff and 2a02:6b8:0:1::feed:0ff. Two more free tiers of DNS are available as well. The first is Safe, at 188.8.131.52 and 184.108.40.206, or 2a02:6b8::feed:bad and 2a02:6b8:0:1::feed:bad, which blocks “infected sites, fraudulent sites, and bots.” The second is Family, at 220.127.116.11 and 18.104.22.168, or 2a02:6b8::feed:a11 and 2a02:6b8:0:1::feed:a11, which blocks everything that Safe does, plus “adult sites and adult advertising.”
 UncensoredDNS (formerly censurfridns.dk) DNS servers are uncensored and operated by a privately funded individual. The 22.214.171.124 address is anycast from multiple locations while the 126.96.36.199 one is physically located in Copenhagen, Denmark. You can read more about them here. IPv6 versions of their two DNS servers are also available at 2001:67c:28a4:: and 2a01:3a0:53:53::, respectively.
 Hurricane Electric also has an IPv6 public DNS server available: 2001:470:20::2.
 puntCAT is physically located near Barcelona, Spain. The IPv6 version of their free DNS server is 2a00:1508:0:4::9.