The Domain Naming System is a hierarchical method of naming computers on the Internet. A DNS maintains a database of host names and IP addresses. Consequently, when a query is sent to a DNS server, it will be answered with the hostname instead of a numeric address. This name is what we see in the address bar of our browser.
For example, if the domain name domain.gr is hosted on a server with IP address 10.0.23.23, then the domain name server will convert the name domain.gr to this IP.
Note: Registered domain names must list at least 2 nameservers, one primary and one secondary nameserver. The DNS server is also responsible for distributing the information of a domain name zone, translating the domain name to an IP address, and determining the mail server responsible for the distribution of emails.