IP address question

[ddeder]

I have a laptop, netgear wireless router and cable internet access.

If I plug the cable modem into the laptop with an ethernet cable, The IP address of the laptop is 72.135.42.197 and the subnet mask is 255.255.254.0.

If I plug the cable modem into my wireless router and then connect wirelessly, the router says my internet IP address is 65.29.59.3 and the subnet mask is 255.255.255.0.

My laptop is assigned 192.168.100.2 by DHCP.

I understand where the 192.168.100.2 comes from.

I do not understand why my router comes up with 65.29.59.3 when the PC is assigned 72.135.42.197 when plugged in directly. Shouldn't these numbers be the same?

 

[John]

Your cable co. is sending a new IP address when your mac address changes. If you were to clone your pc's mac into the router you should see the same ip. 🙂

 

[ddeder]

Thanks.

 

[RebateMonger]

Originally posted by: John
Your cable co. is sending a new IP address when your mac address changes. If you were to clone your pc's mac into the router you should see the same ip. 🙂

That doesn't seem to explain the change in subnets, however. Those two addresses are on different subnets at your ISP. You'd THINK that, in a given neighborhood, all the addresses would be on the same subnet.

If your ISP provides both static and dynamic IP addresses, and if your laptop is set up to receive a dynamic IP address and your router is set up with a static IP address, then you'd see two different IP addresses, probably on different subnets, as you are seeing now.

I'm not saying it's impossible to get two DHCP-assigned IP addresses at the same residence that come from different subnets, but it seems weird.

 

[Thoreau]

I've had IPs from totally different ranges assigned to me from Cox many times in the past. Not sure how they do their routing, but as long as it works and I *do* get an IP, i'm certainly not complaining.