When your computer wants to connect to a website or service on the internet, it does so by communicating to servers(s) by using an identifier called an “IP address”. An IP address is made up of four sets of numbers, for example 10.0.0.1. (For more details on IP addresses, check out some of the articles on our website).
If you know device knows the IP address of the server it wants to communicate with, and it has its IP address it can try contacting the server. However, this system has a built-in difficulty that is immediately clear once you are trying to connect to devices on the internet. Devices in your network also use IP addresses and usually *someone* knows which IP belongs to what device.
However, when you want to connect to a server on the internet, there are two difficulties that arise:
- What is the IP of the server you need to contact?
- Many servers on the internet host more than one website or a copy of a service.
As far as IP addresses go, there are 4,294,967,296 potential IP addresses out there. And that’s just the old version of IP addresses, there’s also 340 trillion IPV6 addresses that can possibly belong to the server you are looking for.
If you would have to test all IP addresses to find the site you are looking for, and it took you one second per IP address, it would take you 126 years to test them all!
As we mentioned, one IP can host multiple websites or services. That creates another problem, because we need a way to tell this server which one of the sites or services you are interested in.
Both of these systems are solved by a system called DNS, which stands for Domain Name Service.
The DNS service offers a system of easy – well, easy-ish – to remember “domain names which are pointed to IP addresses using a system of different types of DNS servers that work together.
When you enter a domain name, for example in your browser, your device will ask a “DNS server” where it can find the IP address for a domain name, for example ARP20.com. Your device will then use that IP to contact the server and tell it what domain it is looking for so that the server can return the proper website or service.
If, on the other hand, the DNS server can’t find the IP address for the domain name – or the DNS server isn’t operating properly – you’ll get an error that the domain name can’t be resolved.
DNS servers exist in many shapes and forms. You can choose which DNS server you want to use. In many case, people use the default DNS servers of their ISP but choosing an alternative DNS server can also increase the security of you and your network. We’ll cover this in another article.