Originally Posted by iain
>>But i wonder, what is controlling what computer to have which IP adress?
On a private network, the IP addresses can be set by the administrator. They have to be non-routable (eg 10.0.0.20). Also they can be issues by a DCHP server (dynamic host configuration protocol) where permitted IP addresses are issued to clients.
The DHCP system is widely used by internet service providers to assign clients an IP address.
At the next level up, i believe it is the country registar that is responsible for issuing IP blocks to service providers, then ICANN