Regarding IP address

OK, it is hard to parse your question, so hopefully my answer will cover it.

Reason, and the spec, DEMAND that a given network interface have only ONE address of a given type. Current types are generally:

MAC ADDRESS...This is usually handled by hardware in the background, and cheap imports and laziness make it no longer really unique.

TCP v4... format is xxx.xxx.xxx.xxx
TCP v6... format is separated by colons
GATEWAY This address is used by the client to facilitate access to some services, etc...

You CAN have SEVERAL interfaces though on a given computer. On MY laptop now I have several. They are:

Wireless LAN adapter Wireless Network Connection ... for my main wireless.
Ethernet adapter VMware Network Adapter VMnetx ... to allow a VM instance to communicate via the network.
Tunnel adaptors.... allow a secondary protocol to "TUNNEL" through the TCP/IP one.

Anyway, you get the idea.

Routers and hubs are special since they translate and spread out IP access. So a typical home router converts the often PUBLIC IP from your provider to several often PRIVATE internal IPs. EACH has its own socket going to a separate computer. All computers have only one IP, which is only for THEM, even if 256 devices are hooked up to that one router.

Steve