The DNS server is a zone wherein a number of domain names are registered. The server maybe dedicated to a university, or at the national level. For instance, .in represents Indian websites. Another example is .uk, for sites in the United Kingdom.
The other mainstream DNS servers include .com, .org, .net, etc. Using these servers, people register their domain names and have sites uploaded. Generally, DNS hosts purchase server space and then sell the space to individuals and entities that require space on the Internet for their websites or web pages.
The price of the server space depends on the prominence of the server. For instance, space on .com will cost far more than space on .in. Another aspect that determines price is the amount of space required. This depends on whether the individual or entity is looking at setting up a couple of files or web pages, or an entire site or web portal.
The DNS server is one of primary aspects of the Internet. Without it one would not be able to gain any space on the web. And if the servers were not well organized then there would be utter confusion. So what may seem like simple web surfing is actually based on a complex networking system.
What is worth noting is that the same domain name can be used on any of the servers. For instance, suppose the domain name you opt for is yourfood; the same domain name can be used for the various servers. So you can have yourfood.com, yourfood.in and yourfood.org on separate web-hosts, or a single individual or entity can purchase a domain name on all the servers.
One would think that because of the innumerable sites and pages up on the Internet it would be next to impossible find web space. But this is one world with infinite space, for one and all. As far as domain name availability is concerned, it’s all about creativity. So while the DNS server has a lot of space, it is up to you to invent new names.