DNS

DNS = Domain Name System

Explanation
The DNS is mainly used to access entities in the network via a name (e.g. 'wikipedia.org' or 'Phone82338') instead of an IP addresses (e.g. 66.230.200.100 or 192.168.1.66). This is more intuitive for users (e.g. trying to access the user web page of a phone) and more flexible (e.g. if IP server address is changing while installing other components - the domain name remains unchanged).