Simple IP Question

[Reno]

Imagine a scenario where 4 small apartments, all in a row, connect via broadband to the same provider, using 4 different accounts. Four different people with 4 different computers, all online at the same time, and no one being very far distance wise from the other 3.

They all come to my website in the same 20 minute span, where my stats program records IP addresses.

Will each of them have the exact same IP address? or is each one unique?

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[lammert]

There are several scenarios possible:

• If they all share the same router, they will all have the same IP address
• If they all have separate routers but the ISP uses an upstream NAT proxy, they will all have the same IP address, or they will have IP addresses which are close to each other, often within the same Class C block. (i.e. only the last part of the IP addresses differ)
• If they all have separate routers which connect to the Internet without an upstream NAT proxy, they will all have different IP addresses.

Some ISPs like AOL are known for their upstream NAT proxies.

[Reno]

Thanks very much for your detailed answer -- much appreciated. In my scenario the 4 apartments would have different routers, as they are all individuals who would not necessarily know each other.

Just wondering about this, as when I study specific IP's in my stats, I'm wondering if each one is a distinct individual connection, or would multiple people (from the same part of the same block for example) all have the same IP. Your answer clears that up.

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