A domain name server (also called DNS) is the Internet’s equivalent to a phone book. A domain name server maintains a directory of domain names and their matching IP addresses. This information allows other computers to know where to go to find your website.
How? The information from all the domain name servers across the Internet is gathered into a Central Registry that is housed by an organization called ICANN. Computer networks across the world check in with the Central Registry on a regular basis to get updates so they will know information about your domain and where to find your domain name or your website if you have one.
Without a domain name server and the information it provides, computers wouldn’t know where to find your website or any other website.
It takes approximately 24 hours for your new or modified information that is entered into a domain name server to make it’s way across the internet.