The DNS

What is the DNS?

Electronic devices such as computers or mobile phones that are connected to a network are able to communicate with each other by using numerical identifiers.

When humans want to interact with these devices (e.g. when consulting a webpage or sending an email) these identifiers are translated into a meaningful format. The CENTR website can be found at 88.151.243.60. By entering this number into your browser you will end up on our homepage. It is however much easier to type www.centr.org in order to find the page you are looking for.

The DNS is the hierarchical distributed naming system that translates the numerical identifiers into domain names.

How does it work?

The DNS is a hierarchical system. In left-to-right scripts the highest level is at the end of the string. In http://www.centr.org, ".org" is the highest level. This level contains the information about the second level "centr" in our example. So when you type in a domain name, your computer will first consult the servers that contain the information for the .org zone. With the response it receives, your computer will then ask the second level centr.org where it can find the address of the third level www.centr.org. Then your computer will fetch that webpage and display it on your screen. And all this happens in just a few milliseconds.

The following movie explains it a bit more in detail:

 
 

 

 

Who runs it?

There are many different parties involved in the operation of the Domain Name System.

The companies that run the top level domains are called REGISTRIES. They maintain the database that contains all the information about their zone. That database is called the zonefile.

The companies that sell the domain names to website owners are the REGISTRARS. Typically they do not only sell domain names but provide a wide range of additional services such as hosting, internet access or website building.

The organisation that is in charge of coordinating the global policies for the domain name system is called ICANN (The Internet Corporation for Assigned Names and Numbers).

Where does it fit in the internet ecosystem?

The Domain Name System (DNS) is part of the technical layer of the internet. Packets travel between connected devices over the infrastructure built by Internet Service Providers and according to protocols agreed upon by the Internet Engineering Task Force (IETF) and the Internet Architecture Bureau (IAB). All of these packets receive an IP address managed by their Regional Internet Registry (RIR). The DNS adds a level of usability and security. The image below shows that layered structure and puts it in the context of the internet governance ecosystem. You will find the DNS' main actors in the bottom layer.