What are Name Servers & Why Do You Need To Change Them?
Introduction
Have you ever had to set up a new domain? Well if you’re reading this, chances are the answer is yes. In many cases you won’t need to worry about name servers, and you can go on your merry way. However if you buy your domain at domain.com, but you want to use Cloudflare as your DNS, you’ll have to change your name servers. While this is usually well documented and an easy process, very few places tell why you have to do it.
Before answering the question that brought you here, you’ll first need to understand root servers and their role in DNS.
Root Servers
Root servers are the basis of DNS. Without them the whole thing simply wouldn’t work. They’re called root for a reason. The importance of them are best explained through an example. Let’s say that you want to access medium.com
We’ll start by assuming that everything has a cold cache, meaning nothing is stored anywhere. The first thing that will happen when you enter medium.com in your browser, is that your computer will reach out to your local resolver. If it can’t find the answer there (which it won’t in this case), it will send a request to your configured DNS server for the IP.
Because the DNS server doesn’t have the IP cached, it will reach out to a root server. This root server won’t have the IP stored either, but it will have a list over TLD servers. The DNS server will now reach out to the TLD server, and ask for the name server needed for medium.com
This is where the configuration of the name servers become important.
Name Servers
Name servers are largely key-value stores. In this case it will contain the key will be medium.com, and as of writing this the value can be 104.16.120.127. At some point during medium.com’s lifetime, they’ve decided to use Cloudflare as their DNS, however that doesn’t necessarily mean that’s their domain registrar. Maybe they bought their domain from GoDaddy.
Assuming the above example is correct, Medium will have had to change their name servers, from using GoDaddy’s to using Cloudflare’s. So what does this mean in technical terms?
As previously mentioned, the TLD server will respond with an authoritative name server, which your configured DNS server will request the IP from. In the above example, the TLD server has been told that it should no longer use GoDaddy to respond to requests for medium.com, but that it should use Cloudflare.
Conclusion
While DNS can sometimes seem like dark magic, in reality it’s an incredibly robust but relatively simple system. Name servers are basically giant key-value stores, and when you are changing them, you are telling the TLD server who should resolve requests to your domain.
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