Does every domain have unique IPs?

Question

I want to know whether every domain adress has a unique IP adress? Furthermore, where these IP\'s are located? and how does this redirection system works? When we try to access

Answer 1

No : each domain does not have its own IP address.

Several domains can be hosted on the same server -- and on the same IP address.
That's the idea behind Apache's VirtualHosts, for example.

And one domain-name can correspond to several distinct IP addresses.

For example, using the dig command on the google.fr domain, you'd get (I only copy-pasted a portion of the output) :

$ dig google.fr

;; ANSWER SECTION:
google.fr.              71      IN      A       74.125.230.81
google.fr.              71      IN      A       74.125.230.82
google.fr.              71      IN      A       74.125.230.83
google.fr.              71      IN      A       74.125.230.84
google.fr.              71      IN      A       74.125.230.80

For more informations, you should probably read the following wikipedia entry : Domain Name System.