Another IP Question
 

this is really weird.


i have cable connection and my home is networked between 2 pc's using a router.

when i connect to the net using the router, i get one ip.

if i connect straight using the modem, i get a diff ip (i get the ip's by goin to http://www.whatismyip.com/

can somebody plz explain this to me?

Basically the modem is considered a seperate connection, so it gets its own ip.

think of it as if you have 2 network cards, 1 going to router a and the other going to router b. Router a assigns the card 1 ip A, router b assigns it's card ip B. Now each card needs it's own ip to operate, so your computer has 2 ips, ip A (for network card A), and ip B (for network card B).

This is basically what you are doing (yes, a modem connection will be "seen" as if it was a separate network card (in the above example). This is a bit confusing, but if you need clarification, i'm sure that i can try again, or someone might have an easier way to explain it.

If you were to check your routers external IP you would find it to be the same as the ip if you connected it to your computer. Taht is the IP that the World sees. When you connect your Router to your computer you are essentially setting up a Internal network and therefore it would be a different IP. The IP you see when you plug the network card into the Modem, is the IP that your ISP is assigning you. The IP you see when you connect to your router is the IP your Router is assigning you, and your ISP is assigning your router your old IP.

Also it could be much eaiser then this. Perhaps you are on a dynamic IP service for your ISP, and in witch case your IP would change if you changed the MAC Address (one would be your router the other would be your Network card)

most of the cable modem providers set the IP by mac address of the network card or router. this is why you get two different external addresses.

*waits for him to say "no, i use a pc, not a mac" or something*

why?

doesnt all nic's have a mac address on them?


so, i currently have 3 diff ip addresses? (external ones)

one for pc1, one for pc2, and one for router?

All nics do have a mac

your two pc's ip should be being set by your router or modem, if you are using DHCP or NAT

so you will have 3 ips, two internal , one external.

the internal ones should be 192.168 or 10.0. or 90.0 or such