DNS

Definition

A DNS (Domain Name System)[1] is a computer, which is used to match specific hostnames (like www.website.com) to their exact IP addresses stored in a DNS database.

When a user types a web address into a browser, the browser then sends a DNS query to a DNS server. The DNS server finds the needed IP address in its database and sends it back for the browser to be able to retrieve the contents of the webpage from this particular IP. 

The whole DNS resolution process requires several hardware components to interact with each other, with the key component in the raw being the primary DNS server. 

What are DNS servers used for? 

DNS servers spear us the need to memorize a lengthy numeric IP address like 148.251.213.126 and let us use human-language domain names instead. 

What is a DNS server example? 

For example, you can type http://157.240.20.35/ into your browser and get to Facebook directly. Or you can type in the domain name - facebook.com - and the DNS server will resolve your browser’s query to find the same IP address ( http://157.240.20.35/) to direct you to it. 

How does a DNS server resolve a query?

The typical DNS resolution process involves four independent servers, each playing its role at a particular stage. 

The first one in the raw is a DNS resolver (or a DNS recoursor[2]), which receives a new DNS request and passes it along to other machines to find the needed IP address.

The second to join in is a root nameserver. Depending on the domain TLD (like .com, .nl, .pl, etc.), the root nameserver sends the address of the needed TLD server. Simply speaking, it redirects the DNS resolver to a database, where information about websites with this particular TLD is stored. 

The third server to participate is a TLD nameserver. The TLD nameserver is still not the website IP address’s database itself, but more of a catalog of such databases. So, it sends DNS resolver the address of an authoritative nameserver which stores the IP of the website in question. 

And finally, by querying the authoritative nameserver, the resolver obtains the website’s IP address and sends it back to the browser.

How can I find my DNS server?

The router's admin interface status page is the best place to look up your DNS server's IP address. Every router has a pre-configured webpage, where all its key settings and attributes, including the DNS server’s IP address, can be accessed and re-configured.

What happens when DNS servers fail?

Today, DNS server outages have very little potential to influence our internet experience. This is mainly due to the fact that most servers and databases have backup copies. So, no matter whether an interruption in a certain nameserver’s operations was caused by a hardware problem, a power outage, or a hacker attack, in most cases the request will still be served by a backup version of the server. The only issue might be the connection speed in case of a high load on the backup server.