DNS

Domain Name System (DNS): A global and highly distributed network service that resolves strings of letters, such as a website name, into an IP address

When you connect to a network, ​you’re using the DNS server address that ​was provided by the router you connected to. ​It updates your network setting to ​use that DNS server address, ​which is usually your ISP’s DNS server. ​From there, you’re able to ​access pretty much any website. ​

Why do you need to set up your own DNS servers? ​The DNS just works out of the box… 2 Reasons:

1. First, if you’re running a web service like a website, ​you want to be able to tell ​the Internet what IP address to reach your website. ​To do that, you need to set up DNS.
2. The second reason is that you probably want to work ​on your server or user machines remotely. ​In theory, you could remote ​access into them through an IP address, ​but you could also just ​use an easy to remember host name. ​To do that, you need DNS to ​map the IP address to the host name.