A computer or server does not work with domain names, like we know them, but uses IP addresses to identify computers within a network (or the internet). An IP address is a series of numbers, like “192.168.1.1” (IPv4) or “3ffe:6a88:85a3:08d3:1319:8a2e:0370:7344” (IPv6).
To make things easier for us as a human, domain names were created. At least a name is easier to remember than a series of numbers (IP). The system that is responsible for the translation of a domain name to the correct IP address is called DNS, or Domain Name Service. Translating the domain to an IP is done via a DNS server, which receives a request (the domain name), and returns the correct IP address.
Thanks to this system, we can use easy-to-remeber domain names to browse the internet, without having to know complicated IP addresses.
A typical client-server interaction, so you can browse to a certain domain name, might look as follows:
- You type the address in your browser (ie: ‘www.nucleus.be’)
- The request is launched to the DNS server, to translate this domain name to its correct IP address.
- Your computer receives the IP address
- The browser makes a connection to the server with this IP address, to display the website
The DNS server will keep a cache, or a local copy, of these IP addresses. This causes it to take a while before DNS changes are propagated to everyone. The DNS server will first try to translate the request through its cache, and once a certain time limit is exceeded it will launch a new request, to refresh the cache.
In theory, any changes made to the DNS system should be propagated throughout the world within 24 hours. In Belgium, this usually takes 4 to 8 hours.