For your domain to work (e.g.: email, web, or any service), at least two DNS servers must be associated with it.
DNS stands for “domain name system.” Domain names are the website addresses that humans use everyday. For example, the domain name of Google is google.com. By entering google.com into your browser's address bar, you will be able to visit Google.
However, “google.com” is a web address which your computer doesn't know how to locate. The Internet and other networks use what is called numerical IP (Internet protocol) addresses. The IP address of Google.com is located at "184.108.40.206". Try to type these numbers in the address bar of your browser and you will be directed to Google.com.
Humans use google.com because it is more meaningful, readable and easier to remember. IP addresses are created for machines because computers understand numbers more easily. Think of DNS as a phone book. It replaces domain names with IP addresses that computers can easily understand.
Information from all the domain name servers across the Internet are collected together and stored at the Central Registry. Internet Service Providers and Host companies interact with the Central Registry on a regular schedule to get updated DNS information.
When you type in a web address, e.g., www.your-domain.com, its DNS will be viewed by your Internet Service Provider and will translate it into a computer-friendly IP address and will direct your Internet connection to the correct website.
If you don’t have DNS servers, you can use, free of charge, Marcaria.com DNS servers.
After you register a new domain name or when you update the DNS servers on your domain name, it usually takes between 6 and 48 hours for the domain name servers world-wide to be updated and able to access the information. Some countries are updated manually and can take longer. This period is referred to as propagation.