Domain Name System/Service (DNS)

How can people remember the tedious IP addresses?

It is easier to remember cs.anu.edu.au than 150.203.164.35, isn't it?

cs, anu, edu, and au are all domain names.

There are many other domain names.

DNS keeps a mapping from domain names to IP addresses and the reverse.

Domain names can be composite.

E.g. business.act.gov.au, act.gov.au, gov.au are all valid domain names.

IP number / Postal Code  //  Domain Name / Town Name

pingu, www, cs	anu	com, edu, org	au, uk
Name or alias of a machine, or department	Entity (university,	Top Level Name	Country

pingu, www	research	ina, google	fr, com
Name or alias of the machine	department	Entity	Country or Top Level Name

www	ina, google	fr, com
Name or alias of the machine	Entity	Country or Top Level Name