The Domain Name System protocol (DNS) is a query protocol whereby if the server is given a Domain Name, it will respond with the associated IP address. To use the system, a DNS server address must be added to your computers newtork configuration table. This can be done either by hard-coding the address into the table yourself, or if the service is available, by letting the ISP dynamically provide an address. Secondary addresses can usually also be added to the table as a fallback, should the primary address server fail.

Most ISPs operate their own private DNS servers, which are not accessable when your computer is using an IP address from another ISP (such as at a Wi-Fi hotspot), or which could become overloaded or go offline. These can be manually substituted with Public DNS servers, which are available to all IP address ranges, and which often (except in the case of the Google operated servers) are only lightly loaded. To access, set the computer to "Use the following DNS server addresses", which you will provide. Because DNS lookups can be a privacy concern (most ISPs log, and sometimes will even censor or redirect to an affiliate, DNS lookup requests made by your computer through their private DNS servers), many Public DNS servers differentiate themselves by having a non-censorship policy, and some also have an additional privacy policy of not keeping logs.

As Domain Names must be unique, an organization called the Internet Assigned Numbers Authority (IANA) has established itself to regulate the naming. Their authorized selling of name right leases has become a huge income business, with horror stories about squatting abuses, and about how Domain Names are unscrupulously snatched from legitimate leasees and given to wealthy corporations. There is no reason however why another agency could not regulate the issuance of Domain Names as well that do not conflict with IANA names, and which circumvent IANAs fee-charging monopoly. One such alternative naming authority, which offers FREE TLDs, is called "OpenNIC". The OpenNIC community offers a mailing list for technical and non-technical discussions about OpenNIC.

OpenNic TLDs
IANA TLDs

Unfortunately the profiteering IANA registrars and their top tier DNS servers refuse to regognize OpenNIC Domain Names (and these IANA servers are where most private ISP DNS servers look to populate their own lookup tables), so to reach these addresses you must use a public OpenNIC server (note that these OpenNic servers without prejudice also recognize all of the IANA DNS names as well). Don't set your computer to "Obtain DNS server address automatically", but instead set the computer to "Use the following DNS server addresses" (which you will provide). Below are addresses for public DNS servers, both OpenNic and IANA.
[IANA Port assignment = 853]