Nameserver

This is where the domain name is stored together with its IP address. It is like a telephone directory where you use a name (eg bbc.co.uk) to look up a number, in this case the IP address of a server, home computer or device, like a CCTV camera.

There are always 2 or more nameservers to provide resilience to a network. 20i has four. You move your website from one website host to another by changing the DNS record to point to a different nameserver.

The Doman Name Service (DNS) has hundreds of servers all over the world that are kept synchonised but changes can take a day or two to be updated everywhere.