Domain Name System/Service (DNS) (3)

Domain Name attributed by a Registrar or you local SysAdm

Domain names can be registered through many different companies (known as "registrars") that compete with one another.
The registrar you choose will ask you to provide various contact and technical information that makes up the registration. The registrar will then keep records of the contact information and submit the technical information to a central directory known as the "registry." This registry provides other computers on the Internet the information necessary to send you e-mail or to find your web site. You will also be required to enter a registration contract with the registrar, which sets forth the terms under which your registration is accepted and will be maintained.

Public information provided from Internic and local instance of Internic (the DNS)

Conversion between Name and IP number : Dig / NSlookup

Who that name belongs to : WhoIs or WhoIs

Each DNS server ensures that no two domains under it have the same domain name. Then as a result, no two domain names worldwide are the same.

No one can practically handle the job of mapping domain names to the corresponding IP addresses worldwide.

Domain names keep changing, and there are many new added ones.

DNS is a hierarchically structured, distributed database system.

When an IP address is to be found given a domain name, a library procedure called resolver requests DNS server for the IP address. If found, it is returned to the caller. Otherwise the DNS server calls up a higher level DNS. Higher level DNS may call some other higher or lower level DNS servers.

ICANN is at the root of the Internet

Internet Corporation for Assigned Names and Numbers

ICANN still belongs to the US : Big political issue : should be associated to the UN !

Eg. ICANN gave away the'.com' to the US registrare VeriSign up to 2012: 6$/year   (+7% raise a year) * 35 billion name ...