DNS (Domain Name Server) is a service that provides a translation of an easy-to-remember Internet address (e.g. google.com) to the actual IP address. Thanks to DNS, you just have to remember the Internet domain names instead of IP addresses. This service operates in the background and is taken care of by your router or your Internet service provider (ISP). In practice, the name of the webpage entered by the user is translated to the numerical IP address from where your computer reads all the necessary data.
What is the DNS good for and how does it work?
The basic idea of DNS is to spare the Internet users the difficulty of having to remember numerical IP addresses (e.g. 188.8.131.52), i.e. numbers that are essential for computers and Internet functioning. Instead, while browsing, users just have to remember names (words instead of numbers, e.g. www.managementmania.com) that are easy to remember by us - human beings. DNS servers contain a database of IP addresses of all Internet domains (e.g. google.com). As soon as you enter this domain name into your Internet browser, your computer asks the DNS server for the IP address in order to redirect you. This communication is happening without even you noticing it.
In fact, the DNS could be compared to a phonebook where, instead of names of people, there are names of Internet domains, and instead of phone numbers, there are IP addresses. This way, the DNS system enables to pair the numerical IP addresses with concrete names that are easily remembered by the users and that are easy to type, for example, to the web browser. Then, the browser have a look in the “phonebook” (DNS server), find the corresponding record, automatically connect to the correct IP address and then show the website. This can be abused by a potential attacker who could slip in a fake DNS server. A secured DNS is referred to as DNSSEC.
The DNS service is distributed around the world. Logically, it cannot be operated by a single computer. Therefore, DNS servers are organized into a system of layers. This means that for each layer, there is a separate DNS. For instance, the first layer (TLD) could be for example “.com” or “.net” and the second layer (SLD) could be for example “mycompany”. Besides, every domain is assigned two or more root name servers to help with the translation. Furthermore, the entire system is deployed and synchronized worldwide.
TIP: When you change the domain or IP address, you can notice that a website operated by one internet provider loads quicker than a website from another one. This is because the communication with all the DNS takes a while.