DNS- The Domain Name System is the hierarchical and decentralized naming system used to identify computers, services, and other resources reachable through the Internet or other Internet Protocol networks. The resource records contained in the DNS associate domain names with other forms of information. DNS is important because of its critical role as the backbone of the internet.
If a DNS is not responding, you won't be able to connect to other websites on the internet.
This is due to the fact that when a web browser is opened and the desired website is to be visited, you do not have to go through the stress of remembering and entering a long number (IP address). You simply enter a domain name and end up exactly where you are supposed to.
If the DNS cannot translate the domain name to the correct IP address, you won't be able to access any website. Simply put, without DNS, the majority of the internet as we know it breaks down.